yachting apparent wind

Apparent wind

by Niclas | Oct 21, 2015 | sailing basics , tactics | 1 comment

Understanding how Apparent Wind works and its impact on how you should efficiently sail the boat is crucial, and even though it may seem theoretical at first it’s well worth mastering this subject. You may get some “aha moments” while reading the theory as you would have seen the effects on the water already.

What is Apparent Wind?

The wind you experience while moving with the boat is called Apparent Wind . It’s the combination of the True Wind and the  Boat speed Wind .

Apparent wind changes in wind gusts

So, what happens when your boat sailing close hauled suddenly is hit by a stronger breeze – a wind gust?

The first thing that happens is that the True Wind component increases, and hence the Apparent Wind  also increases and changes direction. This means that your leeward telltales will suddenly start spinning, the boat will be heeling over from the stronger wind and it feels like you are getting a lift, although the True Wind still comes from the same direction as before.

When the boat is hit be the more powerful breeze it will either accelerate and eventually the True Wind direction will become more or less the same as it was before the gust, or if the boat has already reached its maximum speed it won’t accelerate further. Hence the way to respond to these gusts will vary if you’re in e.g. a small planing skiff or in a large keel boat.

and in lulls…

The opposite obviously applies when sailing into a lull (less wind). Suddenly the Apparent Wind changes direction and your windward telltales will start spinning around. It’s tempting to bear away, although if it’s a very short lull it may be better to keep your course waiting for the wind to fill in again. There may also be a temptation to tack as it feels like you’ve been headed. The decision whether to tack or not should then be based on where the best wind strength is and other tactical aspects such as what other boats are doing. Just be aware it’s not a real header you sailed into.

The boat will also slow down in the lighter breeze and eventually the Apparent Wind direction will be similar to before. Again, changes in boat types will react differently, where a large heavy boat will keep its boat speed much longer than a dinghy would.

Why fast boats don’t sail dead downwind

Let’s now look what happens when we sail downwind. See how the Boat Speed Wind   and the True Wind are opposite resulting in a small force of Apparent Wind speed. At times at the end of a gust, or surfing down a wave, you may even sail faster than the wind and suddenly all power goes out of the sails.

For fast planing boats going dead downwind is rarely a good option as they will be so much faster reaching that the extra distance they will need to cover is more than well compensated for in better boat speed. By sailing at more of a reaching angle these boats will generate more apparent wind which in turn allows them to sail much faster.

Apparent Wind and current / tide

If you’re sailing in a current your boat speed component will also be affected by the moving water. We’ll look further into this in another article.

I’m sure there’s a lot more to be said about apparent wind, but this hopefully should serve as an introduction. As always we welcome questions and comments to the article.

Share this:

I have a 12 ft non planing dinghy. Does it make sense to reach on a downwind? Thanks!

Blogroll - Sailing blogs

• Americas Cup info site
• Sailing World Magazine

Rules and regulations

• RORC, including the IRC handicap rule
• The rules of racing

Sailing organisations

• Americas Cup
• Australian Olympic sailing team
• International Canoe Sailing Organisation
• International Sailing Federation
• Yachting Australia

tips and tricks

• Sailing world experts section
• boat handling
• sailing basics
• Sydney sailing

Yachting Monthly

• Digital edition

Apparent wind: How to predict it and use it to your advantage

• Katy Stickland
• July 1, 2022

Predicting changes in apparent wind will make you a safer, faster sailor, says Martin Watts

Knowing what to do when the apparent wind changes could be the difference between accelerating smoothly and broaching badly. Credit: Graham Snook/Yachting Monthly

Newcomers to sailing soon learn to appreciate the differences in apparent wind on different points of sailing, writes Martin Watts.

We’ve all slogged to windward in a Force 5, clad head to toe in waterproofs as spray flies over the deck, only to see a boat sailing in the opposite direction, downwind , with the crew lounging around in shorts and T-shirts enjoying what looks more like a Force 3.

However, the apparent wind can also change whilst sailing on a leg of a route, and understanding these changes and how to respond to them can improve not only speed, but also the efficiency of how a yacht is handled, comfort on passage as well as safety by avoiding losing control in broaches and other incidents.

