bulkhead sailboat

Building, restoration, and repair with epoxy

Replacing Damaged Bulkheads

By dan witucki.

Above: With her damaged bulkheads replaced, the Evelyn 32-2 sailboat RUSH is back in action. Several weeks later, the new bulkheads proved they could handle the stress of a heavy knockdown and a major storm during the infamous 2002 Chicago to Mackinac race.

If you race a sailboat long and hard enough, it eventually will reveal its weaknesses, sometimes violently. My friends and I race an Evelyn 32-2 called Rush. Less than a month before the 2002 Mackinaw races, we were competing in the Saginaw Bay Yacht Racing Association, Gravelly Shoals race. Throughout the race, the wind had been building and we were a little overpowered with a full main and 150% headsail. We had completed about 45 miles of the 50-mile race when the starboard chainplate decided it had enough and pulled out of the bulkhead.

The port bulkhead with the chainplate still attached.

Fortunately, Evelyn 32’s are designed with a stainless wire strut running from the chainplate down to near the mast step. This kept the rig from coming down; however, we were definitely done racing for a while.

After limping back to the dock and examining the damage, we decided to completely replace the bulkhead on both sides of the boat. Over the years, the chainplates had been leaking and had delaminated and rotted the plywood bulkheads. Before the accident, the bulkheads looked fine, but it was amazing to see afterward how badly they actually had deteriorated. With the end grain of the plywood bulkhead up against the underside of the deck, the chainplate was leaking directly onto the exposed end grain of the wood. Water damage was inevitable.

The next decision that had to be made was what material to use for the new bulkheads. The original, damaged bulkheads were made of ” marine grade mahogany plywood. However, we weren’t too anxious to use plywood again. It would be quick and easy, but we wanted something more bulletproof than plywood. After talking to Gougeon Technical Advisor, J.R. Watson , we decided to go with an epoxy/fiberglass composite called G-10. We selected ½” G-10 to replace the 5/8″ plywood. Because of G-10’s strength, we could have gone thinner yet. However, that would have made it more difficult to install and have everything else match up.

Removing the old, damaged bulkheads

Although I usually do most of the fiberglass and fairing work on Rush, John DeWyse did most of this job. The first step was to remove the shrouds and fasten them to the toe rail. Then it was time to go below and take the interior apart.

The starboard bulkhead where the chainplate let go was the result of accumulated water damage and heavy loads.

Luckily, Evelyn 32’s aren’t real plush, and this job went fairly quickly. We moved all the sails, equipment, and cushions from the bow and mid-section of the boat to the stern. Then we hung a tarp behind the companionway to keep the dust away from that area of the boat. We placed a large window fan over the front hatch, blowing out. With the companionway open, we had good ventilation. The next step was to carefully peel back the headliner and inner upholstery with a putty knife and tape them back out of the way. To cut the bulkheads free, John used a Roto Zip™ tool. This worked very quickly with minimal dust. He simply went down each side of the bulkhead, cutting the tabbing where the bulkhead met the hull and deck. He had both damaged bulkheads out after about 1½ hours. Then he used a 6″ grinder with a 40-grit disc to remove the old glass tabbing on the hull and underside of the deck. After that, we vacuumed up the dust.

Installing the new bulkheads

Since John was able to get the bulkheads out without damaging them further, they made perfect templates. When the G-10 arrived, we traced the bulkheads onto the new material using a black felt tip marker, modifying them slightly from the original design. We decided to extend the bottom of the bulkhead so that it could be bolted and glued to a floor frame that was below the original bulkhead. To cut the G-10 composite, we used a reciprocating saw with a carbide grit blade used for cutting cast iron and fiberglass.

John used a Roto Zip to cut the tabbing where the bulkhead met the hull and deck. The Roto Zip cut quickly and raised minimal amount of dust.

Cutting was rather slow; this stuff is tough. Taking turns, we were able to cut each bulkhead out in about an hour. The new bulkheads were taken down to the boat and put into place. After we had ground down a couple of high spots, they fit perfectly. Next, I ground and sanded a radius on the long straight edge, since this edge would be exposed to the interior. I finished preparing the bulkheads by using a random dual action sander with 80-grit paper to sand the edges where the tabbing will bond it to the hull and deck.

With the starboard bulkhead removed we were ready to remove the glass tabbing with a disc grinder.

With the bulkheads set into place, we cut strips of 738 Biaxial Fabric (with a mat backing) needed to tab the bulkheads into place. We cut enough to do both sides of the bulkheads with two layers of cloth, then set them aside. With the bulkheads still in place, we drilled three holes through the bottom of each bulkhead and through the floor frame. We used 3/8″ stainless bolts to fasten these together, but drilled 7/16″ holes. Later, when we glued in the bulkhead, we filled these holes with thickened glue, inserted the bolts, and tightened them down. This forms a very strong bond with all of the bolts loaded equally.

We later mounted the chainplates in the same manner. To glue the new bulkheads in place, we made a mixture of WEST SYSTEM® 105/206 epoxy thickened with 406 Filler to a peanut butter consistency. We removed one bulkhead and buttered the edge where it meets the hull and deck with a thick layer of epoxy using a plastic spreader. We also applied epoxy to the side of the frame where the new bulkhead overlapped it and in the three bolt holes in the bulkhead and stringer. We then clamped and bolted the bulkhead into place. John formed a fillet on both sides of the bulkheads where the glass tabbing would be applied, using more thickened epoxy and a plastic spreader with a radius cut on one corner.

After the epoxy had started to set, John wet out the fiberglass cloth with a mixture of 105/206 and applied the strips. The first strip had 60% of the cloth on the bulkhead and the second layer had 60% of the cloth on the hull side of the joint. This staggering of the glass forms a strong joint without the need to cut two different widths of glass. Air bubbles were worked out with a plastic spreader.

The next day, after careful measurement, we drilled the chainplate holes. Then we glued and bolted in the chainplates as previously described. We later caulked around them on deck. Then we cleaned and put the interior back together. We waited three days before installing the shrouds and tuning the rig. Although this bulkhead replacement job had looked rather intimidating, in reality, it was rather straightforward and we completed it in about 20 hours.

The bottom of the bulkhead/hull joint before the old tabbing was removed. We would extend the bottoms of the new bulkheads so they could be bonded to the side of the floor that ran transversely across the bottom of the hull.

Stress Test

Several weeks later, in the Chicago to Mackinac Island race, we tested our repair. During the second day of the race, the wind had been building and we were surfing, hitting 14’s, when we experienced a hard knockdown that laid the mast in the water. Later that evening, a strong storm tore through the fleet dismasting several 80′ boats, pitchpoling a 40′ catamaran and making a number of sail lofts very happy. We had the full main up and were in the process of taking down our chute when the storm hit. We were told it blew 60-70 knots (we had lost our instruments and masthead unit in the earlier knockdown). The boat and her new bulkheads weathered the storm just fine, and the crew’s nerves are nearly back to normal.

We used the old bulkhead as a template to layout the new bulkhead, and then sanded the edges of the new G-10 bulkhead to prepare the surfaces where the new tabbing will be bonded.

Two layers of 738 Biaxial Fabric tabbing were applied to each side of the bulkhead to reinforce the joint between the bulkhead and the hull and deck.

What Are Bulkheads In Ships?

Bulkheads in ships can be defined as the vertical separations on a vessel that run both transversely and longitudinally. Their primary function is to provide structural rigidity for a vessel against forces in both transversal and longitudinal directions and also act as a sub-division for separating the vessel into a number of watertight compartments.

When designing bulkheads, considerations are made on the overall structural integrity with respect to the loads carried by the bulkheads. Mostly transverse bulkheads carry both vertical and transversal loads and provide structural rigidity against torsional forces.

Most of the primary bulkheads used for structural reinforcements are made water-tight so as to prevent water from occupying the entire volume of the vessel during undesired events like flooding.

They also act as containing the fire within compartments.  There are also secondary bulkheads that are used for separating interior spaces such as accommodation spaces which don’t have any structural importance.

The design of bulkheads in ships is followed as per classification society rules and was made very strict after one of the major accidents in the history of cruise vessels , The Titanic. The Titanic sank due to the absence of bulkheads extending vertically to the main deck which led to the overall flooding of the vessel.

Rules have been made so as to ensure further events like the same don’t happen in the future. The class society put forwards a rule where a vessel of a particular length should have a minimum number of bulkheads with primary bulkheads such as collision bulkheads, aft peak bulkheads, and watertight bulkheads.

Different Types Of Bulkheads in Ships

Different bulkheads are provided for different functions and they vary as per the locations. The following are the most common types of bulkheads found in most vessels.

• Collision Bulkhead

It is the forwardmost bulkhead, regardless of the type of vessel. The primary function of this bulkhead is to contain flooding throughout the vessel by acting like a solid wall that is located aft of the bow, such that even if the bow gets damaged during a collision, the bulkhead will prevent the water from flooding into any other compartments.

The structural design of collision bulkheads in ships is also done with this regard and normally a stronger bulkhead design is adopted and positioned in such a way that it is at an optimum location from the bow , not too aft or not too close with respect to the bow.

A classification society also gives specific rules regarding the location of the collision bulkheads relating to the overall length of the vessel and also factors that depend on the geometry of the vessel’s bow design.

• Aft-Peak bulkhead

The aft peak bulkhead is designed to house the stern tubes of a vessel in a contained environment such that it acts like a flood barrier during undesired events. The location of the aft peak bulkheads is determined while keeping in mind that the vessel should not trim excessively by the stern during flooding.

• Watertight bulkheads

The sub-division of any vessel mostly comprises water-tight bulkheads. They are designed in such a way as to contain flooding within a certain localized region of the vessel during flooding, which thereby gives the vessel better reserve buoyancy. Reserve buoyancy is the key in terms of vessel stability for safely returning to port without catastrophic damage.

Watertight bulkheads in ships segregate the machinery spaces, cargo holds, and so on. Machinery spaces, they are also designed to localize fire within the specified spaces such that the fire doesn’t spread throughout the vessel.

How Many Bulkheads Does My Vessel Need?

A minimum number of bulkheads in ships and their functions are determined by the classification society normally based on the length of a vessel. As the length increases more bulkheads are needed so as to not only subdivide the vessel but also provide transversal strength.

For passenger vessels, the classification society makes sure that maximum safety is provided such that no danger to human life happens at the sea. It is necessary that all passenger vessels carrying more than 12 people should adhere to the SOLAS (Safety of Life at Sea) rules.

The rules specify the design and construction of bulkheads so that even if undesired events such as flooding, the water is confined in a specific compartment and the vessel doesn’t lose its stability due to excessive trim and sinkage.

Design and Construction of Bulkheads.

Bulkheads are designed to calculate the global loads acting on them during a vessel’s lifecycle. Naval Architects use computational tools such as FEA (Finite element analysis) to compute the loads acting on the bulkheads and come up with an efficient design solution that gives the builder the details about the material and its geometric properties.

On smaller-sized vessels, bulkheads are usually constructed with a single plate that is welded onto the side and bottom plates. In the case of larger vessels, they usually have two or more sections welded together to form a single unit. Also, the thickness of these units increases with depth such that they are structurally stable during flooding, when the entire compartment gets flooded the lower sections will be subjected to the maximum hydrostatic forces.

In addition, the bulkheads are further stiffened with the help of transversal or vertical stiffeners which normally have flat, angled, or bulb sections.

In most of the cases, we see vertical stiffeners, as transversal stiffeners would need to cover a longer span for vessels with a higher beam, whereas in the case of vertical stiffeners we can keep the overall scantlings of the vessel low, by addition of stringers at the midplane of the bulkheads which can reduce the overall span of the vertical stiffeners.

For efficient load transfer from the top and bottom plating of the bulkheads in ships , it is necessary for the stiffeners to end at the plating in a well-defined manner. At the upper and lower plating of the bulkheads, end brackets are provided at the intersection points which connect the stiffeners to the plating which corresponds to a hinged boundary condition that accounts for an efficient load transfer from the plates to the stiffeners. 

What Are Corrugated Bulkheads?

Corrugated bulkheads in ships are those whose plates are shaped into alternative grooves and ridges, i.e., corrugations and ridges prior to their fabrication which allows the elimination of structural stiffeners on bulkhead plates.

These corrugations can either be vertical or transversal in direction. They are easy to fabricate, as they reduce the number of welded sections, and make installation easier. Also, the corrugations provide ease of repair and maintenance.

On the downside, corrugated bulkheads are made up of plates having a uniform thickness which can increase the overall weight when compared to bulkheads having stiffeners. They are most commonly used in average-sized chemical or product tankers and are positioned as a boundary between each individual cargo tank. They are also treated with special compounds such that the chemical doesn’t corrode the bulkheads easily.

Testing And Safety For Bulkheads

Bulkheads and their boundaries are tested so as to make sure they are watertight. Bulkheads forming tank boundaries are usually tested by pressure testing the tanks. Both forepeak and aft peak bulkheads are tested by filling water till the load water line and ensuring that there are no leakages.

For all other bulkheads, they are normally hose tested for about 200 kn/m2 against the side with stiffeners whereas in the case of corrugated bulkheads any side may be chosen.

In terms of insulation for fire protection, it is made sure that for those bulkheads between the boundaries of machinery spaces the average exposed side temperature that is the walls facing towards the machinery space does not rise above 139 degrees Celsius and the temperature at a single concentrated point should not rise above 225 degree Celsius.

Bulkheads in ships are an essential part of a marine vessel in terms of providing structural integrity, subdivision, and safety for the vessel during undesired events such as flooding.

Bulkheads help in containing the spread of water in localized spaces during flooding such that the overall reserve buoyancy is maintained with which the vessel can reach safely back to port without any catastrophic damages.

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About the author

I worked as an officer in the deck department on various types of vessels, including oil and chemical tankers, LPG carriers, and even reefer and TSHD in the early years. Currently employed as Marine Surveyor carrying cargo, draft, bunker, and warranty survey.

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Understanding Watertight Bulkheads In Ships: Construction and SOLAS Regulations

The safety of a ship in damaged condition is majorly dependent on the strength and integrity of its watertight bulkheads. There are a lot of factors that go into deciding the position of watertight bulkheads in a ship, and designing them structurally.

Watertight bulkheads are vertically designed watertight divisions/walls within the ship’s structure to avoid ingress of water in the compartment if the adjacent compartment is flooded due to damage in ship’s hull.

The position of the bulkheads along the length of the ship is primarily decided by the results of flood-able length calculations during the assessment of damaged stability of the ship . However, once their positions are fixed, there are a lot of factors coming into play, for example: types of watertight bulkheads, their uniqueness based on their position, structural design, etc.

Collision Bulkhead

A collision bulkhead is the forward-most bulkhead in a ship. There are two factors that determine the position of a forward collision bulkhead. The final position of the collision bulkhead is so decided that it takes into consideration both the factors listed below:

Factor 1: Position based on flood-able length calculations.

Factor 2: Position based on the classification society code books . Most of the classification society rules have an allowable range of distance at which the collision bulkhead can be placed from the forward-most point of the ship’s hull. This distance is usually a function of the length of the ship and factors related to the shape of its bow.

Factor 3: Position based on SOLAS rule , which states that the collision bulkhead should be located aft of the forward perpendicular at a distance not less than 5 percent of the ship’s length of the ship or 10 meters (whichever is less). The distance must also not exceed 8 percent of the ship’s length.

However, the position of the collision bulkhead should be such that maximum cargo storage volume is achieved.

The collision bulkhead is a heavily strengthened structure, its main purpose being limiting the damage of a head-on collision to the part of the bow forward to it. To limit the damage to its forward region also means that the collision bulkhead is watertight bulkhead. It is usually vertically stiffened with sections of scantlings higher than those on the surrounding structures. It is also stiffened by triangular stringers of higher scantling, called panting stringers. Panting stringers are usually provided at every 2 meters from the bottom, forward of the collision bulkhead.

Related Reading: 12 Maritime Books All Seafarers Must Have

As per SOLAS rules,

• The collision bulkhead must be watertight upto the bulkhead deck. A bulkhead deck is basically the deck level upto which all the watertight bulkheads are extended.
• For providing access to chain locker room and the forward part of the bulkhead, steps may be provided on the collision bulkhead. However, this must not violate Factor 3.
• There must be no doors, manholes, access hatches, ventilation ducts or any openings on the collision bulkhead below the bulkhead deck. However, the bulkhead can be allowed to have only one piercing below the bulkhead deck for the passage of one pipe to cater to the fluid flow to the forepeak ballast tank. The passage of the pipe must be flanged and must be fitted with a screw-down valve which can be remotely operated from above the bulkhead deck. This valve is usually located forward of the collision bulkhead. However, the classification society certifying the ship may authorise a valve aft of the bulkhead provided it is easily serviceable at any condition, and is not located in the cargo area.
• In case of ships having superstructures at the forward region, the collision bulkhead is not terminated at the bulkhead deck. It must be extended to the deck level next to the weather deck. This would ensure sufficient structural continuity and keep the shear forces within safe limits.
• If the collision bulkhead is extended above the freeboard deck, the number of openings on the bulkhead should be restricted to a minimum in order to ensure sufficient buckling strength. All the openings should be watertight.

Related Reading:

What makes a ship unstable?

Understanding curves of static stability

Construction of Watertight Bulkheads

The primary function of watertight bulkheads is to divide a ship into a number of watertight compartments. Though most watertight bulkheads are transverse in orientation, some ships also have longitudinal watertight bulkheads within a compartment for longitudinal compartmentalisation within a compartment. Other than watertightness, the transverse bulkheads also add to the transverse strength of the ship. We will look into that aspect a little later.

In small ships, a transverse bulkhead may be constructed from a single plate. However, for larger ships, the plating of a transverse bulkhead usually consists of a series of horizontal strakes welded together. But what’s interesting here is that, the thickness of these strakes increase with depth, in order to strengthen the bulkhead against the maximum hydrostatic pressure in case the compartment is fully flooded. So prior to erection, two dimensional strakes are first cut out from plates of different thicknesses.

The bulkhead plate itself is not resistant enough against large scale transverse forces like shear forces. So they are stiffened, either vertically or horizontally. But we usually go for the vertical stiffening instead of the horizontal. Why? Because horizontal stiffening in ships with high beam would require stiffeners of long span, which would also increase the scantling and weight of the stiffener, affecting usable cargo volume. However, with vertical stiffening, the span (and hence, the scantling) of the stiffener can be kept low by introducing a stringer at mid-depth (a stringer acts as a fixed end, therefore reducing the span).

The sections used for stiffening the bulkheads are usually flat bars, angles or bulb bars, depending upon the required section modulus. An important aspect of the design of bulkhead stiffeners is meeting the end conditions. In order to meet the boundary conditions so that the stiffeners respond as per the theoretical calculations, their end supports must be designed accordingly. At the upper end, they are attached to the underside of the deck plating with brackets, providing a hinged boundary condition. To achieve fixed ends, they are welded directly to the deck plate and the stringer.

Most modern day ships use an advanced technology to achieve the required strength of bulkhead plates. They use corrugated bulkheads instead of stiffened ones. The corrugations are in the vertical direction, except when the breadth of the bulkhead is significantly low. However, there is one trade-off that needs to be made here. Since the corrugations are provided on the bulkhead plate right in the early fabrication stage, corrugated bulkheads are made of plates having uniform thickness (which is, the thickness equal to the lower most strake in case of a conventional bulkhead). This increases the weight of the bulkhead when compared to a conventionally stiffened bulkhead. In spite of this, usage of corrugated bulkheads come handy due to ease in fabrication and reduction of welded joints on the bulkhead.

The above figure shows the elevation of a corrugated bulkhead from the side. In case of bulk carriers , in order to prevent accumulation of cargo at the base of the corrugations, the lower end of the bulkheads are provided with angular plates called shredder plates, which help in shredding the dry cargo to the tank top. The bulkhead is connected to the tank top by a bulkhead stool, which is fillet welded to the tank top plate. The two forward and aft ends of the stool is to be in line with the transverse plate floors. This ensures proper stress flow from the bulkhead to the plate floors.

As shown above, the corners, where the bulkhead plate is welded to the side shell and the deck plate, or the tank top, separate corner plates are welded to complete the joint after welding the remaining bulkhead plate to the hull. These corner plates are provided for the following reasons:

• Fitting the entire bulkhead panel (with the corners) would be difficult from a production point of view since every structure is first fabricated with certain amount of green material. Before final installation, the green material is removed, and structures as huge as bulkheads require repeated checks for proper dimensional adherence. Eliminating the corners from this stage would reduce the complexity of maintaining dimensional precision at the corners.
• Stress concentration occurs at corners due to discontinuity of structure. In order to prevent this, corner plates are provided with additional thickness than the adjacent bulkhead plating.

Pressure Testing of Watertight Bulkheads

After installation of the bulkheads, they are to be tested for their integrity and water tightness. Since it is not feasible to fill all the cargo holds or compartments with water for this purpose, the test is done by a pressure hose. In this process, the bulkhead is subjected to a prerequisite water pressure from a hose for a fixed period of time, after which, the structural integrity of the bulkhead is inspected (checks are done for buckling and other deformations). Leak tests can also be done by pressurising the air in a compartment and checking for leakage of air to the other compartment.

Watertight Doors

Intactness is the primary purpose to be maintained by a watertight bulkhead. But in most ships, there are situations unavoidable where access from one compartment to another is a necessity. For example, an under-deck access from one cargo hold to another or from one compartment to another in case of passenger ships. In most ships, access to the shaft tunnel is necessary especially to monitor shaft oil temperatures or for repairs in the region. This purpose is solved by the use of watertight doors.

The bulkhead panel is usually cut out in a rectangular shape accommodating a watertight door . However, special incorporations are made in the structural design of the region around the door opening:

• The dimensions of the opening are kept to the minimum.
• An opening results in a major structural discontinuity, resulting in stress concentration around the opening. To maintain stress levels below safety limits, the opening is strengthened by doubler plates to increase the thickness of the bulkhead plate around the opening.
• If a vertical bulkhead stiffener comes in the way of the opening, it is terminated at the upper and lower edges of the opening. However, designers might choose to increase the stiffener spacing to avoid this. In that case, the scantling of the stiffeners adjacent to the opening are increased from the remaining stiffeners.

Watertight doors are usually hydraulically or electrically operated, and are either horizontally or vertically sliding. The reason why swinging doors are not provided in watertight bulkheads is because it would be impossible to close a swinging door in case of flooding. It must be easily operable even when the ship has listed to 15 degrees to either side, and the control system should be so designed that the door can be operated from the vicinity as well as remotely, i.e. from a position above the bulkhead deck. In all ships, visual indicators are provided at the remote control location to denote whether the door is open or closed.

Watertight doors are also subjected to pressure tests after installation to check for their structural integrity at design hydrostatic pressure in case of complete flooding up to the bulkhead deck.

SOLAS Rules Pertaining to Watertight Bulkheads

One of the most important regulations to be complied with during the design of watertight bulkheads and doors are that of SOLAS, and some important ones are discussed below:

• The number of openings for pipes and access should be kept to minimum in order to retain the strength of the bulkhead. In case such openings are provided, proper reinforcement must be provided so as to prevent stress concentration, and retain water tightness of the structure. Proper flanging must be incorporated in openings for pipelines and cables.
• Not more than one watertight door is allowed per watertight bulkhead. However, in case of ships having twin shafts, there may be two watertight doors, each providing access to the two shaft tunnels on either side. The mechanical gears required for manual operation of these doors must be located outside the machinery spaces.
• The time required to close or open any watertight door when triggered from the control room or navigation deck should not exceed 60 seconds when the ship is in upright condition.
• The transverse location of the watertight doors should be such that they must be easily operable even when the damage to the ship is within one fifth of the ship’s breadth from its side shell.
• Every watertight door should be equipped with an audible alarm distinct from all other alarms in the area. In case the door is being operated remotely, the alarm should start sounding at least 5 seconds before the door begins to slide either way, and must continue till it has completely opened or closed. However, if operated in situ, the alarm must sound only when the door is sliding. In case of passenger ships, the audible alarm must be accompanied by a visual alarm.
• All watertight doors that are accessible during voyage must be locked via an authorised unlocking system.
• Access doors and hatches on watertight bulkheads must remain closed when the ship is at sea. Visual indicators must be provided for every access hatch to indicate their status at the location and the navigation bridge.

Fire Class of Bulkheads

In order to prevent the propagation of fire from one compartment to another, all watertight bulkheads are also provided with fire-resistant paneling. However, depending on the extent to which bulkheads can retain the fire and smoke to the affected side, they are classified into three categories:

Class-A Panel: All watertight bulkheads are Class-A type. Bulkheads of Class A must be constructed of steel or equivalent material and should pass the standard fire test, preventing the passage of fire or smoke to the unaffected side for at least one hour. With Class A bulkheads in use, the average temperature on the unaffected side must not exceed 120 degree Celsius. Added to that, there are three categories of Class A panels depending on the time up to which the temperature at any point on the bulkhead must not rise above 160 degree Celsius:

A-60 Panel: 60 minutes.

A-30 Panel: 30 minutes.

A-15 Panel: 15 minutes.

A-0 panel: 0 minutes.

Class-B Panel: Bulkheads of Class B are constructed of materials that are approved by SOLAS and classification societies as incombustible materials. And should pass the standard fire test, preventing the passage of fire or smoke to the unaffected side for at least thirty minutes. With Class B bulkheads in use, the average temperature on the unaffected side must not exceed 120 degree Celsius. There are two types of Class B panels depending on the time up to which the temperature at any point on the bulkhead must not rise above 206 degree Celsius:

B-15 Panel: 15 minutes.

B-0 panel: 0 minutes.

Class-C Panel: Class C bulkheads and decks are constructed of materials that are approved by SOLAS and classification societies as incombustible, but they are not required to meet any requirements related to rise in temperature or passage of smoke and flame to the unaffected side.

Class A and B panels are used adjacent to most of the enclosed spaces within the ship, for example: cargo holds, control stations, stairways, lifeboat embarkation stations, galleys, machinery spaces, tanks, public spaces and accommodation areas. Class C panels are mostly used in open decks and promenades, where requirement of fire safety is minimum. They can also be used between two similar spaces if they are not separated by a watertight bulkhead, in which case a Class A panel is mandatory.

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About Author

Soumya is pursuing Naval Architecture and Ocean Engineering at IMU, Visakhapatnam, India. Passionate about marine design, he believes in the importance of sharing maritime technical knowhow among industry personnel and students. He is also the Co-Founder and Editor-in-Chief of Learn Ship Design- A Student Initiative.

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BE THE FIRST TO COMMENT

Very informative article. thanks, Peter

Nice diagram with prompt informations

its thus illustrative

Very informative article, but I didnt find that info anywhere in the book I read. So can I get book references for corrugated bulkhead?

The class A and B bulkhead should have a temperature rise of 140 degree celsius and not 120 degree celsius and at a joint or place for class A bulkhead the maximum temperature rise is 180 degree celsius and for class B Bulkhead is 225 degree celsius.

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Sheathing Bulkheads, Part II: Fit, Glue and Finish

Last month, we showed you how you could turn a big, expensive pile of lumber into a smaller pile of bulkhead sheathing and a large pile of sawdust. This month, we’ll show you how to transform that pile of sheathing into beautiful new bulkheads for your boat. Like making the sheathing stock in the first place, installing it is a tedious operation, full of opportunities to make mistakes.

Undoubtedly, some of your pieces of sheathing will have flaws in them-poor grain, poor color, or knots. As much as possible, you should work around these flaws. In new construction, lay out on the unsheathed bulkhead the locations of furniture, cabinets, hardware, or anything else that will cover up any part of the finished bulkhead. With a little planning, you can hide most of the material flaws in location that won’t show when the boat is finished, such as inside lockers, or settee cushions. Unfortunately, you don’t always have that option in a retrofit. That’s one reason for making extra sheathing stock: the inevitable, badly flawed pieces can go unused.

Surface Preparation

Prepare the plywood bulkhead surface for sheathing by power sanding with coarse (60 grit) sandpaper. If the bulkhead is teak plywood, follow this up with an alcohol wipe down to remove surface oils just before gluing down the sheathing.

The tongue part of your sheathing stock has two purposes: to keep the joint between pieces of sheathing from oozing glue, and to assist in positioning and fastening the stock to the bulkhead. The bulkhead sheathing is attached using a combination of mechanical fasteners and adhesive. Epoxy resin, thickened slightly with a material similar in color to the sheathing (such as fine sawdust from making the stock, or a commercial thickener such as WEST System Tan Filleting Blend) provides the primary holding power.

Staples are used as mechanical fasteners and to hold the sheathing in position while the glue sets, but add little to the structural integrity of the installation. We recommend using an Arrow T-50 tacker with 3/8” monel staples. Do not use ordinary steel staples, and be sure to keep your monel staples clearly separated from any steel ones you have, since it is difficult to tell monel from steel without using a magnet.

You should not use screws to fasten the sheathing, except in areas where they are required to get the sheathing to lie down flat. Even carefully matched bungs in screw holes will detract slightly from the appearance of the bulkhead.

The first piece of sheathing installed is the most critical. It must be absolutely plumb, since the sheathing consists of a series of vertical lines which will look ridiculous if they don’t line up with the other verticles on the boat, such as door edges.

Begin next to a doorway to another true vertical, if possible. This allows you to clamp the first piece into position before gluing, so you can carefully line it up. It is best to overlap the doorway slightly with the first piece, since a joint in the sheathing which lines up with the edge of the doorway will look odd. You can trim off the overlap with a saber saw after the doorway is sheathed.

The tongue edge of each piece of stock is the working edge-the edge against which the next piece will be fitted. If you try to do it the other way around, you won’t be able to staple each piece into position.

Cabin overheads are almost always cambered in section to avoid a boxy look.

This slightly complicates fitting the sheathing tightly overhead. An adjustable bevel gauge can be used to take off the angle between the vertical simple thin cardboard template the width of a piece of sheathing, trial fitting to the top of the cabin using a mat knife and a straight edge. Cardboard templates are also useful when it’s necessary to fit around permanent joiner-work. It’s better to make cutting mistakes on cardboard than expensive wood.

Fitting at the bottom of each piece is the same as fitting at the top. Once again, patterns are helpful. If you’re sheathing a new bulkhead, you may have to relieve the back of each piece of sheathing to fit over the tabbing which holds the bulkhead to the hull. This can be done with a plane, chisel, or belt sander. In some cases the tabbing may be so thick that you can’t cut away enough material on the back to make the sheathing lie perfectly flat. You can get away with having it sprung out slightly, since the edges of bulkheads are usually covered with trim, or are hidden inside other furniture.

The top and bottom bevels are cut with a band saw, saber saw, or coping saw.

When you’re finished with the position of the first piece of sheathing, clamp it firmly in place on the bulkhead along the working edge of the sheathing as an alignment reference. For the second piece in the same fashion as the first, once again using clamps to hold it in position after fitting. From here on out, you won’t be able to directly clamp pieces in position. Instead, clamp a batten to the bulkhead long enough to reach over the piece of sheathing currently being fitted. A thin wedge under the batten will apply enough pressure to the sheathing to keep it from sliding out of place as you work.

We have found it best to install no more than four pieces of sheathing – about a foot of bulkhead width – in any one gluing. More than that becomes awkward to glue, clamp, and staple in place. It’s better to do the bulkhead right, a little at a time, than try to save time by doing it all at once.

You can fine tune the fit of sheathing at the overhead and bottom using a sanding block wrapped with coarse sand paper as a rasp. This is less likely to cause splinters than trying to use a tool such as a block plane or a Surform, and allows subtle shaping of the top to conform with the curve of the cabinet top.

After the last piece of sheathing for the first gluing is fitted, strike another pencil line on the bulkhead along the working edge of this piece. This will indicate the edge of the section of bulkhead to be painted with adhesive for the first gluing. Number the pieces before removing them from the bulkhead, either writing the numbers on masking tape stuck to the surface or by lightly penciling numbers on each face.

You’re now ready for the big test.

Since mixed epoxy resin has a short pot life, get everything ready before mixing up the glue. Lay the pieces of sheathing on a table covered with polyethylene sheeting, to which dripped resin will not stick.

Use either a foam brush or foam roller to coat both the back of each piece of sheathing and the face of the bulkhead. Coat both with unfilled resin first, then mix thickener into the resin and brush another coat onto the back of each piece of sheathing. The thickened resin should be the consistency of honey, so it can fill any gaps between the sheathing and the bulkhead surface. It should be brushed out fairly evenly, leveling with a wide putty knife if necessary.

Take your time to position the first piece of sheathing, being careful to line it up with the line you drew on the bulkhead as a reference mark. Use a couple of C-clamps to hold the piece of sheathing in position. Be careful, since the low friction resin-coated surfaces will want to slide around as you tighten the clamps. Use thin pieces of clean scrap wood under the clamps to keep from damaging the surface of the sheathing.

When the first piece of sheathing is clamped into position, staple the tongue to the bulkhead, using firm pressure on the tacker to driver the staples in as far as possible. The staples should be placed about a foot apart, as far in from the edge of the tongue as possible, with the long axis of the staple parallel to the edge of the tongue.

Even using a lot of pressure on the tacker, the staples will probably not drive all the way into the bulkhead. Use a ¼” diameter pin punch and hammer to set them flush with the surface of the tongue.

Aligning the next piece is easier, since it is simply butted up against the edge of the first, then stapled down. After stapling the edge of the second piece, you’ll notice that its groove edge – which is not stapled down – has probably lifted slightly, and is not lying down flush. This edge, and the corresponding edge in the next pieces, will be wedged down after all the pieces in a single gluing are stapled in place on the bulkhead. Now you see why it’s best to fit only a few pieces of sheathing at a time.

Attach the next piece or pieces in the same manner as the second.