Changes in true wind direction are obvious, but there are other reasons for apparent wind changes.

As wind increases in gusts, the apparent wind angle will move aft. Credit: Maxine Heath

I’ll start by looking at what causes these changes and then how we respond to them.

If the true wind speed suddenly increases in a gust, then not only is there an increase in apparent wind speed, but the apparent wind angle (AWA) changes in direction, moving further aft with respect to the yacht.

Conversely, if there is a decrease in the true wind speed, then the apparent wind speed decreases, but it now moves further forward in relation to your boat.

There are also changes in the apparent wind due to variations in the speed of the yacht.

If the yacht’s speed drops, then the apparent wind decreases and moves further aft.

If the boat slows down, the apparent wind will also move aft, while an increase in boat speed will bring it forward. Credit: Maxine Heath

If the yacht speed increases, then the apparent wind speed increases and the apparent wind angle decreases, moving further forward.

This effect can clearly be seen on the foiling catamarans who have their sails sheeted in all the time.

In practice, any change in apparent wind speed and angle are usually a combination of both of these mechanisms.

The common sight is a strong gust hitting a yacht.

Continues below…

Why twin headsails are best downwind

Crossing the Atlantic from Cape Verde to Barbados took us just 13 days in our 1998 Lagoon 410, Cushla Na…

Sail trim in light airs: 7 tips to keep you sailing

John Parker, owner of the OneSails GBR (East) loft shares his top tips on sail trim to make the most…

Sailing in waves: top tips to keep you safe at speed

Sailing in waves can make for a jarring, juddering experience and long, uncomfortable passages and at worst, a dangerous, boat-rolling…

How to cope with gusts and squalls

Spikes in wind strength can range from a blustery sail to survival conditions. Dag Pike explains how to predict which…

The extra power and the fact that apparent wind is now more beam-on to the yacht means the sails are over-sheeted and there are large lateral forces that make the yacht heel, which result in a less efficient hull shape requiring more rudder to be used to keep the yacht going straight.

This all slows the boat down, and so the apparent wind shifts even more beam-on. The rudder eventually loses grip, and we end up with a broach.

So how should you respond to these changes in the apparent wind speed and direction?

The actual response will vary on the yacht, the crew and the conditions, and on whether you lean more towards the ‘racer’ or ‘cruiser’ ends of the spectrum.

Apparent wind: dealing with gusts

Gusts are formed in a variety of ways, but in open water, a gust is likely to have been formed by a downdraught around a cumulus cloud after a cold front.

If this is the case, the wind direction of the gust may be the same as the higher-level wind direction.

In the northern hemisphere, this will typically be veered compared to the sea-level wind.

‘Cats paws’ on the water show how gusts fan out as they hit the surface. Credit: Martin Watts

The result is that if you are sailing on starboard tack, you may get a lift to windward, while on port tack you would be headed.

It’s slightly more complex than this, however, as downdraught gusts fan out as they hit the water and so it helps to identify where the yacht is in relation to the gust fan so that the change in wind direction can be predicted.

If you are sailing towards the centre of the gust, on either tack, you are likely to be headed, while sailing away from the centre, you are likely to get a lift.

If you are hit by a gust when sailing upwind, the increase in true wind speed will move the apparent wind aft, giving you a lift in which you can luff up slightly, or if you are on course and don’t need to make more progress to windward, you can ease the sails to gain more boat speed and avoid excess heel, or do a combination of both.

If you are less concerned about performance, it is easier to just luff up slightly, which makes use of the lift, and also spills some power from the sails.

When a gust hits, its leading edge will often bring the strongest wind, so in blustery conditions, it pays to be looking upwind spotting approaching gusts, even if you’re just cruising.

Upwind, it pays to be prepared and not caught off guard by a gust. Credit: Graham Snook/Yachting Monthly

This gives you a chance to luff up significantly before the gust hits, so that the sails are lifting slightly and the yacht is not overpowered as the gust hits.

You can then slowly bear away again, keeping the boat under control and maintaining good boat speed.

As boat speed increases again and the apparent wind moves forward, both groups may end up sailing at a slightly lower heading than before.