You now must face the problem of making the sheathing lie down flat. This is accomplished using a number of battens about ¾” square, which can be made from any type of clean scrap. These are clamped to the edge of the bulkhead at the doorway, allowing them to overlap the last piece of sheathing on the bulkhead by a couple of inches. Drive a screw through the batten into the bulkhead just past the last piece of sheathing. The screw hole in the bulkhead will be covered by the first sheathing strake of the next gluing.

While the batten will do a pretty good job of flattening out the sheathing, you will probably have to use thin wedges or shims under the batten to really hold things down flat. By pressing on the face of the sheathing with your fingers, you be able to feel any sections that are not lying down flat on the bulkhead below. Add more battens and wedges as necessary to hold things down firmly.

Now clean up the mess of glue that has probably squeezed out between some pieces of sheathing and at the top and at the bottom of each piece. A rag dipped in stove alcohol or shellac thinner will remove gobs of epoxy from your sheathing. Use a putty knife to clean up glue that has squeezed past the edge of the last piece of sheathing, to leave the bulkhead clean for fitting and gluing the next the next pieces.

Cleanup is critical. The more effort you put into removing glue while it is still wet, the less work you will have when finishing the surface after the bulkhead is completed.

Always wears latex exam gloves when working with epoxies. A box of 100 costs about $1.5, and it’s the best $15 you’ll ever spend. Epoxy sensitization is permanent, and miserable. Wash any epoxy which gets on your skin off with soap and hot water before it sets up. Don’t use solvents to clean your skin unless absolutely necessary, and then use alcohol, not anything more powerful. Even alcohol has a serious drying effect on your skin.

Carrying On

Successive fittings and gluings generally get easier, although your hold-down battens must get longer and longer as you go.

A few screws through the sheathing itself will be inevitable, as it will undoubtedly be impossible to wedge some pieces completely flat, particularly at the bottom edges and at the extreme edges and at the extreme outboard edge of the bulkhead. Use as few fastenings as possible, and make them fairly large-diameter panhead stainless steel self tappers driven only flush with the surface. After the glue kicks, the fastenings can be removed and the screw holes counterbored and bunged with plugs cut from the same material as the sheathing. Do not use readymade plugs of what is nominally the same material as your sheathing, since the readymade plugs may b different in color from your own stock.

Work from roughly the centerline of the bulkhead all the way to one side, then work from the center to the other side. You will have to reverse the direction the tongue of the sheathing points when you begin working from the center toward the opposite side, since the tongue would otherwise be hidden. Do this by first gluing a thin “tongue” under the grooved edge of the first piece of sheathing you installed. You’re now ready to start gluing in the other direction.

When you’ve finished installing all the sheathing, your bulkhead will look pretty sorry. It will probably have edges which don’t lie flat, gobs of glue here and there, and torn out surface grain. The effort you will put into finishing turns this rough bulkhead into a thing of beauty.

Begin by machine sanding with coarse paper, gradually working from 50-60 grit down to about 100 grit. Use an orbital sander such as the Makita B04510 or the Porter Cable 330 Block Sander. You can use a block plane to cut down any badly raised edges which weren’t completely down. Don’t worry about them coming loose. Some voids behind the sheathing are inevitable, but they won’t affect anything.

After machine sanding, you must finish sand by hand, using a flexible rubber sanding block of the type used in auto body work, or a homemade block of cork or neoprene. Go back to 80 grit paper, sanding with the grain. Sand out any machine sander swirls on the sander swirls on the surface with 80 grit paper before moving on to 100, then 120 grit, but highly-figured wood must be further sanded with 150 and 180 grit to remove fine scratches.

We prefer a satin finish on interior woodwork. It hides flaws better than gloss varnish, an looks more like a traditional hand rubbed finish. If you’re a real masochist, varnish with gloss varnish until the grain of the wood is completely filled. Then rub down the surface with powdered pumice on a cloth dampened water or furniture oil. You’ll eventually get a beautiful surface unmatched in appearance, but at the cost of untold hours of labor. We’d suggest you try a hand-rubbed finish on something small, like a magazine rack, before committing yourself to doing something as large as a bulkhead this way.

For most of us, a satin interior varnish is more than reasonable substitute. Use at least five costs to fill the grain. Sand between each coat with 180 grit paper, using a tack rag to clean the surface just before applying the next coat of varnish.

Odds and Ends

In new construction, the edges of bulkheads are covered with a margin piece to hide any fitting errors or rough edges. The margin pieces should be of either the same wood as the bulkhead, or of a contrasting wood. The margin pieces should be fairly thin, and must be carefully fitted to the side of the hull. If ceiling is to be installed, margin pieces may be unnecessary, as the cleats for the ceiling will probably hide rough edges.

In retrofits, either reuse the original margin pieces or make new ones of the same material as your new bulkhead, using the old pieces as patterns. The margin pieces should merely be screwed on, either counterboring and bunging flathead screws, or countersinking oval head screws.

Sheathing bulkheads is not a beginner’s project. But with careful planning and cautious execution, it can give your boat an interior unmatched by the stick, run of the mill plywood bulkhead. And it will give you a great deal of pride in your boat.

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FIBERGLASS BOATBUILDING: Internal Hull Structures

We’ve already discussed how a fiberglass laminate is created: what fabrics and resins are used, molds , the problem of blisters , and how cores can be used to make a laminate both stronger and lighter. Now we’ll consider how a simple fiberglass boat hull can be reinforced and strengthened by the structural elements within it. This is necessary, because in fact the molded glass hull of any boat much larger than a dinghy is not normally rigid enough to withstand much abuse. Without internal structures to help stiffen it, a large hull’s laminate would otherwise have to be unreasonably thick and heavy.

The most basic sort of structural reinforcements are called floors and stringers. Floors are transverse sills in the bottom of a hull on which cabin soles are traditionally installed. Besides stiffening the bottom of the hull, floors provide critical support to the root of a sailboat’s keel where it meets the hull. Stringers, meanwhile, are lateral fore-and-aft beams that are installed along the bottom of a hull. Instead of traditional floors and stringers many modern shallow-bilged boats have a unitary grid, sometimes called an “egg crate,” which consists of structural beams running both laterally and transversely across the bottom of the hull.

Bulkheads, partitions, and other structural components of a boat’s interior accommodations and furniture also play an important role in stiffening a hull. Bulkheads are particularly critical, as they can simultaneously provide support to the deck overhead, the bilges below, and the sides of the hull as well.

A primary concern with internal structural components is how they are attached to the hull. On some modern vacuum-bagged or resin-infused boats an egg-crate grid is molded into the bilge as part of the primary hull layup, which is an excellent practice. The traditional procedure, however, is to bond, or tab, internal components in place with strips of fiberglass tape after the hull has been molded. These secondary adhesive bonds are weaker than primary chemical bonds. To create a superior secondary bond the surfaces involved must be properly prepared. In many cases the component being tabbed to the hull is made of wood (often it is plywood), in which case the wood grain must be sealed beforehand or it will suck resin out of the tabbed joint when the fiberglass tape is laid down and wet out. Surfaces on both the structural part and the hull itself should be scratched with sandpaper or a grinding disk to give the resin texture to bite onto; they should also be wiped down with solvent before any glass or resin is applied.

The area of the bonded surfaces must also be large enough to absorb loads on the joint. The rule of thumb is there should be at least a 2-inch margin of tabbing either side of any joint, though a minimum of 3 inches is better, particularly on bulkhead joints. Discrete parts such as grids, floors, and stringers located in the bilges of a boat should be completely glassed over so they don’t absorb any oil or water. Limber holes should also be cut through structures in the bilge so water can flow freely and easily to the lowest point in the hull, where a bilge pump can evacuate it. It may also be necessary to cut access holes through these parts to accommodate wiring or plumbing. The interior surfaces of all such holes must be carefully sealed so they don’t absorb any water or oil passing through them.

Particular care should be taken with any bonded joint that forms a sharp right angle. The danger here, especially with parts like bulkheads or lateral partitions that transfer loads all the way from the deck to the hull, is that so called “hard spots” will be created. These are areas where abruptly imposed structural support within a hull amplifies the total amount of stress created when the area is subject to load. Even where hard spots are created by isolated minor structures such as interior cabinetry, significant stress can result if there is an abrupt impact or collision in the area. The best analogy is that of a stick broken over a knee. The narrow fulcrum of the knee focuses stress in a single area and greatly decreases the load required to break the stick. Bend that same stick over a wider surface–a barrel, say–and there is much less stress. A greater load can be imposed without the stick breaking.

To avoid hard spots it is best if any perpendicular structure bonded to a hull does not actually meet it. Instead, there should be a small gap filled with a softer material like foam, balsa wood, or putty. The joint should also be nicely radiused with a wide fillet. This serves both to reduce stress in the area and to strengthen the bond generally, as the transition from one bonded surface to the other is more gradual. The wider the radiused angle, the stronger the bond will be and the less stress it will experience.

Hull liners

Properly installing an interior hull structure can be very labor intensive. Any economy of scale realized by popping multiple bare hulls from the same mold can be quickly negated by the attention to detail required to properly finish a hull’s interior. This is probably the one phase of boat construction where builders have tried hardest to streamline their procedures. Their key weapon is the molded hull liner, which is simply another large fiberglass part incorporating elements of a boat’s interior that is inserted into a hull.

The larger the part, the bigger the savings in terms of work and effort. A truly comprehensive one-piece hull liner can include not only a structural bilge grid, but also all major furniture components from the bow to the stern. Bulkheads and partitions in these cases are not bonded directly to the hull, but are fitted and glued into pre-molded slots in the hull liner and overhead deck liner or, alternatively, are bolted to special flanges in the liner.

A liner can’t provide much structural support unless it is firmly bonded to its hull in as many places as possible. The usual practice is to lay down beds of adhesive putty (adhesive “splodges”) or thickened resin in appropriate spots, then set the liner down on top of these. This relatively light bond should then be improved by tabbing the liner to the hull with glass tape anywhere there is access to contact points between the two parts. Such access, however, is always limited, and work spaces are often cramped and awkwardly situated.

In the end, it is never possible to create as strong a structure as is formed when all individual components are bonded piece by piece directly to the hull. If the hull is unduly stressed, the liner may break free in some areas. I have heard more than one tale of mass-produced boats failing like this in strong weather. Such damage can be difficult to detect and is always difficult to repair. It may involve cutting away and then rebuilding large portions of the liner in situ, which may prompt an underwriter to declare the boat a total loss.

The best practice is to create the hull liner in small sections and install the parts separately. Ideally, support for the bottom of the hull, usually a grid of some kind, is laid in first. One-piece grid pans are often used, but it is best if the grid is built up in place with each part bonded directly to the hull. Bulkheads and hopefully partitions should also be bonded directly to the hull. Separate interior liner sections can then be laid in place around the bulkheads and on top of the grid. It is easier to create strong bonds between the hull and these smaller, more discrete parts; the bulkheads and bilge structure will also both offer more support to the hull than would otherwise be the case.

Another disadvantage to a hull liner, no matter how it is installed, is that it limits or precludes access to the hull once it is in place. This makes it hard or impossible to repair damage to the hull from within the boat without first cutting away the liner. If the hull is breached while underway, a liner makes it harder to both find and staunch any leak, which is why some cautious cruisers always carry a heavy tool such as an ax or crowbar for quickly tearing away a liner in an emergency.

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Thank you very much, lovely bit of info, I have just bought 23′ Clovic Watson (with no GRP or boating experience) and need to put a floor in the shower/ toilet room. I had a feeling there would be issues with bonding to the hull …onwards … more importantly … must look at engine mountings before engine arrives, thanks again, S xxx

I’m preparing a Reliance 44 for offshore sailing, and part of that included replacing the cabin sole. Once I got a good look at the “grid” holding the current sole I became concerned. Now reading this article I realize that my concern is well placed. The “grid” has been so chopped up and modified over the years that it’s practically non-existent. By the time I’m done with this boat I will have practically built it from scratch!

Very good article.

With less than 2 months sailing experience, I built a 50 foot 23 ton cutter yawl. Just my bride to be and myself. After almost solid daily sailing and cruising for over 42 year the Daedalus is still going strong, never had a blister. As an introduction here’s a six minute aerial video of my Daedalus https://www.youtube.com/watch?v=i07qL_N22_c I launched her August 23, 1977 in Santa Barbara California. I have hand built many things, self studied architecture , became a licensed architect also a US Merchant Marine Master with a passenger sailing endorsement. I have designed and built several boats restored boats, exotic cars all on hand to mouth finances designed and built a bridge The following are portions of my daily log; . In 1974 I had very little sailing experience. I designed; hand built a 50 foot sail boat the Daedalus. The following are excerpts of chapter 11 then later further chapters 12 through 16 if y’all are a bit interested. Thank you Capt. Fred.

Little did I expect to find a partial plywood mold disintegrating in a back yard? The bow and aft end were mostly missing. That old useless mold got my juices going and I could see thru all that mess a very beautiful potential for a hull. The basic shape for this sailboat hull was there and with a lot of bracing and bending, I figured I could do something with it . At that time in history people were building thousands of boats up and down the entire West Coast from Canada to San Diego. I found a build it yourself boat yard on Gutierrez Street in Santa Barbara and rented a little corner of the yard.

About 8 other boats were under construction. Some were under construction for as long as 10 to 15 years, Also, transferring ownership that many times. One fellow boat builder, an Engineer, who said he went through two wives and families already while building his boat, really scoffed at me when I said I would be done in about three years. He asked if I was going to buy a boat kit, which were available in different stages of construction. “No from scratch”, I answered. When he saw the old mold, he raised one eyebrow. His sympathy for me was obvious. At the yard we all became friends and trusted and watched out for each others stuff.

Thousands of boats were under construction on the West Coast and old wooden boats were being demolished by the hundreds of thousands worldwide. Beautiful bronze parts were available. Fiber glass materials were relatively inexpensive and distressed sales were all over the place.

I heard that 10,000 ferro cement boats were built on the West Coast. Sadly, presently there are only a few of them left. The steel mesh armature and sea water make a nice battery that just ate them up. My engineer friend in my boat yard was building out of cement, and he launched at the same time as I launched the DAEDALUS. His 60 foot Ferro cement settled in at about 12 inches above the waterline, to just below the portholes. That is what mindset is all about! However, he just raised the waterline and kept the port holes sealed.

The miracle I experienced building the DAEDALUS was mystifying to say the least. When I needed something, whatever it was, resin, a bronze fitting, the mast, whatever it was. It just seemed to materialize. I found it shortly somewhere. It is almost like something was watching over me and always has. In adventures yet to come, at sea especially, you’ll see what I mean about being watched over. I’m not superstitious or religious, I’m just sayin…

The mold was restored and I fashioned a bow and stern section as I saw fit. I painted the mold with a can of light colored paint, I found lying around. Then I heavy waxed the mold. BTW, I built scaffolding that went all around the inside of the mold without touching it, out of some used 2X10 lumber I found. Now I could reach it all and store supplies and cans and buckets of resin around. I did make a few mistakes, but a major one was not to take a pictorial record of the whole procedure. Big mistake! I did build a kind of shed over, with very valuable used sails I had salvaged. I did not know how valuable they were. https://flic.kr/p/uvzS11

A beautiful old 1930’s 50 foot sloop named the “LAST STRAW”, designed by the most famous yacht builder, Herreshoff,

https://www.surveymonkey.com/s/2JS8GSZsank . It had just left Santa Barbara heading north, to be refitted in San Francisco; she hit the rocks at dangerous Point Conception and was destroyed. Somebody dove and cut off the enormous lead keel, she floated on to the beach. Some farmer said it was his beach and he chained sawed that beautiful yacht into pieces, right through another skylight and some other precious parts.

Frantically I was in the fray trying to save what I could from the LAST STRAW. For $1,000 I saved almost all the major bronze, including all the winches, cleats, sails, beautiful famous Herreshoff teak and copper hatches and thousands of other parts, anchors lines, turnbuckles etc., etc. I was stoked; the antique stainless gimbaled 4 burner propane stove alone was worth almost a $1000. The DAEDALUS was becoming a reality.

There was a furniture factory on on side of the boat yard. Up on the 2nd floor there was one lonely 3 foot wide aluminum sliding window. Out of curiosity I got my ladder and looked in. It was right next to the DAEDALUS. It was a pine paneled room with a sink, refrig, double bed, carpet floor. Hey, what else do we need? Ok, a toilet, which was in the factory. Wow! I spoke to the amiable owner and he rented the room to us and we became kind of his night watchmen and friends. He had just kicked out a girl friend he had secreted in that room. What luck we loved it and moved a ladder to the window and that was our front door to our cozy home for a couple of years. It was great. Friends and relatives visited us there from all over the Country. We ate lots of tortillas and drank lots of rum in that boat yard.

I have several more chapters, but at this point, I’m 87 years old I use a walker and My body can’t keep up much any more. I fin it difficult to sail so I designed an old man’s boat not too tippy something that will allow me to enjoy the wind and the water : https://www.flickr.com/gp/77284431@N02/ih2Lnd

What a life!

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Bulkhead Strengthening

• Thread starter petecasey
• Start date Aug 4, 2024
• Forums for All Owners
• Ask All Sailors

Hey All, I have a 1972 Islander 36, and they’re known to have issues with the bulkhead tabbing. I’m thinking that the bulkheads that hold in the chainplates are too weak and I’d like to strengthen them by adding another layer of wood, then reattaching the chainplates. I’ve seen plenty of discussions on replacing the bulkheads, but no real luck adding thickness to them. One of the bulkheads tabbing has let go, but the other one it is intact and fine. I like working with my hands but wood and fiberglass aren’t my strong suit. To do this can I simply use epoxy and some bolts to attach another piece of wood (likely epoxied or encased in glass)? I’ll tab the new face into the hull and prep that area real well, but I am hoping to get away with just a quick sand instead of getting all the old paint off.  

Attachments

Get a copy of the Gougeon Brothers on Boat Construction: Gougeon Brothers On Boat Construction Book | WEST SYSTEM Epoxy . West Systems makes it available online for free, or you can buy hard copies online. That will get you pointed in the right direction. Adding a layer of plywood to your bulkhead is not as easy as it first sounds. Getting the wood shaped so that it fits properly along the top, bottom, and side is not simple. Getting one piece of wood that large into position may not be possible -- you may have to build it in several sections. This is why using epoxy is an excellent idea. If you epoxy the new bulkhead to a painted surface the epoxy will stick to the paint, and it will be the paint that is holding the bulkhead together. That is probably not what you want. Remove the paint from whatever you are gluing together with epoxy. After the bulkhead has been "bulked up" you will need to tab it to the hull. Again, any paint needs to be removed to achieve a solid connection. Hopefully you will not have to actually remove the chainplates, but simply take out the bolts holding them in the bulkhead and put in longer ones to accommodate the thicker bulkhead. Good luck!  

Timm R Oday25

As someone who has replaced their bulkheads ,here are my thoughts . Our chainplates had elongated the holes that the bolts for the chainplates went through . There wasn't any rot ,even after 40 years I thought I would go from 1/2" to 3/4" when doing the replacement . I spent some good coin , carefully traced the pattern from the original and spent several weeks varnishing and prepping the replacement . When it came time to slip the new and improved version , It wouldn't fit in the channel ...Grrr ..bad words were mumbled . I started over with the original thickness and made darn sure all the ends and the holes were liberally treated to epoxy to prevent future water ingress . I'd say I'm good for another 40 years. Your bulkheads don't look all that difficult to replace .  

The first question is the shape of the bolt holes? Are they still round? Is the wood solid or are there areas of rot or evidence of water damage? If the plywood is in good shape, I wouldn't replace the bulkhead. The tabbing looks pretty flimsy, maybe one layer of glass. Adding a couple of layers of glass on top of the existing tabbing might be a good idea. Sand it well and use epoxy. Adding a backing plate for the chainplates will help distribute the load better than nuts and washers. This will also reduce any movement by the bolts in their holes, reducing the possibility of the holes becoming oval.  

Project_Mayhem

dlochner said: The first question is the shape of the bolt holes? Are they still round? Is the wood solid or are there areas of rot or evidence of water damage? If the plywood is in good shape, I wouldn't replace the bulkhead. The tabbing looks pretty flimsy, maybe one layer of glass. Adding a couple of layers of glass on top of the existing tabbing might be a good idea. Sand it well and use epoxy. Adding a backing plate for the chainplates will help distribute the load better than nuts and washers. This will also reduce any movement by the bolts in their holes, reducing the possibility of the holes becoming oval. Click to expand

Project_Mayhem said: What about a tang as a backing plate and to spread the load further down? Click to expand

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Seawalls and Bulkheads

We design and build structures that protect homes by reducing the natural erosion of land by water.

The Difference Between Seawalls and Bulkheads

While the two terms tend to be interchanged, seawalls goes the “extra step” to offer protection of a shoreline from the action of the waves while also helping to ward off soil erosion. They are in place to combat pounding surf and the ferocity of waters that result from coastal storm events.

For seaside towns, this coastal defense system is typically installed to protect its citizens, but private seawalls for residential homes provide that extra layer between the homeowner’s property line and the water. Seawalls can be constructed from any number of materials like concrete, vinyl, and/or riprap; sometimes a combination of the two.

An embankment that defends the shoreline from erosion and potential flooding, you could say a seawall is simply delaying the inevitable, but when you live at the waterfront, these are steps essential to co-exist with nature and to respect those boundaries.

A more common form of shoreline stabilization at locales like marinas, bulkheads typically prove an economical shoreline boundary that separates the marina from the actual slips.

Like any structure with a percentage of its surface residing beneath the water, bulkheads need to be consistently monitored for their inevitable deterioration. The source of this deterioration is due to the natural properties of water and marine life, but even man-made issues like scour from propellers can gouge the bulkhead’s surface.

The argument to have structures like bulkheads professionally designed and built with superior materials is supported by the need for safety. Engineering bulkheads to support the anticipated traffic is particularly key as a heavier category of machinery travels them. This is the same reason why bulkheads require consistent preventative maintenance via scheduled condition studies.

Bulkhead design takes into account multiple factors – and makes for an interesting exercise in taking its installation in water juxtaposed with its need for stability on land.

To that end, besides the determination of the best material to suit for its strength and performance, a deep analysis of the marine environment where it is being installed is essential:

• Is the exposure to fresh water or salt water?
• What are the properties of the soil for the embedment? Is it clay or sand, and what is the unit weight of these materials, how does that factor into stabilizing the bulkhead?
• What elevations and grading need to be calculated?
• What is the water table measurement?

Hire a Professional Marine Construction Specialist to Build Your Seawall or Bulkhead

As marine construction specialists, there is no shortage of reasons to hire a professional to build such structures. It is just as valid to hire a contractor to inspect and repair both seawalls and bulkheads to maintain their integrity and ensure the safety of all who use them – whether they are for commercial or residential use.

Budgetary constraints are always a consideration that can be factored into a solid solution to support either a seawall or a bulkhead – an informed analysis is what provides the best foundation.

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J22 Ives Knoll - Main Bulkhead Replacement project

Our club J22 fleet is aging and two boats required new main bulkheads.  This page documents the replacement on the main bulkhead in J22 #6 Ives Knoll due to rot at the port side chainplate.  There are also some other minor repairs documented here.

Ready for last glass work on a beautiful day

Bulkhead weakened at chainplate on port side

The first step was to create a template of the existing bulkhead.  This was done using cardboard on the previous boat (J22 #5) and we had created pressboard templates for port and stbd halves of the bulkhead.  These pieces were test fitted and some minor modifications made.  Once we were happy the chainplates and all other hardware caps and fiddles were removed from the existing template and a proper test fitting was completed.

Templates aligned on the Coosa board to cut new bulkhead core.

Pink coloured pencil was the best contrast

New core pieces cut.

Test fitting the new core pieces

The templates were oriented on the coosa core material in a manner to produce the least wastage.  Then they were traced in pink coloured pencil and cut using a jigsaw.  Back in the boat they were placed against the existing bulkhead to ensure a proper fit. A minor modification and we were happy with the fit and ready to proceed with the demolition stage.

Old bulkhead mostly removed

Old bulkhead removed. Now cleaning up leftover edges

The last bits of the old bulkhead chiselled out.  Ready for grinding

Grinding complete.  A lot of mess!

Gelcoat removed for tabbing and the mess mostly cleaned up.  Ready for new bulkhead.

With the templating process ccompleted it was time to remove the old bulkhead.  Despite being rotted at port chainplate the rest of the bulkhead and the tabbing was very strong and difficult to remove.  Tools of choice were Reciprocating saw, angle grinder with cutting disc, cordless drill, BFH (Big F...ing Hammer), prying tools, wood chisels.

Initially a 3/8 inch bit on cordless drill was used to make a hole for the saw.  Then we cut around the edges of the bulkhead and applied liberal doses of bashing with the BFH and even some prying to get rid of the bulkhead.  The process required frequent changing of blades in the reciprocating saw but eventually the old bulkhead was removed in three pieces. There was still some tabbing and some of the plywood from the old bulkhead attached at the hull.  The cutting disc on the grinder took care of the tabbing material and a wood chisel and a lot of patience removed the wood residue. 

With the bulkhead removed it was time to prep the surfaces.  The interior of the J22 is gelcoat.  This must be ground away for 5 inches on each side of the bulkhead to allow the new tabbing material to bond to the hull.  The angle grinder once again used with a sanding disc.  The process was not difficult but very messy.  It is even worse due to the cramped and low ventilation conditions inside a J22.  Following this process 30 minutes with a shop vac was required to cleanup the large amound of dust and gelcoat residue.

New bulkhead core joined with strip of Biax cloth

New bulkhead assembled and ready for installation

To say the interior of a J22 is cramped is an understatement.  For Ives Knoll we decided to assemble the bulkhead outside of the boat where the working conditions are much more pleasant.  Leaving approx four inches uncoated at the edges for the initial tabbing material both front and back sides of the bulkhead were covered with biaxial cloth.  Following this process the exposed edges of the new bulkhead were covered with 6 oz cloth.  These are the edges that will be exposed once the installation is complete so the 6 oz cloth makes for a more finished look.  We are now ready to install the bulkhead in the boat.

New bulkhead in place and ready for tabbing

First layer tabbing applied. View from forward

With the bulkhead now assembled it is time to move back inside the boat. A bit more grinding and some minor persuasion with a rubber mallet and the new bulkhead was in place.  It was a very snug fit which is great.  With the bulkhead in place the next step was to apply the first layer of tabbing to the forward side of the bulkhead.  For this we used 6 inch wide tabbing tape which is basically biaxial cloth that comes on a roll.  The aft side will have any gaps around the edges filled with Polyfair and then will also have a layer of 6 inch tabbing.  This will be followed by a layer of 8 inch tabbing (biaxial cloth) and then a full covering of forward and aft faces of bulkhead extending 5 inches out on to hull as the final tabbing.

Initial layer tabbing complete fore and aft

Polyfair applied around compression post step.  Some cleanup required

One interesting side project involved a small gap between the mast compression post step and the new bulkhead.  When cleaning up the area around the old bulkhead some edges of the forward tabbing were left in place as a guide to location of new bulkhead.  With the new bulkhead tight against these edges there was a 1/4 inch gap between the step and the new bulkhead.  One option was to tighten the bolts once bulkhead was complete, however it was decided that this would cause a bend in the bulkhead.  Instead we opted to tighten two of the bolts to the point where the fit was tight but the bulkhead not bent prior to tabbing.  Then the small gap between the compression step and bulkhead was filled with resin soaked fibreglass mat.  With this done Polyfair was used to seal the edges of the gap.  As seen in the above photo there will be a sanding required to clean this up after it cures.  Cloth will then cover the polyfair up to the edge of the compression step.

2nd layer of Tabbing cloth applied. Ready for final layer cloth

Final layer of cloth fitted and ready for resin

Final layer of cloth complete

Ran out of gelcoat!

Now that the bulkhead was tabbed in place it was time to apply a second wider layer of tabbing.  The first layer was 6 inch wide and the second 8 inch wide to provide an overlap.  24 hours later we were ready for the final full layer of glass.  This was a full covering of the bulkhead and extended its tabbing 5 inches on to the hull.  After sanding the bulkhead was still tacky so held the new cloth in place while a genourous amount of resin was applied.  Following this was a 24 hour wait for curing, a final light sanding and then gelcoat was brushed on rather than paint.  Unfortunately there was only enough to coat the forward face of the bulkhead and a small bit around the chainplates  port and starboard.  Project on hold pending the arrival of more gelcoat.

Four bolt holes drilled for mast compression post step and 2 limber holes

Port chainplate re-installed

Stbd chainplate re-bedded.  Needs screws for cap

While waiting for more gelcoat to arrive some final steps of the bulkhead replacement task were undertaken.  Most of this involved drilling holes.  First the chainplates had to be reinstalled.  The temporary caulking was removed at the deck and then using a cordless drill the bulkhead slots were re-shaped thru the fibreglass tabbing.  Then the chainplates were put in place, bolt holes drilled and bolted in place.  Once that was complete on deck the chainplates and covers were bedded using 3M 4200 adhesive sealant.  Thankfully we had enough gelcoat the previous day to apply a coat where the chainplated would sit on the bulkheads and where the chainplates would come thru the tabbing on underside of deck.  A final task was to prepare for rebolting the mast compression post step to the bulkhead and to drill limber holes for drainage.  Once the final coat of gelcoat is applied the step will be bolted in place.

Port bulkhead with slight bump out for chainplate

Bulkhead installation complete.  Just requires hardware bolted in place

Bulkhead complete with chainplates and mast compression step bolted in place.  Some cleanup required

The gelcoat supply had been replenished and we were ready to complete the bulkhead. However we did notice an odd thing.  This J22 had a bulkhead that was thicker than the previous one and we were using the same stock for bulkhead core.  This resulted in a finished biulkhead whose aft side was approx 1/8 inch forward of the chainplate holes in the deck.  Due to this there was a gap between chainplate and bulkhead where bulkhead meets deck.  The chainplates were removed, the painted on gelcoat was sanded off and a patch four layers thick of biaxial cloth was built at chainplate locations port and stbd.  In the picture above you can just see this bumpout that removes the gap.  With this complete the aft side of the bulkhead was brushed with gelcoat and the bulkhead installation is now complete.  The chainplate needed to once again be installed and bedded and the mast compression step bolted to the new bulkhead.

Gunwhale Repair

Aft section was in the worst state

Forward the damage was less severe

There had been some damage to the port gunwhale in four separate places.  Two places were simply cracked gelcoat while the other two were through to the layup material.  The section that was aft actually was cracked completely through with the fairing material beneath crumbling while the forward section was surface only.  The two small sections with cracked gelcoat need only to be ground faired and new gelcoat applied.

Aft section with damaged material ground out.  Nasty

Forward section cleaned up and 3 layers 6oz cloth in place

Aft section with 5 layers cloth

The two main areas were ground to remove the damaged material. The one aft had crumbly fairing material inside a hole.  This was dug out and replaced with polyfair and then five layers of 6oz cloth were applied.  We could not get biaxial cloth to lay flat over this bend so 6 oz cloth was used.  The forward area had 3 layers of cloth applied and looks ready for sanding and fairing.  The aft section needs to be built up with  bit more cloth before it is faired.  The other two minor sections require fairing material only.  This will be faired using coloidal silica mixed with polyester resin for added adhesion, strength and for its white colour. 

First fairing coat applied. It is not white

Port Aft Gunwhale area faired and sanded

Port Fwd gunwhale area faired and sanded

One more layer of cloth forward and another aft was applied.  Next West 406 coloidal silica was mixed with the polyester resin as a thickener.  The intent was that it would be white but instead the colour of the resin won out and the result was an aqua colour.  The thickened resin was applied to the four repair areas to fill any hollows and then sanded.  A second very thin layer of fairing compound was then applied almost as a skim coat.  Once this is sanded the areas will be coated with white gelcoat and sanded with 220 then 400 and 600 grit.  Following that rubbing compound.  It is our hope that this will blend in with the hull more or less.

Fairing coats complete.  Gelcoat brushed on

Closeup shot of repaired area.  Close but not exact colour match

Another shot this time from aft.  All four repaired areas are visible in this picture

Miscellaneous smaller repairs

With the major problems addressed we now had to turn to some smaller tasks that needed to be done prior to using the boat.  These included rebedding stbd jib track, relpacing stbd cam cleat and drilling and refilling the many holes on deck, in cockpit and on sea hood where hardware had at one time been installed. Once this is complete the bottom will be cleaned and painted and then the boat will be ready for the water.

Sea hood holes drilled and ready for fill

Sea hood holes filled with thickened resin

All the holes filled and ready for sanding

The deck, cockpit and sea hood of this boat had a larger number of holes from previously installed hardware.  Most of the holes had been sealed with resin but were not flush with the deck while those on the sea hood and cockpit seats had been filled with silicon and had some water intrusion.  Our plan was to drill all holes slightly larger, fill with thickened resin and then sand flush.  Any water in the core and associated rot would be addressed at a later date.  The good news is that all of the holes in the deck were filled with resin and water tight leaving only the sea hood and some areas of the cockpit with possible wet core.  In the above pictures you can see holes on the poop deck, cockpit seats forward of the traveller and less visible near the toerail and on bow.  This boat at one time had stanchions, pulpit, pushpit and lifelines.  When added to the sea hood that makes for a lot of possible places for water intrusion.

Starbord jib cleat needed to be replaced

New jib cleat in place

J boats usually have a cam cleat on a bulkhead or coaming beneath the winches for sheets and halyards.  The J22 is no exception.  The starboard jib cleat was broken and missing parts so was replaced with a shiney new cam cleat.