In contrast, if you aren’t ready for the gust, you will heel and increase rudder angle, slowing the boat down, and if you then luff up, you will do so into the lighter wind behind the gust, further losing speed.

When sailing on a reach, easing the sails and bearing off slightly, so that the direction of effort is more in line with your heading, will give the biggest increase in speed.

Racers steer to keep the boat ‘under the sails’, reducing heel to keep the rudder gripping particularly when fully powered up.

They may even bear off more to stay in the gust, particularly in light winds, knowing that they will be coming back up to the original course line with a better apparent wind direction.

When reaching steer to keep the boat under the sails, bearing away in gusts. Credit: Graham Snook/Yachting Monthly

For a cruising sailor, the response to a gust when reaching can be rather different to this and is more similar to how they responded when sailing upwind.

Luff up slightly, or a lot before the gust hits if the gust is large to spill power from the sails, and then bear away as the gust eases.

Then as boat speed increases and apparent wind comes forward again, racers will sheet in, while cruisers may be content to bear away slightly to keep the sails full.

Things change again when running deep downwind.

With the wind astern and the sails sheeted right out, they are being pushed along, but there is no aerodynamic flow along the sails and they are not generating any lift.

The force on the sails is in the same direction as the boat’s heading, so there is no heel.

Rounding up towards the wind, far from depowering the sails, will do several things at once: it allows an airflow to develop and with it a significant increase in power; the apparent wind will increase as you are no longer running before the wind; and a large heeling moment, which could easily lead to a broach.

On a run, don’t be tempted to luff up to depower the sails; it will have the opposite effect. Credit: Graham Snook/Yachting Monthly

This is all exacerbated by the fact that there is a temptation to set more sail when downwind when things feel calm, only to find that you are hugely over canvassed as soon as you turn towards the wind.

So generally, the response is to stay heading in the same direction, with a key aim now being to stop the yacht burying its nose in the back of wave.

If you need to reduce power, sheeting in is a more responsive technique, or alternatively you could try reefing down to match your sailplan to the gusts.

Slowing down

When the true wind speed drops, when going upwind, the apparent wind moves forward and so the initial impression is that you have been headed.

The automatic reaction is to bear off, but you must do this gradually so that the yacht does not lose momentum as a result of large rudder movements and disrupting the airflow over the sails.

When the true wind speed drops on a reach, the apparent wind also comes forward, so you’ll need to sheet in or bear away to keep the sails pulling.

Wake from other boats will cause you to slow down and the apparent wind to move aft. Credit: Graham Snook/Yachting Monthly

One of the common reasons boat speed suddenly drops is because of wake from powered vessels.

The first response is to try and minimise the effect of the wave by steering accordingly.

As the yacht’s speed drops and apparent wind moves aft, ease the sails or luff up so that the apparent wind angle is the same as before the wake hits, so that the sails remain set correctly.

Heavy displacement craft like tug boats create particularly short and sharp ‘boat stopper’ wakes. Credit: Alamy Stock Photo

Then as the yacht’s speed increases, bear away back on to the original course.

In light winds, it may pay to keep sailing a bit higher, with more apparent windflow over the sails, to build up boatspeed more quickly before bearing away.

Waves and tide

The effect of yacht speed on the apparent wind direction is clear when sailing upwind with the waves or swell coming downwind.

As the yacht climbs the front of the wave, it slows and so the apparent wind moves aft, so the helm can luff up slightly to keep the sail trim right and this can help the boat punch through the top of the wave.

As the yacht goes down the other side of the wave, it accelerates and so the apparent wind moves forward and so the helm must bear away to keep the sails drawing properly.

Apparent wind can also be dramatically affected by changes in the tidal stream. Sailing with the tide will increase speed over the ground and with it, apparent wind.

As wave size increase, actively helming over each wave will keep the boat moving much better. Credit: Richard Langdon/Ocean Images

In terms of direction, the wind angle will move forwards, so sheeting in or bearing away will be necessary.

The more marked impact is that sailing upwind with the tide, the wind speed can increase dramatically, while on a run the apparent wind may drop a Force or two by comparison.

Things get more interesting when sailing across the stream.

With the tide on your leeward side, you would be favourably pushed towards the wind, ‘lee-bow effect’, while with tide on your windward side both apparent wind speed and progress to windward would be reduced.

Traditionally, the mark of a good helmsperson was that they could sail a course with a steady compass bearing, so that the navigator could make good dead reckoning calculations.

Martin Watts and his wife, Irene, have chartered in the Med and Caribbean. They own a Hanse 341 and sail from Largs, Scotland

Now with GPS and chartplotters , the yacht’s position is known, and the helm and crew have a greater flexibility to respond to apparent wind changes to maximise boat speed.

So, the yacht can be pointed on its desired course, the sails set accordingly and then the helm left to look around to predict the wind and wave conditions and steer to what feels right for the yacht and the conditions.

The aim is to be able to predict and react to any apparent wind changes, rather than just respond after the event.

Then, after a period of time, compare the actual and desired position or look at the cross track error (XTE) and alter the course heading and adjust the sails to suit.

Enjoyed reading Apparent wind: How to predict it and use it to your advantage?

A subscription to Yachting Monthly magazine costs around 40% less than the cover price .

Print and digital editions are available through Magazines Direct – where you can also find the latest deals .

YM is packed with information to help you get the most from your time on the water.

• Take your seamanship to the next level with tips, advice and skills from our experts
• Impartial in-depth reviews of the latest yachts and equipment
• Cruising guides to help you reach those dream destinations

Follow us on Facebook , Twitter and Instagram.

Understanding Apparent Wind: Visual Resources

It’s easy enough to explain apparent wind at a basic level, but once you start drawing vector diagrams, some sailors lose interest. The best explanations combine real-world experiences with simple diagrams and animations.  

In this article, we collected some of the best visual resources to explain apparent wind and the effects of:

Points of sail

Puffs and lulls.

• High performance boats, such as skiffs and foiling boats

Definitions

Everyone has their favorite terms for explaining apparent wind. The resources below use a combination of the following terms.

• True wind or ambient wind: the wind you feel when you’re not moving.
• Boat wind or head wind: the wind you feel strictly due to the motion of the boat.
• Apparent wind: the combination of true wind and head wind.

This short STEM video from U.S. Sailing uses an anemometer on a sailboat and a foiling kiteboard to show how apparent wind changes without relying on vector diagrams.

This longer video from Sailing Theory Tutorials uses a visual vector addition approach (without trigonometry) to explain apparent wind speeds at different points of sail.

When sailing upwind, how does the apparent wind angle change in a puff? In a lull? If you can’t answer these without racking your brain, this web page from the Cal Sailing Club has two animations to illustrate. 

Apparent Wind in a Puff – Velocity Lift

Apparent wind in a lull – velocity header, high performance boats.

We know that the apparent wind angle moves forward as boat speed increases. Here are two videos from America’s Cup teams using bicycles, land yachts, and AC 72s to show why fast boats don’t need spinnakers, since they’re always sailing upwind.

Apparent wind calculator

If you want to play around with the effects of true wind, boat speed, and heading, here’s a calculator from L-36.com . It’s designed for several purposes, but you can use it as an apparent wind calculator. Simply enter true wind angle, true wind speed, and boat speed to get the apparent wind angle and speed. Or you can enter apparent wind data to get the true wind.  

Related Content:

Sailors helping sailors.

Will you share your knowledge with your related Comments below?

Related Posts

Velocity Made Good (VMG) – Definition and Application

Mechanical Advantage in Sailboats: Block and Tackle Systems

Leave a comment cancel reply.

You must be logged in to post a comment.

This site uses Akismet to reduce spam. Learn how your comment data is processed .

[email protected]

• Course Login

RYA Online Courses

Apparent wind explained, apparent wind / true wind.

The issue of wind direction and strength becomes complicated as soon as a boat starts to move. Telltales and wind vanes on mastheads only indicate the true wind when a boat is stationary.

As soon as it starts to move they react to a combination of wind and the boat’s movement – apparent wind.