Fasteners for starbord jibtrack. 2nd bolt from front broken. The aft ones we had removed for bolt sizing

Jib track holes drilled larger and wet core dug out

Holes filled with thickened epoxy and sandy flush

Holes redrilled for installation of track

The starbord jib track had one bolt broken and showed obvious signs of leakage.  The track was removed, holes drilled larger, wet core dug out around edge of hole using an allen key.  Once this was completed the holes were filled with thickened epoxy, sanded flush with deck, redrilled for fasteners and the track rebedded.  Water can no longer get into core around these bolt holes

Ives Knoll washed, waxed, bottom painted and ready to go back in service

Frers 33 Persistence

J27 Nut Case

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Proper way to tab bulkheads on a fiberglass boat

Discussion in ' Sailboats ' started by peterchech , Apr 25, 2012 .

peterchech Senior Member

If you look at a production boat like a Hunter, many of the structural bulkheads are tabbed in with one layer of glass roving. I don't see what looks like filler at the actual joint. I guess this is to prevent "hard spots", however that works... On a better quality boat like a C&C, it looks like they use several layers of maybe 10 oz regular glass. Being opaque, I can't tell whether there is filler at the joint or not. Say I wanted to add a structural bulkhead to my boat, or else reinforce an existing one. What is the best/proper way to attach the bulkhead to the hull of a glass production boat?  

souljour2000 Senior Member

I am not sure... but we will hear from the experts...I will say that I think a small fillet along the tabbed areas with a few layers of glass over it would be needed to reduce any bulkhead movement and seal joints to reduce moisture migration ...sealing the butt ends of the ply with epoxy is critical so it doesnt wick up moisture. Then consider leaving a small gap at where bulkhead, etc. panels meet the hull/coachroof that can be sealed as part of the epoxy fillet...and then tab over with light/heavy glass layers...  

gonzo Senior Member

It depends on the hull construction. Cored hulls don't usually get print through from hard spots. If the laminate is solid, it is common practice to either leave a small gap or have a foam tapered filler in between.  

What kind of foam would be used as filler? Mixed floation foam? Seems that would expand too much...  

iceboater Junior Member

I use carriage bolt (photo1) of different size to shape fillets from fiberglass bonding paste (photo 2) from Oldopal. I am not familiar with using expansion foam as filler, I think Gonzo means pre cut foam fillets. For glass over the fillet, I use any ware from 1800-4500 gr/m2 of glass (sorry, metric) tapered out each layer depending on the design. Axel  

Attached Files:

Screen shot 2012-04-25 at 9.39.27 pm.png, screen shot 2012-04-25 at 10.54.22 pm.png.

Yes, I meant precut foam fillets  

PAR Yacht Designer/Builder

A typical foam shape, used under the edge of a bulkhead, at the interface of the hull shell. Triangular shapes are common as are trapezoidal stringers. Any shape can be cut, though these can save time. A filler can be mixed as well, which serves the same purpose and commonly applied as a fillet or bedding under an element. As far as proper tabbing, well it depends on the loads. A single layer of fabric isn't uncommon. This doesn't mean it's very durable, just that it's an out of sight place manufactures can save some money. Directional fabrics are much better suited to tabbing than anything else. It's all I spec except on small craft where cloth will serve. If you could be more specific about your application, more precise answers could be applied. What ever it is, I'll probably tell you to use biax and epoxy, no mat. It's just easier, stronger, uses much less resin and isn't going to fail easily. As to how much biax, well this depends on the boat and the bulkhead.  

Well I ask for two reasons. I have a 1982 hunter 25 and have repaired cracked bulkheads on it before.I used the same method as I would on a s&g dinghy. An epoxy and hard filler joint, filleted to about 1/2 inch half round, then 2 layers of 10oz glass cloth. I was wondering if this is adequate, or whether the epoxy filler joint would create a hard spot or even a stress concentration point. The second reason I ask is because the owner of the Phrf boat I will be crewing on ripped out his interior and installed a "grid" of shallow bulkheads around the keel intersection area. I like this idea alot. I was wondering what the proper way to tab them into my boat would be, since his is an aired cored hull and mine a thin (hunter) solid laminate. Why bias tape? Don't most s&g designs call for regular old tape? An idea on the proper layup would ne helpful too...  

Steve W Senior Member

When you use regular 0-90 glass tape only half of the fibers are running across the joint,with double bias tape all of the fibers cross the joint making for a much stronger joint. As Par pointed out how much glass you should use depends on the application,if you are tabbing in a main structural bulkhead such as the ring frame under the mast you would use more glass than a piece of furniture. For some applications just a large fillet will surfice. We do maintainance on a 40ft cold molded race boat that has some bulkheads just filleted in and after 30 years,so far so good. Steve.  

SamSam Senior Member

iceboater said: ↑ I use carriage bolt (photo1) of different size to shape fillets from fiberglass bonding paste (photo 2) from Oldopal. I am not familiar with using expansion foam as filler, I think Gonzo means pre cut foam fillets. For glass over the fillet, I use any ware from 1800-4500 gr/m2 of glass (sorry, metric) tapered out each layer depending on the design. Axel Click to expand...

Another trick for glassing bulkheads with heavier fabrics. We made 30' powerboats AquaMarine Island Hoppers) and I had to tab the bulkheads to the hull. We used Fabmat, which was 24 0z woven roving glued to 1 1/2 oz mat. The 8 & 12" wide strips had to be cut at chines and strakes to conform to the hull and the fabmat was too thick to wet out from one side. So the procedure was to lay it out mat side up on cardboard, wet that out, flip it over and wet out the other side, pick that up, stick it in position and roll out the bubbles. By the time you got a 5' section all wetted out, the mat on one side had begun to dissolve and the WR on the other had begun to un weave itself. With all the cuts to make it conform to the hull shape added in, laminating at all was tough, neatly was not possible. All this was in open hulls in Florida sunshine. After a few boats I started putting the Fabmat in place dry. I would then fold down the vertical halve on the bulkhead, wet out the mat and ply bulkhead and stick it back in place. Then I would fold up the portion on the hull and do the same. Then I would wet out all the WR side and roll out the bubbles. It worked perfectly and 'looked marvelous'.  

Fabmat and stitchmat products are really a waste of resin (lots of it) in an epoxy laminate. In polyester structures a necessity, but not epoxy. The real reason biax and other directional fabrics are better suited to tabbing is simple physics. Conventional cloth is woven, with the fibers going over and under each other. Under load these fibers have to flatten out, which kinks and weakens them, long before the max elongation of the resin or fibers are reached. With directional fabrics (like biax) the fibers lay on top of each other, essentially being continuous straight lengths. Under load these fibers immediately begin to participate in resisting elongation, so the resin and fibers work in concert without delay, kinks or flattening out first. Small taped seam craft can employ regular cloth on their seams because it's more then strong enough to reach the peel strength of the surrounding wood it's bonded to. This is especially true on the outside corners of a taped seam. On larger craft, loads can exceed what cloth can provide, so direction fabrics are necessary. Generally, bulkheads are highly loaded in all but the smallest of boats. The use of biax is the best way, to use the least amount of resin and fabric, to achieve the desired strength and stiffness. Fillets prevent stress risers and hard points, again from simple physical laws. A stress riser is created when you have a sudden and dramatic increase in density along a panel or element. If you have a plywood planking panel and a bulkhead perpendicularly joined to it, loads traveling down this panel reach the bulkhead where there is a sudden and distinct rise in panel stiffness and density. the edge of the bulkhead makes a hard point as the load transmits through it, which can cantilever on the adjoining planking panel. If you can ease this transition area with a ramp, such as produced by a fillet, the load transmission area, is spread out over a much wider area and the density increases more slowly. This helps dissipate the load into the adjoining panel, without a hard point, releasing strain on the joint, the planking panel and the bulkhead. As to your tabbing concerns, two layers of 10 ounce doesn't seem like much. I scale tabbing to the loads anticipated. On a boat the size of yours, it would surely be biax, not cloth. Also if in doubt about the creation or elimination of hard points, error on the too big side with fillets.  

SamSam said: ↑ Another way is to slip the appropriate sized tool socket over your finger and drag that along the filet. A really good tool is a ball bearing welded on a rod. With that you can go into a three way corner (like the inside bottom corner in a box) and all the fillets can be done at once and will match perfectly. Click to expand...

Steve W said: ↑ SamSam, such a tool can be purchased from pattern shop suppliers such as Kindt-Collins or Freeman Supply with different size balls on each end, they are chrome plated and are typically used for working leather or wax fillets into a corner. Actually there are a lot of things used in the pattern making industry you guys may find interesting such as the leather fillets and carvable polyester filler and castable urethanes. Steve. Click to expand...

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PAR said: ↑ Fabmat and stitchmat products are really a waste of resin (lots of it) in an epoxy laminate. In polyester structures a necessity, but not epoxy. Click to expand...

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Sailboat bulkhead material and Location

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I'm really using this forum to gear up for a project, thank you very much. Marine plywood versus standard pressure treated plywood as an alternative for a bulkhead material? Marine plywood needs to be shipped in from Seattle...I can grab a sheet of 3/4" pressure treated right off of the shelf. Any issues with this that folks can comment on? Follow up, I've been reading about some folks using a fiberglass G-10 panels in a West System write-up as well for an alternative. Also, Location....is there any reason not to remove a bulkhead while the boat is in the water....structurally or is this a boatyard repair. I can shore up the lateral as required, however without load...mast removed and shrouds not connected, cabin deck supported internally...is there a flex issue with the boat simply floating without a main bulkhead?  

I replaced my starboard side bulkhead recently and used marine plywood because I had ready access to it for a fair price. In retrospect, I am not sure it was necessary because I ended up coating the piece with epoxy and strengthing areas with additional layers of fabric. The marine ply is clearly superior to the standard and I have a greater level of confidence in the repair. Also my boat is 7.3 meter and will not have the same load as your Cal. West Systems Epoxy Works had a good article on a bulkhead repair where an even more $$ and exotic material was used  

Yes, I read that article and looked at the composite board material! $$ is right....but bulletproof. Thanks.  

Thanks Sailingdog. Great point on the toxicity. I was thinking simply on durability and not that I'd have to be living next to it.  

Marine plywood has a couple advantages ...extra ply and no voids..been told same glue is in exterior ply so thats no better...but for a bulkhead that will be reinforced anyway I would not pay special fright and or wait for it to arrive just to have it but would go with 3/4 inch cc plugged ex tier... Pressure treated ply also is not as stiff due to the impregnation process...it warps a lot easier under loads...so I would not use it for a bulk head...I wish Bayliner would have used it for transoms in their boats though...they would not have such a rot issue... You will be fine pulling your main bulk head under the conditions you listed still in the water...  

My feeling on these type of questions is that the labor of the job (your time)is exponentially more expensive than the materials and often you are short changing yourself by choosing a less expensive material over the one you know is better. Just my two cents but I have found that after spending 80 or so hours (WAG) on a job like this it's easy to regret saving $50-75 or so bucks for cheaper materials. Good marine plywood cuts much cleaner, the plys are usually finer grain, is vastly stiffer as Stillraing points out, has no voids, and will provide the right answer for the next potential owners survey. Whichever way you go, good luck with the project  

I can understand the difficulty you face, if the proper material is not available. Would your supplier be willing to put a few sheets of marine ply on his next shipment of material, and perhaps split the freight with you? Whatever you use, I would echo the others and say use the best you can get your hands on. It isn't an easy job to begin with, and it would be a shame to see first class labor with second rate materials. From my own expierience I would advise that once the piece is cut and test fit that you seal all the edges with thickened epoxy, two coats is best, and then tab to the hull well. Your bulkheads may never have rotted if the edges were sealed well. Wooden boats can funcion well indefinately with water inside, but plywood fairs poorly to being even damp for long periods. Do the job well and be pleased with the result. Feetup  

Great stuff guys....thank you very much. Marine Ply it is an take my time.  

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Replacing the Bulkheads in my Tanzer 22

Why replace the bulkheads.

When I had my Tanzer 22 surveyed, the report noted that there was some delamination of the plywood of the bulkhead due to moisture. Both sides have had water dripping in from the chainplates and both sides have had some water damage at the base.

Since the bulkhead support the chainplate which can put alot of tension on the wood, it's better to be safe than sorry, so I need to replace the bulkheads, and the bent chainplates.

The bulkheads also support a wood beam inside the fiberglass. This supports the mast and can have a lot of weight put on it when the boat is underway.

There is some damage on the bulkhead at the very left. The drips from the chainplate are also visible. My Tanzer has wood veneer not the plastic I've seen on some of the other boats.

There are 3 slot head bolts at the very top that need to be removed. As well there are some bolts inside the locker just back of the bulkhead.

There is also a moulding that run from the ceiling to the floor, 4 screws hold it against the bulkhead. it's strong enough to have some part in supporting the deck and mast above.

Nice easy to access nuts and bolts in the locker behind the bulkhead.

On the starbord side these bolts are under the sink and will be a tight fit to remove.

Small Mystery: Why is there a notch cut into the bulkhead on both sides of the boat. For curtains? Wiring? There is no structural reason that I can see.

Some damage to the outside layer of the veneer is visible in the corner. On the right the chainplate is clearly bent. This photo is of the starboard chainplate. The bottom image is of the slot where the chainplate goes into the interior. it's easy to see how it could allow water to get in if it's not perfectly well caulked and bedded. There was probably some water coming in after the chainplates were bent.

The chainplates get bent when the mast is lowered without loosening the side stays. If the metal is bent back it can cause metal fatigue so it's better to leave the chainplate bent than to try and straighten it back.

View from the front of the boat shows the fasteners. There is also some wiring to be removed, the lightning rod wire, and light fixture wire.

The chainplate backing plate is still in place. It has 4 nuts and bolts. (I took this photo before removing the chainplate)

Once all the screws were removed including the ones holding the wooden moulding in place it was simple to slide the bulkhead out. I wedged the moulding so it pushed up on the roof slightly. This allowed the bulkhead to slide out without any trouble.

Since the mast has been taken down for the winter storage there is no weight on the top of the cabin. I avoided walking on the top while I was doing this repair. I don't know if it matters.

I was worried that the roof might sag when the bulkhead was removed but that did not happen. I left the moulding in place to support it just in case.

I was also worried that the bulkhead would be wedged in place by a sagging deck but that is not the case. The good guys are winning again.

The plywood I removed was not in terrible shape. The chainplate holes were dry and the wood was not delaminated except for the thin veneer on the top. There was also slight discolouration on the very bottom where it had at one time stood in water. It is 3 layers thick with 2 very thin outside veneers.

I took the piece home where I have a piece of Meranti nice and flat on my dinner table waiting to be shaped. I had kept it from the Apple Pie Dinghy build.

The space looks very large and empty now that the bulkhead has been removed. I've left the moulding up to keep the roof from caving in! I'm joking, but I want to avoid any distortion that would make it harder to replace the new bulkhead.

Here is a link to my page about Marine Grade Plywood. There are very stringent requirements to be met if it's to be true marine plywood.

Now I need some information. Can I get a chainplate from Tanzer Parts, or do I just go to a metal shop and have them make me a replacement? I would like to know what the funny little cut out in the side of the bulkhead is for.

Since I hate slot screws with a passion, I will see if I can replace the original ones with Robertson head. It might be difficult since it looks like the originals were cut to fit. Maybe it's not a standard size.

I carefully aligned the old bulkhead onto the Meranti Plywood. it's 12mm I think, It always feel a bit silly to order a 4 feet x 8 feet x12 mm. sheet of plywood. Talk about mixed up units. The outer edge that is covered by the moulding is the only non beveled edge except for the little cut out. Every other edge has a slight angle. The sides are not straight either. It looks like someone took a sander or a grinder to fit it in the original Tanzer shop.

After marking the perimeter and all the bolt holes marked I asked Winston to inspect the piece before cutting. I then clamped the wood to the table. I drilled 2 of the marked holes at each corner of the bulkhead, to have a way of aligning the pieces after they are cut so that I can re align them with no shifting.

I used a jig saw with fine teeth blade. It cuts without leaving a burr. I guess it's slower than a regular blade but this plywood is brittle and the edges chip and tear out if the blade is coarser. On the Skerry build I used metal blades sometimes. It was slow but clean.

To make the bevels I used a combination of my random orbital sander, a file and sandpaper on a block and my hand plane. it's tedious to shape. My little plane worked in some places but others it was too hard and on end grain and the sander was faster.

New bulkhead piece is cut out and beveled. Tomorrow I will take it to the boat and spend a happy afternoon fiddling to fit it. I have no illusions that it will just slide in. After the fitting I know I will need to make it slightly smaller because I plan to epoxy and varnish the bulkhead and this will thicken it up again.

I've located a few machine shops nearby and I will now call them and see if they can fabricate new Tanzer Chainplates. I will not make it bigger. There was no sign of stress on the bulkhead and no distortion of the screwholes so I don't see the need. I will also not use thicker and thus stronger metal because I think I prefer to see damage on the chainplate where it is easy to spot than on the mast fitting or the stays, where damage might not be so obvious and more expensive to fix. When there is a lot of stress something has to give, I prefer to know what.

Should the chainplate fail there is always a chance of grabbing the end and tying it down to something on deck. There is no chance of doing this if it fails from the top of the mast.