Fig 12a shows a vector diagram for a boat on a beam reach. The long side of the trapezoid represents 10 knots of true wind drawn to scale while the short side of the trapezoid shows the boat speed, 6 knots. The long diagonal represents the apparent wind. Note that the length of the line now shows 12 knots of wind speed and the angle of the wind crossing the boat has decreased to 60°. In order to maintain the same entry angle to the wind, the boat’s mainsail and jib had to be trimmed on -meaning, pulled in – progressively as the boat accelerated.

Fig 12b shows the apparent wind for the same conditions with the boat sailing close-hauled, at 45° to the true wind. You can see that the apparent wind builds significantly and the entry angle closes down as the boat accelerates forward to a full speed of 6 knots.

Fig 12c shows the same boat broad reaching at six knots in the same wind. This time the apparent wind decreases but the entry angle still closes down.

In all three of the illustrations the sails had to be considerably re-trimmed as the boat increased speed, and boat speed varies all of the time. Wind speed and direction are rarely constant, so it follows that, to keep a boat moving efficiently through the water, the sails need almost constant re-trimming to cope with the constantly changing conditions.

Remember, as soon as you start moving the windex or woolies will only show you the apparent wind. The same is true of the more basic electronic wind insruments. To display true wind information the wind instrument must interface with the log, or speed input.

The above is an extract from the RYA book “SAIL TRIM hanbook for Cruiers” which is avaialble from Sailtrain.

© Copyright Sailtrain Ltd 2024, All Rights Reserved | Sitemap | Privacy Policy

• Learn to Sail Memberships
• Private Lessons
• Online Learning
• Group Sails, Racing & Events
• Memberships
• Reciprocal Privileges
• Members Only
• Tahiti May 2024
• Croatia September 2024
• British Virgin Islands December 2024
• Skippered Sails
• Corporate Events

Apparent Wind

By andrew lesslie.

A question came up on the Spinnaker Forum about why the wind always feels less when it’s behind the beam.   This is an opportunity for us to dive into the concept of  apparent wind .

But first a quick definition.    True wind  is the wind we would feel if our boat were stationary, say if we were at anchor.  But if we’re out racing, we have our sails trimmed and we’re using that wind to create motion.     The wind we feel on our faces when we’re moving through the water is a combination of the air flow we feel from our own motion, plus the air flow from the true wind.  We call this combined wind the  apparent win d .  Apparent wind is the wind the boat feels and the wind that we trim our sails to.  We sail in apparent wind, so it’s kinda important that we understand it.

We can begin to appreciate the way that true wind speed and direction, combine with boat speed and heading to give us apparent wind and direction by considering the diagrams that follow.    In these illustrations we keep the boat orientation constant and rotate the wind around the boat.   Thus we preserve the sailors point of view as looking up the page in each example.

Credit : The illustrations I’ve used in this article were taught to me long, long ago by my Junior Race Program coach, Mr, Peter Conway.  I’ve not seen this style of illustration used in any books on sailing or racing, but think it offers a simple, accessible way to understand the relationships between True wind, Boat motion and Apparent wind.  While I’ve created these illustrations using computer tools, Peter would draw these on the concrete boat ramp using a yardstick, a piece of string and colored chalks.  As I was drawing each of these diagrams on my Mac, in my mind I could see the yardstick, string, chalk, and a half dozen wet, cold and shivering kids!

Calculating (or plotting) Apparent Wind Angle and Speed from True Wind Angle and Speed and Boat Speed and Direction

Note!  For ease, this explanation uses a simplified case of a constant boat speed and a constant wind speed.  Of course boat speed is not the same on all points of sail and we’ll expand the discussion to cover that later in the discussion. In this first case, let’s consider a vector diagram representing a boat at various angles to the true wind on Starboard tack.   For those who have forgotten high school trig, a vector diagram is an illustration where the length of a line represents velocity and the direction of the line represents an angle.  By considering the way the vectors combine, we can predict what we as sailors will experience on the boat.  Understanding how a boats motion combines with the wind is important to developing our understanding of how sailboats perform and especially to developing our racing strategy.