The colour of the Meranti Plywood looks grayish but comes up a rich brown colour once finished as on my Apple Pie tender transom. I painted over the epoxy but the colour was very nice.

My day job interfered with my life and I did not get to the boat. I did get the chainplates made though.

I had left the original damaged chainplate at a machine shop near my home.

The shop is quite high end but so conveniently close that if I count even a fraction of my time it's worth paying a slightly higher price.

They did a fabulous job and the new Tanzer chainplates are absolutely identical except for the finish. They put a bit of a satin sheen on. They look very classy!

When I brought it in the owner said that there would be no problem making the part and that most of the time would be spent drawing the part in a CAD program. The actual machining is very fast and automated.

The shop is immaculate and the floor is full of huge automated cutters, lathes and tempering gismos. They also have a hands on room with more recognizable equipment and men who actually get dirty hands.

After drilling the various holes, I wrapped the new part in an old sheet and took it to the boat to check the fit. It was almost right. I need to allow for the slight curve of the angles of the fiberglass and cut a bit off the edge.

I also checked the mast head to see if the stays or the mast connection was damaged at all. I was worried that the wire might have pulled out of the connector. There was no damage and the stay was in good shape.

I still need to round the edge to accommodate the radius on the fiberglass.

The top edge also needs trimming to fit against the fiberglass rounded corner. Since these 2 edges won't be showing it's not too stressful.

The boat cover makes a tent and it's surprisingly warm and cosy inside. I can sit on the seat without touching the roof. When it gets cold and I want to work on the boat, I can set up a small heater.

I took the bulkhead home and sanded it slightly smaller and rounded the inside edges. After testing it for fit I'm happy. The bulkhead is quite tight but fits. I took it home and did a final adjustment to allow for the epoxy thickness and some varnish.

Sanded all the holes smooth. There was some burr left over after the drilling. Used a small file and rolled up sandpaper.

Sanded the whole surface and erased any pencil mark still on the edges.

I thinned the edge that has the trim so it will still fit in after the epoxy and varnish. Dusted everyting and I think I'm ready for epoxy.

Put the epoxy in warm water to warm it up after coming in from the cold garage. I'm using slow set to let it penetrate as much as possible. I like having lots of time to apply the epoxy without worrying.

Used a small paintbrush to coat all the drilled holes with epoxy. In particular the chainplate holes were saturated. If water ever comes in it won't ever get wet.

The Tanzer bulkhead now has a coat of epoxy on both sides (I used small nails stuck in the table to support the back side)

I paid particular attention to the edges to make sure they were saturated. I love to see the wood come alive after the first coat of finish. it's a lovely rich brown. Photo is a bit blotchy but it's quite even.

This is the point in the project where if I had to I could put the boat back together and it would work just fine. The rest is for appearances.

I was calculating how long I had spent so far. Take the bulkhead off the boat: 1 hr Mark it and cut 1.5 hrs Bevel the edges and fine tune the edge 1.5 hrs 2 tests on the boat and adjustments 2 hrs final sand and epoxy coat 1 hour So far a total of 7 hours, but no rushing involved. So this job takes about 12 hours at a leisurly rate completely re-assembled not counting getting the materials. I had all that from the floor repair. If I had done the 2 sides at the same time it would have saved time but I prefer to have some support on the bulkhead in case there is some sagging.

I've had enough of sanding epoxy. it's pretty smooth now. I've re-drilled the holes where epoxy had thickened the opening too much. I've tested the fit in the boat again and it's good.

it's interesting that the top had settled very slightly. I will be able to push it up but it had come down about 2 mm. I'm glad I left one bulkhead up and a support as well.

I'm using Behr spar varnish on the carefully dusted bulkhead. The colour is slightly browner than the original but it's a lovely colour. I'm planning to put several thin coats. I'm in no rush to finish.

First coat is on and drying. it's going to look nice on my little boat.

After several coats of varnish, I dulled it with extra fine steel wool and waxed it. The bulkhead feels lovely and has a nice dull shine. it's far from perfect but will pass the 4 feet rule. If you can't see a flaw at 4 feet it's good enough!

Finally a lovely sunny day and I brought the bulkhead and starting installing it on the Tanzer. I had to push up the top a small amount but there was no real difficulty. My port navigation lights have little screws protruding and one was digging into the bulkhead. I had to go unwrap the boat and unscrew it. I'll replace it with a slightly fatter and shorter screw that does not extend into the bulkhead.

I used an awl to line up the screw holes. It worked well and I got all my bolts in place. They all lined up perfectly. Beginners luck!! I though I would have to re-drill some but I got lucky. I intend to replace some of the bolts. The originals were slightly bent and seemed to have been cut to size from longer bolts. The chainplate hole was gummed up with old silicone. It took a long time to clean it up. When I can access the outside more easily I will clean up on deck and put 3M 4200 to seal the chainplate and the hole.

The lower nuts and bolts are in place as are the top ones. I plan to replace the top ones. The chainplate is loosely bolted in. All the holes lined up perfectly and the bulkhead fits. I tapped in the edge moulding but I plan to refinish it after the 2 bulkheads are installed. Right now I prefer to have it supporting the deck

The Starboard bulkhead is more damaged but I did not realize the extent of the rot.

Starboard Bulkhead

From the outside there seems to be minimal damage but once I took the bulkhead off the inside was quite rotten. The delamination is not severe except for the thin top veneer. There is rot for about 2 inches around the corner. The rest of the wood is quite strong. I'm wondering if some of the water came from the sink along with the leaky chainplate.

It was a bit trickier to remove this side because the sink is in the way and it's awkward not being able to stand nor sit. The nuts live under the counter too. The worst was my mistake. The outside moulding from the port side was held on only by screws. The starboard one is held by screws AND a nut and bolt. It took a while to figure this out. sigh!!! I thought the screw was not catching and just turning freely.

Spring is almost here and there is still lots to do with with boat. I'll get this bulkhead done more quickly now that I know how.

Launch looms closer now. I have completed the starboard bulkhead and sanded and varnished the vertical wood strips that trim the edges. Everything fits.

Everything went together quite well. I had to do a couple of fittings to get the bulkhead to slide in but nothing major. The trickiest part was putting the nuts on the bottom. There is not a lot of space between the sink and the bulkhead to hold the nuts. It's not hard particularly just fiddly and I kept dropping washers and having to hunt for them.

I removed the chainplate deck fittings and found that they had been seated with silicone. it's always difficult to remove all the old stuff and I had to scrape and sand the deck and the slot. I'm sure I left some inside the slot.

I put an extra large dollop of 3M 4200 and replaced the chainplate and secured it from the inside. I then gooped up around the chainplate and replaced the now cleaned fitting. I made a mess but I think I got the plate down and I don't think this will ever leak for as long as I'm alive. I was using compounds that had just began setting off so it was slightly thicker than when it's fresh so it resisted coming out of the tube. My inside caulking is not so very nice. It was setting quite quickly so I did not have lots of time to fiddle and clean as I went.

I finally got everything back together. The new bulkheads, the new chainplates waterproofed, all the screws and nuts tightened and the wood trim glued and screwed back in position.

I guess I will go back and tidy the caulking after it has set, but for now, I'm done! The good guys win again!

Small Print

This information is for general knowledge. I don't suggest that this is the only way or the best way to fix your bulkheads. Use your head and do your research.

Attainable Adventure Cruising

The Offshore Voyaging Reference Site

• Watertight Bulkheads

One of the things that is attractive about metal construction is the ease with which structural modifications can be made. What would require substantial amounts of design, planning, physical work and cost in a GRP boat can require very little effort in metal, whether steel or aluminium.

A good example of this is the installation of watertight bulkheads. When we had Pèlerin constructed we specified an additional full depth watertight bulkhead aft of the anchor locker. As the angled back wall of that locker already formed an effective watertight bulkhead it might seem to be overkill to add a second one, but in fact the anchor locker bulkhead is too far forward and so doesn’t extend far enough below the waterline, and as there was already a designed ring frame behind it, (a) we weren’t going to lose much additional space and (b) all that had to be done was provide a plate to ‘fill’ the ring frame to make it fully watertight.  The cost was in the order of $100—negligible on our boat.

Our thinking was that in going to this extra length we were forming a double crash bulkhead that would absorb a head-on impact far more effectively. It would also be much more likely to retain full watertight integrity, which was, of course, our reason for going down this route in the first place. And with an additional watertight bulkhead aft as standard we had the best of both worlds.

Are they a must-have?

No—as John has pointed out in a very well argued earlier post , it’s important to understand the limitations of watertight bulkheads, especially when considered in light of the few sinkings caused by collisions with floating objects. But, in my view, the addition of watertight bulkheads is still worth considering if the cost and complexity equation is favourable, as it was in our case.

And whilst I’d agree that they won’t make a boat unsinkable, they will buy you time in the event of a major collision, perhaps allowing you time to effect a basic repair to reduce the ingress of water, thus preserving batteries so that you can get out an appropriate call for assistance via sat phone or VHF/DSC radio. Or, in the worst of scenarios, buying you time to abandon ship in good order. I don’t think that’s in any way a negligible advantage—quite the opposite.  And if I were to build or specify another new boat, would I do the same again? The answer is emphatically yes, and here’s why.

They could save your skin

In the event of a collision that causes significant water ingress, then your primary aim will be first to stop the water coming in and then to get it out. Consider that a collision might well occur at night and/or in a less than calm sea, and you are definitely going to be up against it, especially if you are short handed.

Let’s throw in the physical challenge of stopping the water coming in and then getting it out (even with the boat stopped), as the batteries fade and the strum boxes clog. It won’t be long before you’re faced with the unpalatable choice of getting out a mayday call before it’s impossible to do so, launching the liferaft and gathering up panic boxes and grab bags and abandoning ship—and now you’re really on your own. To me, whatever we can do to stop the water coming in, even if we’re only buying time, has to be a very good thing indeed—and that’s when a watertight bulkhead might well save your skin.

Of course, that’s a relatively easy choice to make if it’s an easy option (as it was for us). And, even in that case, there are other things worth serious consideration:

• It’s a lot easier to design and install a simple solid bulkhead, i.e. without the need to physically pass through it. On some GRP boats where the bulkheads are structural features, the only possible bulkhead capable of being converted may be the one between the saloon and the forecabin. To do that it will therefore be necessary to add to the cost and complexity by adding a proper watertight door. Not only that, the tabbing and bonding of the bulkhead itself may well have to be beefed up to give it sufficient structural integrity to withstand the massive amount of water on the other side of the bulkhead.  And watertight doors are only of any use if you keep them closed, which may make them totally impractical for anything other than a military vessel!
• Unless you’re planning to undergo a seriously major re-fit, installing a watertight bulkhead on an existing boat is probably be out of the question. But one simple option might be to reinforce the bulkhead abaft the anchor locker, which will at least give some protection. If it is fairly deep and extends well below the waterline, well and good.
• Another option might be to convert the underbunk space in the forecabin to a ‘crash box’ with the inclusion of some form of structural foam to keep the water at bay even if the external shell is breached. This is one of the few modifications that can be relatively easily achieved with an existing boat, although some locker space will be lost. But I have heard a couple of reported cases where this simple modification has proved to be a life-saver.
• Any watertight bulkhead must be just that—watertight. By which I mean with a minimum of holes. Consideration should be made at the design stage about ways to minimize the number and size of holes to allow the passage of pipework and cabling, to make provision for top quality cable glands to seal them and (at the very least) pass them through the bulkhead at the top.
• Some people debate the value of a watertight bulkhead in the stern. Where such bulkheads certainly have a place is aboard a boat with a spade or transom hung rudder, where a massive impact upon the rudder might well cause the hull to be ruptured around the rudder tube or mountings. Obviously on such a boat the watertight bulkhead will need to be ahead of the rudder post, and the same attention paid to the passage of cables and pipework paid as above.

There’s a strong and valid argument that watertight bulkheads are not essential for an average cruising boat that spends most of its time sailing within relatively easy reach of assistance. For a yacht that will spend more time well offshore, in my view the argument starts to tilt towards acceptance. And for an ocean cruising boat, especially one that will go, say, polar, I’d argue that the case for their inclusion is hard to resist. Even if it only buys you time, those might be the most precious minutes of your life.

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More Articles From Keeping The Water Out:

• Do We Need Watertight Bulkheads?
• Keeping The Water Out—Topsides
• Keeping The Water Out—Deck
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• The World’s Best Bilge Pump Switch
• Positioning of Wood Plugs For Seacocks
• Bilge Alarms And Monitoring

Clearly, we are of one mind on this. If I hadn’t bought a steel boat with a collision bulkhead, I would have considered installing one. As you said, the pluses outweigh the minuses, the biggest one of which is having to go on deck to get into the forepeak workshop space. I am debating the wisdom of a watertight hatch just under the deck from the salon to the workshop, allowing bad weather access (the forepeak hatch is steel, too, and is heavy), communication with the crew, and the ability to do stuff like work on a boom end inside the boat.

I don’t wish to defeat my own purpose, however. On the other hand, I am not convinced that I have so much reserve buoyancy in the bow that smashing a below-WL hole in the bow would actually put water more than one foot above the current WL. Some math may be in order, but it’s from a happy place.

We also have to go through a deck hatch to gain access, and it’s a pain, but at the same time, it means we don’t have to a water tight door, which would have been far more weight and cost, and is potentially less reliable.

Still a good idea in my view.

Best wishes

A pair of decent gas struts would probably assuage my grief, that and some rounded off EPDM gasketing on the rather sharp metal lip of the inner hatch.

Anyway, I noticed at least part of your bulkhead seems to be angled to route the chain…great minds, etc.:

http://alchemy2009.blogspot.ca/2009/12/well-grounded-anchor-well.html

I couldn’t agree more. One forgoten chalenge is to make it safer under the tanks that normally are placed along the hull. When you get a damage under one of that tanks it is almost impossible to be able to reach the damage for stopping the water flow as the tanks are in the way. I do own a GRP boat that it isn’t very easy to build water tight bulkheads. But there is diferent ways to help to at least slow down a possible water intake due to a collision. The idea with a flexible watertight coat of foam is great and I am already considering it in some places. Thanks. One thing to take in consideration is also not forget that it is important to easily reach the all parts of the interior hull for a quick reparation. Looking forward to read the next post. Best regards from Sweden

many good points, and one in particular that stands out, that with many GRP boats it can be very difficult indeed to get to underwater damage, due to internal tanks, or more likely internal mouldings. On our last boat that was the case, and it isn’t ideal, by any means.

But as you say, there are things you can do, and that’s not negligible.

I once had the misfortune of just such a rearward rudder crash on my Cal 28. The shaft ran through a fiberglass tube, tabbed to the hull and cockpit floor. The momentum crushed the hull tabbing, allowing a difficult to slow inflow of water. In hindsight, a small crash box could have been built in the space and not interfered with day-to-day operations.

Sounds like you were lucky to get away with it – and with a relatively minor modification, you can mitigate against it.

Dear Colin, Well argued and very reasonable. One of the implications is that all your chain/rode (maybe for 2 anchors) is in the bow at all times. On a 40 foot boat, this can be quite a load to have at the tip of the boat. I know there would be a piece of me aware (and annoyed) at the sailing/pitching compromise induced by this weight in everyday life even on Alchemy, a beefy 40 footer. On Alchemy, where a watertight bulkhead is not likely for all the reasons you specify for a GRP boat, we pull the ½ + of our chain that we rarely use to amidships. When you can’t have something, it is good to look at the bright side of these compromises. I appreciate the brain teaser as well. It took me a while to figure that the picture was not: 1. The bilge pump in its recess with hoses out the side, 2. The windlass motor IN the anchor well, but 3. An extremely nice design having the windlass motor in the more benign (and accessible) cabin environment while the working windlass is in the anchor well. Thanks for the article, Dick Stevenson, s/v Alchemy

Our set-up is not quite that bad, as we have our second anchor and cable in the sail locker which is behind the watertight bulkhead, so not right forward.

And due to the fact that our hull bottom is filled with lead or tanks, we can’t store much in the bilges, although I totally agree it’s a really good idea.

And yes, the windlass is well sited – a neat job, well executed by the builder.

Nicely put, Colin. Thanks.

For what it’s worth, the trimaran I’m currently building has three WT bulkheads in each outrigger, in addition to two full ones and three partial (below the self-draining sole) ones in the main hull. If they’re strategically placed from the start, when the boat’s still on paper, it’s possible without much of a compromise in accommodations or storage. And, in our case, the incremental cost is negative; a full flat bulkhead is, for the section shapes in this boat, easier and simpler to install than a ring frame despite using a bit more material.

Hi Matt, The best way to build a watertight bulkhead is to take off the ballast keel. LOL

On a catamaran or trimaran with a thick core and judicious placement of foam flotation under the cabin soles and in non-usable areas like the narrow bows it is entirely possible to design a vessel that can still sail slowly and motor with both hulls punctured and flooded.

Hi Matt, Richard

another plus for new build, and multihulls, and foam in the right places could make for a really safe boat.