We can resolve vector combinations either by scale drawing or using mathematical formulae.    I’ve used scale drawings here so that we can lead the discussion into using Polar Charts later in the discussion.  I’ve included the mathematical formulae later so we can plug them into our computer or programmable calculator. (Or ignore them completely!).

First we draw a line representing our boat speed.   This is the blue line and it’s ‘five knots long’ and pointing directly up the page, representing our direction of travel.   We then draw an arc with its center at the tip of our boat speed vector, with a radius of 10 knots.   This arc represents the True Wind Speed and the range of possible wind angles we can sail, from close hauled to dead downwind.

We have selected four points on this arc and each represents a True Wind Angle.  We’ve plotted 45° (sailing to windward), 90° (sailing across the wind), 135° (a broad reach) and a mystery angle that we’ll get to in a little while.

This diagram helps us to readily determine the Apparent Wind Angle and Apparent Wind Speed simply by drawing a line from the base of the boat speed vector (the blue line) out to any point on the True Wind Arc.   The length of this line indicates the Apparent Wind Speed and the angle (in red) is the Apparent Wind Angle.  

That’s it.  It’s that simple.  Once chart and we can measure the AWA and AWS for any TWA at this Wind Speed and Boat Speed.

From this chart, we can see that when sailing at 45° to a 10 knot true wind we experience an apparent wind speed of 13.7 knots at an apparent wind angle of 30°.  These numbers are important to racers because we trim to wind speed and angle.  

Let’s consider other angles.    

If we sail at a right angle to the true wind, our AWS and AWA vector is the broken line connecting the base of the boatspeed vector to the 90° TWA point on the True Wind arc.  In this case we measure our AWS as 11.1 kts and our AWA as 65°

If we sail at 135° to the true wind, our AWS is 7.5 kts and our AWA is 108°

At our mystery angle where the apparent wind is abeam, we reverse the calculation.   By plotting, we connect the point on the TWS arc to the point of our boat speed vector and measure.   To sail with the apparent wind dead on the beam, we would sail to a TWA of 118°.   For example, if the wind is coming from 030°, we would sail a course of 30°+118°=148° to have the wind on the beam.

If we’re sailing one-design, these calculations help us understand if we’ll be able to carry a spinnaker on a given leg.   If we’re offshore racing on a boat with a full sail inventory, an idea in advance of the TWS and TWA to expect for each leg of the course gives us an idea which of our upwind or downwind sails we’ll want to have ready and which we put in the sail stack.

Let’s look at a downwind example, then use it to figure out whether we can carry our spinnaker in a Merit One-Design race.

Determining whether we can carry a spinnaker on a leg of a course

If we know from our experience that we can reach with our spinnaker to an apparent wind angle of 120° we can reverse the plot and work out what true wind angle we can carry it.   We can then compare the wind direction with the bearing of a leg on our race course and work out of the leg will be deep enough to set the spinnaker.   Let’s do that.

Now let’s put that into practice.    We’re racing out on the South Bay in a 10 knot wind that’s blowing from the NW.  The next leg of the course is from X to 2.  Will we be able to set the spinnaker?

We can use Navionics, OpenCPN, our paper chart or whatever to determine that the course from X to 2 is at a bearing of 175°(T).  This image is using the ‘measure’ feature in the free version of Navionics on the web ( https://webapp.navionics.com ). The data is the same as the mobile version and some kind user has put the SYC racing marks into the app.  

Other apps offer similar functionality, but you might have to add your own marks.

We also know that NW, when expressed in degrees is 315°(T) and the course from X to 2 is 175°T.  Yes, the math is simple in this case, but plotting it on a compass rose makes it crystal clear.

From our earlier calculation, we know the limit for our spinnaker is 145° and our calculation above says the TWA on the leg from X to 2 will be 140°.

This creates a tactical dilemma.   Do we try to fly or not?  Marginal spinnaker legs are challenging and we might opt for caution.  Or, we might hoist, sail as deep as we need to, knowing we’ll be sailing 5° or low of the mark and will need to drop the spinnaker and head up under jib later in the leg (consider this a strong tactical hint!).