I agree with what you have stated in your post. Being a fiberglass boat owner, I do not have a proper collision bulkhead but I would definitely feel better with one.

Your point on making the watertight bulkhead truly watertight should not be missed by people making this modification. One boat that I worked on had an incident at the dock where a below waterline hose blew in the midships compartment. By the time the high water alarm had gone off, the water level in the engine room was increasing rapidly and half the engine was underwater. Luckily, the engine started and the large hydraulic trash pump lowered the level while the problem was traced down (this is a big boat so it takes a while to find it). Not only was the boat still in jeopardy of sinking, other than the high water alarm, the crew would not have known where in the boat to even start looking as there was water in all compartments. The reason that these bulkheads were not totally waterproof is that it was a wooden boat and it is incredibly difficult to make traditional bulkheads that are watertight. Even in non wooden boats, I have seen many owners get careless and start putting holes in the bulkheads that are not properly sealed (silicone sealant doesn’t count, you actually need a bulkhead fitting).

It is also worth noting that watertight doors have limitations. The obvious one is that they need to be closed to work (and it would be really hard to close one once there is water) but in most installations, a good crew will have no problem with this. The other limitation is that they are really sensitive to being adjusted right and not being bent. All doors should be chaulked regularly to ensure that they actually seal, as they get used a lot, they tend to stop sealing well. Also, I have some concerns about how some door designs would do if the bulkhead they were in was damaged. Steel and aluminum bulkheads will often bend a lot without being breached but these doors may not seal well at all. It is still much better than nothing and I have absolutely no problems with a well executed installation and disciplined crew, it just needs to be thought through.

All good points, and as you say, watertight bulkheads in wooden boats are hard to achieve. I used to skipper an old wooden boat that (supposedly) had watertight bulkheads, and they were anything but. And she finally sank when alongside a dock….

I agree that there is always the danger of leaks unless the doors and their seals are maintained, and also that an impact might distort or bend a bulkhead, one of the reasons I went for the compromise we have is that although it’s further forward than I’d like, there’s no need for a door.

Our boat is a 40 foot aluminium sailboat without a watertight bulkhead but a fairly large forepeak. The chain locker is unsealed plywood (came like that!), and is getting soft and stinky. I’ll need to do something but am unsure just what to do yet. Thanks for this overview, it’s given me some ideas!

I did have a couple of questions – did you need to replicate your bilge pumping arrangements for each water-tight section, or do you have a self-draining system? We do have a self-draining locker forward of the windlass that I’m trying to figure out a good use for – perhaps storage for long warps. Also, I’ve yet to see a satisfactory way of dealing with water ingress through the hawse-pipe – any ideas would be interesting in your upcoming post on keeping the water out!

Our compartments don’t have individual pumping arrangements – they are there to keep the water out of the main compartment of the boat, and rate not too massive in terms of capacity.

When you say self-draining, I’m assuming you’re talking about draining back to the sea? Like an anchor locker? There area number of ideas about such areas in Part II. Ditto – hawse pipes, which can indeed be a pain, but there are things that can be done to help.

I’ll mention emergency flotation bags for those of us with boats that don’t have watertight bulkheads.

Back in the ’80s I was involved in the development of the Float Pac system (now Turtlepac). One big dive bottle and 2 bags give almost 2000kg of flotation . They take up little space (often simply laid out under mattresses) and can be instantly deployed. Enough of them will keep you afloat and as Colin says “even if it only buys you time, those might be the most precious minutes of your life.” Better than jumping into a liferaft.

While ultimately not as tough as water-tight bulkheads they have another use that can be invaluable. They can be used externally (lashed under the hull/keel) to reduce draft when grounded and more than one boat has been floated off using them. Having a few dive bottles aboard may be useful as well.

good point, and something I’d completely forgotten about, so thanks for bringing it up. I suppose the only thing is a question of the scale necessary to keep a monohull afloat – I seem to recall they were being heavily promoted for multihulls at one time?

You’re right about scale, Colin, and yes, they were promoted as extra flotation for multihulls as well as a means of righting a capsized one though I haven’t heard of this actually being successful. Laszslo Torok of Turtlepac would have that information. I do know that they have prevented a number of ditched helicopters from sinking.

There are still quite a few smaller boats out cruising the oceans and inflatable emergency flotation for boats under about 35′ is really worth considering. Especially for timber or foam sandwich boats where the hull material already contributes to the flotation and/or if the ballast ratio is modest – as in some more traditional designs. A 1000 kg lift capacity bag weighs 6kg. An 80 cu ft dive tank is needed to inflate 2 of these bags and this weighs about 15kg. So, to provide 6 tonnes of lift you are looking at 6 bags @ 6kg each + 3 bottles @ 15Kg each. A total weight of 81kg ( ~180lbs). Quite a substantial weight but when you look at the ‘stuff’ aboard many cruising boats carry this would seem reasonable: especially if you then decide you don’t need a liferaft and enjoy diving.

I would much prefer to stay with my boat even if it was full of water: as long as it was floating. Far better to have all your provisions, tools and so on than to be drifting about in a liferaft. Exactly like watertight bulkheads – often repairs can be undertaken if one has the time. Another advantage over the liferaft option is that they can easily be maintained and checked (not that they need much maintenance).

I am fortunate in having a strongly built aluminium yacht and have the luxury of watertight bulkheads and a double skinned bottom (8 integral water tanks) but, as others have commented, this is not an easy option for many.

I’m straying slightly from the original topic here but as it is relevant will mention that Laszlo Torok of Turtlepac has also recently developed an interesting emergency hull bandage. A bit like the old technique of passing a sail under the hull and using water pressure to hold it in place to attempt to stop a leak this is a tough reinforced polyester reinforced PVC inflatable ‘blanket’. Once lashed in place it is inflated and so uses both bouyancy and water pressure to hold it securely in place and ensure a seal.

(I should mention that I have no financial interest in this business whatsoever having only ever worked with the company for a short time in the ’80s as a consultant.)

Interesting idea, and I’ll definitely take a look at it.

I do have some concerns about the practicality of such ‘bandages’ however, which I’ll be touching on in a later post in this series.

My 43′ GRP boat has great potential for long distance cruising, but the lack of a waterproof bulkhead is surely one limitation of the design. Very interested in the idea of an internal foam layer to help reduce the “openness” of a hull breach. Wondering if there are any downsides to this approach other than the loss of some storage space…..

The best example I’ve seen had reinforced the under bunk bulkhead in the forward cabin, and then glassed in a lid to cover it. An aperture had been left and structural foam blown in, which was then sealed off once the foam had cured. Looked neat, but as you identify, some space was lost.

That aside, it looked like a good, low cost solution, and as I mentioned in my post, I’ve heard of a couple of very supportive stories concerning boats that had been involved in collisions with floating objects.

For what it’s worth, Colin, I just found this video of an inflatable ‘collision mat’ being deployed.

http://www.youtube.com/watch?v=PJYBe2O3eqs

The Deportation of 1944 – How It Really Was? – Umalt Chadayev

February 23 this year marked the sixty-fourth anniversary of the mass deportation of Chechens and Ingush to Kazakhstan and Central Asia. In a matter of a few days almost half a million people, mostly women, children and the elderly, were loaded on to special trains and sent into the unknown.

To this day, in spite of two extremely brutal military campaigns which have recently claimed the lives of tens of thousands of civilians in the Chechen Republic, those who witnessed it at first hand remember “Stalin’s deportation” as one of the most terrible tragedies in their lives. Chechens consider that their thirteen long years of exile in the steppes of Kazakhstan and Central Asia caused a great many changes.

“Not only were the Chechens, like many other peoples of the North Caucasus, deported from their ancestral homeland – they were also subjected to a process that was intended to deprive them of their historical memory. I’m told that for several days after February 23, 1944, ancient Chechen manuscripts (teptary) were burned in Grozny. In the mountains, centuries-old historic towers were dynamited: in the Argun Gorge (southern Chechnya) alone, some 300 of them were destroyed. Our ancestral cemeteries were razed to the ground, and the gravestones (churty) were used for the construction of various buildings and roads,” says the Chechen State University professor Sharani Dzhambekov .

“February 23 is one of the most tragic dates in the history of the Chechen people. It will be remembered by our children and our children’s children because it affected every Chechen. More than half of our compatriots were left in unmarked graves on the way to Kazakhstan, Kyrgyzstan and Central Asia, and also when they got there,” he adds.

“About a month before the deportation Soviet soldiers came to the mountain villages. They said that the troops were getting ready for some sort of major exercises. But people were doubtful because there were already rumours that the Kalmyks and Karachays had been deported, ‘to Siberia ‘, as it was said at the time. But no one wanted to believe it, or that the same thing could be done to us,” says 78-year-old Grozny resident Salavdi Khadzhiyev . “At the time, we were living in the Vedensky district of the Chechen-Ingush Republic.”

“On the morning of February 23 all the adult men were called to some kind of meeting in the centre of the village. There they were surrounded by soldiers, and then a decree was read out to them. It said that the Chechens were being deported, and then they were ordered to immediately get their families ready for a journey. Soldiers went to each house and gave the families twenty minutes to make preparations. They were told to take warm clothes and food for three days, but no further explanation was given. I was just a teenager at the time, but I can still hear the crying and wailing of our women. It was horrible. No one knows exactly how many people died on the road of hunger and cold, or how many perished when they reached their destination. There were many thousands of such people.”

“Women, children, old folk, men from various families were herded into a single wagon. There were no toilets. The menfolk cut a hole in the corner and draped it with a blanket and a sheet. That was the toilet. But many people, especially young girls, were too embarrassed to use it, which damaged their urinary tract and even led to their death. In our wagon a 14-year-old girl died. There were also a lot of such cases in the other wagons. February 23 and the days that followed it were a road to nowhere – they were the most terrible shock of my life. Now, after the two wars that have been here, I realize that there are things worse and more terrible than the ones I experienced back then,” says 75-year-old Nepisat Akayeva , a female resident of the republic’s Itum-Kalinsky district.

“My father told me that when a trainload of Chechens arrived at one of the railway stations in the Aktyubinsk Oblast of Kazakhstan, they tried to find out where they had been taken. There were a lot of Kazakhs standing there. They’d been specially sent with horse-drawn sleighs to take the deportees to their places of accommodation. Well, one of the Chechens, who had previously worked as a teacher at a school, knew several languages and decided to talk to the Kazakhs. He began in Russian, but they were silent. He said a few words in Chechen, but they didn’t understand. He tried some other language as well, but again there was silence in response. Then he turned to his fellow countrymen and said: “We’ve probably been taken to Mongolia. They don’t know any language but their own,” another resident of Chechnya, 48-year-old Ayub Ishanov , relates.

“Of course, there were various different attitudes towards Chechens in those days. There was a lot of meanness and nastiness, but quite a lot of decency, too. For example, my grandfather who fought at the front in 1944, was forced to emigrate to Kazakhstan, as all frontline Chechen soldiers were. For several years he tried unsuccessfully to find out what had happened to his brothers and sisters, of whom before 1944 he’d had nine. In the end it became clear that only one sister had survived. She was living with her two small sons on a collective farm somewhere near Alma-Aty. And my grandfather was living in the Gurevsky district [of Western Kazakhstan] at that time,” 30-year-old Chechen resident Shamkhan told Prague Watchdog’s correspondent.

“He decided to go there and bring his sister and nephews back with him. He also learned that his sister was seriously ill with typhoid. At his own risk he went to Alma-Aty, hiding on the roofs of rail cars – at that time Chechens were forbidden to leave their places of settlement, a crime for which they could be sent to a labour camp for 15-25 years. Somewhere near Alma-Aty he was arrested and taken to the local commandant’s office. On learning that my grandfather was a Chechen, had fought in the Second World War and was going to fetch his sister, the commandant, a Ukrainian by nationality and himself a frontline officer, let him go. Moreover, he gave him some sort of pass which provided him with immunity from arrest. My grandfather always remembered that man with gratitude. He found my sister and his nephews, and took them home.”

“And in one of the other districts of Kazakhstan, I don’t remember now exactly where this happened, there was another commandant who was in charge of the ‘special contingent’. He would even let Chechens leave the auls [villages] where they lived. There were two villages next to each other, separated by a small river. Several dozen Chechen families lived in one of them. But the only cemetery was on the outskirts of the other aul, where only Kazakhs lived. When a Chechen died, the commandant would not allow the family to cross the river to bury the body in the cemetery. Chechens had to carry the deceased person on a stretcher to the middle of the river, and the Kazakhs would come out from the other side. They’d take away the corpse and bury it in their cemetery. Those are the sort of ‘customs’ there were then.”

“Though it has to be said that the things that happened during the deportation were as nothing compared to what happened here during the two recent military campaigns. In those days there were no mass bombings of villages, no large-scale abductions, there was no brutal torture of detainees, no selling of corpses and killing of hostages. Though in my opinion both the 1944 deportation and the two military campaigns (the 94-96 military actions and the ‘counter-terrorist operation that began in 1999) were acts of genocide,” Shamkhan is convinced.

Just 64 years ago, on February 23, the mass deportation of Chechens and Ingush to other regions of the Soviet Union, primarily Kazakhstan and Kyrgyzstan, began on the orders of the Kremlin leadership. The large-scale operation, codenamed “ Chechevitsa ” [ Lentil ], was personally supervised by People’s Commissar Lavrenty Beria . Archive data from the Chechen-Ingush Autonomous Soviet Socialist Republic (ChI ASSR) indicates that 478,479 people were deported, including 387,229 Chechens and 91,250 Ingush. According to various sources, in the early years of their exile about half of the Chechens and Ingush died from hunger, cold and disease.

In 2004 the European Parliament recognized the 1944 deportation of the Chechens as an act of genocide . The Kremlin leadership has so far taken no real steps aimed at the rehabilitation of these repressed peoples, despite the fact that in November 1989 a law to that effect was passed in the USSR. In “compensation” for their forced exile, Chechens (as victims of deportation, and their children born before 1957 – the first year in which Chechens were allowed to return to their historic motherland) are being offered payments of 10,000 roubles (about $400) per family. In Chechnya this is viewed as just more mockery of the Chechen people’s memory, and the vast majority of Chechens do not plan to take these miserable sums from the government.

Umalt Chadayev Prague Watchdog – 2008

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January 24, 2000 Troops in Grozny Measure Their Gains in Yards By MICHAEL R. GORDON HANKALA, Russia, Jan. 23 -- Today's flag-raising ceremony in northwest Grozny was supposed to be a made-for-television event that would illustrate the progress Russian forces have made in taking back the tattered ruins that are the Chechen capital. But when a group of reporters and photographers arrived at the outskirts of the city, they were abruptly turned away. Even the Russian-occupied areas of Grozny were filled with rebel snipers, a military press officer explained. The New York Times on the Web RUSSIA'S OFFENSIVE IN CHECHNYA Recent Coverage Leader of Troops in Chechnya Is Replaced (Jan. 23) Week in Review: Grozny to Moscow: Fear Blazes a Path (Jan. 23) Putin Warns Russians of Terrorism by Chechens (Jan. 22) A Top General in Chechnya Is Missing After Battle (Jan. 21) Many Russians Questioning Official Toll in Chechnya (Jan. 21) Russian Aim: Wind Up War in Chechnya Before Election (Jan. 20) In a Fierce Assault, Russian Soldiers Advance Into Grozny (Jan. 19) Russians Pummel Grozny From Air and With Artillery (Jan. 18) In Chechnya, an Undaunted Diplomat (Jan. 17) Russia Takes Chechen Town, but Can the Troops Keep It? (Jan. 14) U.S. Puts a Low Profile on Meeting With Chechen Foreign Minister (Jan. 14) Russia Offers Clues Linking Chechens to Apartment Bombings (Jan. 13) Troops Try to Regain Footing in Chechnya After Rebel Strikes (Jan. 11) Russian Troops in Chechnya Find Little Quiet on the Southern Front (Jan. 10) From the Archives Complete Coverage of the Conflict in Chechnya from June 1999 - Present Video Chechnya Under Fire Slide Shows Chechens Say They Were Shot At in Safe Corridor (Dec. 17) As Russia Assaults Grozny, Chechen Refugees Trickle Out (Dec. 17) Russians Advance Rapidly to Outskirts of Grozny (Dec. 1) At a Glance Key Players in the Chechen Conflict Key Facts About Chechnya Issue in Depth Russia's Turmoil Map Chechnya Forum Join a Discussion on Russia's Turmoil Related Web Sites Russian Government Internet Network Chechen Republic Online Official Website of the Chechen Islamic Rebels (in Russian) When Russian forces began their latest assault on Grozny early last week, they boasted that they would make short work of the militants in the city. But the Russian blitz has begun to stall. Russian gains are measured in yards. The Russian military's most important accomplishment today was not the seizure of a new building or compound, but the recovery of the body of Maj. Gen. Mikhail Malofeyev, one of the commanders of the Grozny operation, who vanished in the fighting on Tuesday. Another commander, of the Interior Ministry troops who have been doing the main fighting in the streets of Grozny, has been replaced. Senior Russian officers have voiced fears that they have become mired into a war of attrition. "Many units which I know in the defense and interior forces are exhausted," Lt. Gen. Arkady Baskayev, a senior Interior Ministry commander in the Moscow region, told a Russian radio station today. "They must be supported by new forces, by new equipment, by new arms." Lying on the eastern outskirts of Grozny, Khankala is a major base for the Russian assault on Grozny. It is an unsightly panorama of rusty railroad cars, a military airstrip and makeshift command posts, erected out of concrete piles and camouflage nets. Russian artillery here send 122-millimeter shells flying toward the city, and attack helicopters hover overhead. The Staropromyslovsky district of Grozny is just a short helicopter ride away. The district extends like a finger toward the northwest. It was the first Grozny district the Russians attacked when they began their assault on Grozny on Dec. 25, and they claim to have had it under control since late December. Russian forces even established a local militia office there in the beginning of January, as they sought to bring the situation back to normal. The decision to raise Russia's tricolor in Staropromyslovsky was intended as a symbolic affirmation of Russian progress. It came after a difficult week for the Russian side. First, General Malofeyev disappeared, with the rebels declaring that he had been kidnapped. But today, Lt. Gen. Gennadi Troshev, the deputy commander of Russian forces in the North Caucasus, said that the general's body had been recovered in a no-man's land and that Russian artillery had been used to prevent the rebels from seizing it. Territory that the Russians had previously claimed to seize has also become the scene of bitter fighting. Russian officers boasted that they controlled Minutka Square in central Grozny several days ago, only to acknowledge today that it was still the object of fierce firefights. Compounding the Russian military's problems, the rebels staged a surprise counterattack on soldiers in the Staraya Sunzha area, just north of the city. And Chechen paramilitary units allied with Moscow have suffered heavy casualties. On another front, fighting rages in the Chechen highlands as rebels in the Argun gorge try to fight their way back to Grozny. Even celebrating the capture of Staropromyslovsky was not easy. The Russians took extensive precautions for today's flag-raising ceremony there. Russian snipers took up positions on nearby rooftops to fend off any rebel attacks. The district itself has been heavily scarred by the fighting. Its buildings have been blasted by artillery fire, one of the Russian military's main means for dealing with rebel snipers. That has turned many of the structures into charred, windowless hulks. Many of its residents, however, have refused to leave. And today a small rally was organized for some of the civilians who have endured the battle for the city. A few television correspondents were brought to the district in the morning and documented the event. But after the Russian military brought a group of reporters, television cameramen and photographers here later in the day, they were informed that snipers were active in the Russian-controlled area of Grozny and that travel to Staropromyslovsky had become too risky. Asked when it might be safe to return, they were told in four or five days. Given the political stakes involved for Acting President Vladimir V. Putin and the firepower Russia has at its disposal, it seems virtually certain that Russian forces will eventually retake the city. The question is at what cost to the troops, to the Kremlin's prestige and to the thousands of civilians who live in the capital. Although Russian generals have said their goal is to win the war before the March 26 presidential elections, Mr. Putin said in an interview broadcast on RTR television tonight that the end of the war in Chechnya "will not be linked to any date in the political calendar in Russia." Mr. Putin said the war would be over with "the total liquidation of the groups of bandits," the deployment of a permanent security contigent in place of federal forces and the start of a "democratic process" in Chechnya. Apparently seeking to regain the initiative this weekend, Mr. Putin replaced the head of the Interior Ministry troops, Vyacheslav Ovchinnikov, with Vyacheslav Tikhomirov, who led Russian troops in Chechnya during the final year of the 1994-96 war, which ended in de facto independence for Chechnya. General Tikhomirov was known for his hard-nosed attitude toward the Chechens. A Russian military report today sought to paint an upbeat picture of the fighting. It insisted that the rebels' morale was plunging and added that the Russian forces were in the process of "mopping up" the Russian-controlled areas of Grozny. But General Baskayev, the Interior Ministry officer, had a more caustic assessment. "There can be no 'mopping up,' because that term implies that we are already in control of the situation," he said.

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Maryland Fishing Report – August 28

Hopefully, all our crabbers are as lucky as John Turrall and catch a mess of jumbo hard crabs that are large and full of meat. Photo by Rich Watts

Forecast Summary: August 28 – September 3

Cooling weather with limited rain predicted will make for comfortable fishing conditions this week in Maryland’s waters. As a result of the recent warm spell, main Bay surface water temperatures have warmed to the low 80s. Maryland’s part of the Bay continues to run fresher than average. Larger areas with suitable amounts of oxygen – greater than 3mg/l – have continued to be available again this week. For finding the best combination of well oxygenated, cooler water preferred by many Bay gamefish, focus on fishing deeper during the daylight hours.   

Expect average water clarity for most of the Maryland portion of the Bay. However, expect reduced but improving water clarity in the lower Susquehanna River and upper bay from recent rains. In addition, expect reduced water clarity in the Bush, Back, Rhode and West Rivers due to algal blooms. To see the latest water clarity conditions on NOAA satellite maps, check Eyes on the Bay Satellite Maps .  

E xpect average flows for the Susquehanna River and some other Maryland rivers and streams. There will be above average tidal currents Thursday through Tuesday as a result of the new moon on September 3.

As always, the best fishing areas could be further refined by intersecting them with underwater points, hard bottom, drop-offs, and large schools of baitfish.  For more detailed and up-to-date fishing conditions in your area of the bay, be sure to check out Eyes on the Bay’s Click Before You Cast.

Blue catfish, photo courtesy of Mark Hanson

The water releases from the Conowingo Dam have returned to normal flows following the previous heavy rains from Tropical Storm Debby. The water releases are now on more of an evening power generation schedule. Water clarity has improved in the immediate area but some spots in the upper bay region may still see cloudy water conditions. Water temperatures had dropped to below 80 degrees for the first time this summer, down to 77 degrees at the Patapsco NOAA buoy, but the temperature recently rose back up to about 80 degrees. Temperature should fall again after the current warmer weather passes. 

Anglers fishing in the Conowingo Dam pool, the lower Susquehanna River, and the waters near the Susquehanna Flats are catching a mix of largemouth bass, Chesapeake Channa (northern snakeheads) and a mix of blue and channel catfish. The largemouth bass can be caught in the river and the edges and in the grass on the flats, and the Chesapeake Channa are usually entrenched in the thick grass. There has not been much reporting of good fishing for striped bass in the general area. 

Fishing for a mix of blue and channel catfish is very good at the mouth of the Susquehanna and nearby tidal rivers this week. The catfish can be found along channel edges and fishing with cut bait is the most popular way to fish for them, although anglers often report them chasing down crankbaits.

Fishing for striped bass has been very good in the Pooles Island area, the mouth of the Patapsco River, and Baltimore Harbor. Live-lining spot is a very popular way to fish along channel edges, and cut bait can also work. Unfortunately, floaters in the form of striped bass measuring over the 24-inch slot maximum have been too numerous lately; hopefully with cooler water temperatures and better catch-and-release tactics by anglers, we’ll see less of this. 

Striped bass anglers are also having good luck casting soft plastic jigs and paddletails in the Baltimore Harbor area near bridge piers, shoreline rocks, and old pilings. The early morning and late evening hours offer the best fishing opportunities. 

Casting small spinnerbaits, soft plastic jigs, and spin jigs during the early morning and late evening is a great way to fish for large white perch that can often be found near promising shoreline structure. Some anglers up their game by placing a little piece of peeler crab on the hook of a jig or spin jig. The tidal river shorelines of the upper Bay offer many places to explore.

Craig Roberts holds up a pretty pair, a slot size striped bass and red drum, both caught while live-lining spot. Photo courtesy of Craig Roberts

Now that water temperatures in the middle Bay have fallen to the upper 70s, fish are responding in a big way in the shallower waters. Casting a mix of paddletails, spinnerbaits, topwater lures, and soft plastic jigs in the shallower waters is still best during the early morning and evening, but fishing success has greatly improved from a few weeks ago. Puppy drum, striped bass, and speckled trout can be found in a wide range of locations. Eastern Bay, Poplar Island, the Choptank, Little Choptank and South River are just a few spots where anglers are having good success. More than a few anglers are also learning that spin jigs can be a great asset when fishing for striped bass, puppy drum, and large white perch. 

Bluefish are in the middle Bay and anglers getting most of the action are trolling Drone spoons and surgical tube lures behind planers. The channel edge from Buoy 83 south to the Diamonds has been a good place to troll. A few Spanish mackerel are also being reported in the mix with faster trolling speeds. 

Live-lining spot is another option this week at Thomas Point, the Clay Banks and the Calvert Cliffs Power Plant Discharge to name a few. Live spot will work well for striped bass, slot size red drum, and large speckled trout. 

Fishing for white perch is an excellent choice for fishing this week; the white perch are getting heavy shoulders and there seems to be quite a few large ones around. Casting small spinnerbaits, spinners and small soft plastic jigs is a fun way to fish for them along promising looking shoreline during the early morning and evening hours. Placing a piece of peeler crab on a jig can help entice the perch’s appetite further. 

Bottom fishing with grass shrimp or peeler crab around old docks and piers is a favorite summer pastime. Fishing over oyster reefs in the tidal rivers is another option. The west side of the Bay Bridge in about 15’ of water and the Kent Narrows are two great places to fish. When fishing with pieces of bloodworms at the Bay Bridge or tidal river locations spot can be part of the mix. 

Anglers can register now for the  Rod and Reef Slam , a tournament that focuses on restoring oyster reefs throughout the Chesapeake Bay and its tributaries. This annual event, sponsored by the Chesapeake Bay Foundation and the Coastal Conservation Association, starts at 6 a.m. on September 7 and runs through 11 a.m. on September 15. The grand prize is awarded for most species caught and includes powerboat, kayak, youth, and invasive species divisions. Registration, which includes food and drinks, is available on the  Chesapeake Bay Foundation website .

Bluefish, photo by Travis Long

In the lower Bay, anglers are enjoying excellent catches of Spanish mackerel and bluefish while trolling. Higher trolling speeds of 7 or 8 knots with small Drone or Clark spoons behind planers has been the best way to fish for the Spanish mackerel. The main channel edges in the Bay, the mouth of the Potomac River, and Tangier Sound have been excellent places to fish for them. Anglers may be lucky enough to come upon breaking fish of Spanish mackerel and bluefish. Casting metal jigs into the fray, allowing the jig to sink, and then speed reeling can be a fun way to catch Spanish mackerel. 

Trolling small Drone spoons and medium-sized surgical tubing lures at slower speeds is a great way to fish for bluefish. A few anglers have also reported catching cobia and large red drum on the surgical tube lures. Casting into breaking bluefish with a moderate retrieve is another fun way to catch bluefish. Some anglers are setting up chum slicks focused on bluefish or cobia and catching bluefish on cut bait and a few cobia on live eels or cut bait.

Once again, the shallow water fishery for puppy drum, striped bass, and speckled trout is good this week in many locations. The lower Potomac and tributaries that feed into it are providing fun light-tackle fishing. The Hoopers Island area along with Tangier and Pocomoke sounds are also great places to fish. A mix of topwater lures, paddletails, soft plastic jigs, and spin jigs provide popular choices for casting. Other anglers are enjoying excellent fishing by drifting peeler crab baits in areas of strong tidal current movement. Peeler crab baits are also popular when fishing near the Target Ship for sheepshead. 

Bottom fishing for a mix of spot, croaker, kingfish, and a few small black sea bass has been very good this week. The mouth of the Patuxent River and Tangier Sound are two excellent places to fish for spot and croaker. The spot are becoming about as large as they can be before heading south in October, and anglers are catching croaker above the 9-inch minimum. The kingfish join in with the mix at times and the black sea bass are being caught near artificial reef structure. Flounder can be caught near Point Lookout, Tangier Sound and Pocomoke Sound for those targeting them along channel edge shelfs. 

Fishing for blue catfish in the tidal Potomac, the Patuxent and Nanticoke rivers is very good this week, with plenty of good eating catfish available. They can be a fun fishing opportunity whether fishing from a boat or from shore. A fish finder rig tied into a circle hook with cut menhaden or chicken liver for bait will get you in on the action. If fishing from shore with soft chicken liver, a hefty cast may see the chicken liver going in one direction and your sinker in another. Try brining a batch of chicken livers in non-iodized salt to firm them up. 

Recreational Crabbing

Recreational crabbers are enjoying good catches in most areas of the Bay. Upper Bay crabbers are doing well in the region’s tidal rivers. In the middle Bay, excellent places to catch crabs include Kent Island and the Wye, Miles, Choptank, and Little Choptank rivers. Recreational crabbers report good crabbing in the Rhode and South rivers. Water depths between 12 feet and 15 feet tend to be the best for catching larger crabs. 

There are some new crabbing regulations just issued regarding the legal limit or recreational crabbers. This allows recreational crabbers to use other containers for their crabs if they can keep count. The wooden bushel baskets are becoming scarcer, so this will be a big help, but remember to get an accurate count on those crabs – six dozen is the legal limit for recreational crabbers. 

Trevor Cockran caught and released this fine-looking largemouth bass at Piney Run Lake recently. Photo by Amanda Cockran

The fishing at Deep Creek Lake continues to follow a typical summer pattern, with anglers fishing for largemouth and smallmouth bass early in the morning and late in the evening. Main lake points and grass lines are good places to look with top water lures and spinnerbaits. Tubes and plastics in pumpkin or watermelon colors, cast under docks, moored boats, fallen treetops and stumps are good places to check during the day. Fishermen are reporting that the boat traffic is starting to slack off as the summer vacation season begins to wind down. There’s a lot better fishing ahead for sure.

This is often the time of the year for ant swarms, and fly anglers should keep watch on their favorite trout streams, rivers, and even ponds and larger bodies of water. Trout will be feasting on the ant swarms as hapless flying ants fall onto the surface of the water. The popular ant patterns can range from as small as No. 22 to as large as a No. 16. Sunfish will also get in on the action at ponds and lakes. 

The upper Potomac has calmed down and water temperatures have fallen, and water clarity is good. Casting root beer-colored tubers and crankbaits mimicking crayfish are good lures to cast near mid-current boulders, submerged ledges and current breaks. Cooler water temperatures in September should increase smallmouth bass activity. 

Largemouth bass are still holding to a typical summer pattern of feeding behavior, but water temperatures are beginning to show signs of cooling. The cooling of waters whether it is in a pond, reservoir or tidal river will have the same effect on the largemouth bass wherever they reside. They will start to feed more aggressively later in the mornings and earlier in the evenings. 

When the largemouth bass are actively feeding in the shallow waters where grass is thick, frogs, buzzbaits, and wacky rigged worms are hard to beat. In the tidal rivers, Chesapeake Channa will also challenge noisy topwater lures with explosive strikes. As the morning wears on and the sun is high in the sky, largemouth bass will look for cool shade in the form of floating grass mats, fallen treetops and brush, old docks and moored boats, and deep sunken wood. Wacky rigged worms tend to be the lure of choice in these circumstances.

The persistent south winds and churned-up surf are now just a memory, and anglers are enjoying catching a mix of kingfish, spot, blowfish, and flounder in the surf. The kingfish are being caught on pieces of bloodworm and small strips of spot. The spot want bloodworms or artificial bloodworm baits, and the blowfish and flounder are being caught on strips of squid.

At the Ocean City Inlet and Route 50 bridge area, bluefish and striped bass are entertaining anglers who are casting soft plastic jigs during the morning and evening hours. Flounder are always moving through the inlet, and drifting live spot or other small baitfish and Gulp baits will entice the larger flounder. Sheepshead are being caught here and there at the South Jetty and inlet bulkheads on sand fleas. 

The back bay channels continue to be the place to fish for flounder this week. The Thorofare, East Channel, and in front of the Ocean City Airport will always be good places to drift for flounder. Traditional baits of squid and minnows are standard and small flounder, black sea bass, and sea robins will keep you busy if you’re fishing near the inlet. Many anglers live-line spot and similar sized live fish or use Gulp baits to target the larger flounder. 

Outside the inlet the wreck and reef sites are usually providing good fishing for black sea bass, with small dolphin and flounder often thrown into the mix. At times anglers are frustrated when the black sea bass refuse to bite and often must move to another fishing site to get some action.

Farther offshore, there are plenty of small dolphin to be found at the lobster pot buoys. The anglers who are trolling the canyons are finding a mix of bigeye tuna, yellowfin tuna and white marlin this week.

“There are two distinct kinds of visits to tackle shops, the visit to buy tackle and the visit which may be described as Platonic when, being for some reason unable to fish, we look for an excuse to go in and waste a tackle dealer’s time.” – Arthur Ransome, 1929

Maryland Fishing Report is written and compiled by Keith Lockwood, fisheries biologist with the Maryland Department of Natural Resources . 

Click Before You Cast is written by Tidewater Ecosystem Assessment Director Tom Parham.

A reminder to all Maryland anglers, please participate in DNR’s Volunteer Angler Surveys . This allows citizen scientists to contribute valuable data to the monitoring and management of several important fish species.

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