Creating an AWA / BoatSpeed cheat card from a Polar Diagram

Post race discussions around the sailing club fireplace often turn to polar charts and how they can be used to improve racing performance.   I’ve never seen anyone consult a polar chart while out racing, but it’s certainly possible to extract the data and use it to create ‘reference cards’ for a given boat.

To keep this as relevant as possible to One-Design racing at Spinnaker, I’ve used the Polar chart for the J/24, as the performance is close enough in most conditions (The J/24 is stiffer and quicker upwind, but off-wind, they’re equal).

Below is a picture illustrating the different components of a Polar Chart.

The background of the chart shows a range of true wind angles and check marks radiating out from the origin that in this case represent boat speed.  The plot lines represent the speed that the boat can achieve at a given true wind speed and angle (boat speed curves).  A plot is drawn for each wind speed, as indicated on the lower axis.  This chart has plots for windspeeds of 8, 10, 12, 16 and 20 knots.

To read the chart pick a windspeed and a true wind angle.  Let’s use 10 knots and a TWA of 75°.  We look for the point where the 10 knot plot line crosses the 75° TWA line and we read off the value from the boat speed scale (distance from the origin).   We see that the prediction is that we should be able to sail at 6.5 knots. Easy, huh?

Where the date from polars is really useful is in downwind spinnaker legs, where we have an option to sail at a variety of angles to the wind.  It should be a given for races in a spinnaker fleet to know that the fastest way to get from the windward to the leeward mark is not a dead down-wind course.   Note that when sailing with jib and main only, the direct line usually is the fastest course.

What’s challenging about polar charts is that by convention, they’re plotted against True Wind, but we sail in apparent wind.  I have no idea why the decision was taken to plot against true wind, it wasn’t me who made that decision!  Plotting against apparent wind would have been much more useful.

So.    How can we convert from TWA to AWA? If you buy a boat with a high-end chart plotter, these calculations are built into the computer that lives inside it.  You merely have to load the polar data for the boat into the computer and it’ll tell you exactly what angles to sail and whether you’re sailing too high or low.   But where’s the fun in that?  And even if you have one, it’s good to understand the calculations it’s doing on your behalf, right?

Let’s take our J/24 polar diagram and overlay our true to apparent vector triangle.  We read the boatspeed directly off the speed plot and see it’s 5.1 knots.  So we draw the blue boatspeed line at 5.1kts and then connect the base to the arc representing 10 kts of true wind speed.   Then we plot the apparent wind line to the other end of the boatspeed vector and we have our apparent wind speed and direction.

So now we know TWA, TWS, Boatspeed, AWA and AWS for the optimal downwind angle for 10 knots of wind.   Why would we care about knowing the AWA? Because on a boat that has no instruments, but has a masthead fly (like, say a Merit 25) we now have a way to judge whether we’re sailing the best angle downwind.

In 10 knots of wind, we should strive for a boat speed of just over 5 knots at an apparent wind angle of 142°.

Building out a complete AWA, AWS table

We can repeat this plot (or calculation) for each windspeed that’s listed in the polar table and the outcome is shown below.   Note that this is a standard table built from the rating certificate for the J/24.  Also below is an illustration of TWA and Gybing angle.

How would we use this? When racing a Merit 25 with a spinnaker, there is much to be gained (or lost) on the downwind legs and judging gybing angles is less familiar to most skippers than judging tacking angles. If you like keeping things simple, here’s what you’ll want to know:

In light winds of 6-8 knots, sail downwind with the windex showing apparent wind 10°-15° behind the beam and  no faster than 5 knots .   If you’re going faster, head lower. In moderate winds from 10-12 knots, sail downwind with the windex showing apparent wind about half way between abeam and dead astern and no faster than 5.5 knots.   If you’re going faster, head lower. If sailing under jib and main ,  sail almost directly downwind, heading up only enough to keep the jib from collapsing ,  AWA 165°-175°

Doing the math For those who prefer calcs to measuring lines on charts, here are the formulae to resolve AWS (A) and AWA (?).

Learn About Upcoming Events

• 451 Seaport Court
• Redwood City, CA 94063
• 650-363-1390
• Rich Ferrari, The Chief
• Bob Diamond, School and Vacations Director
• Dana Ochstein
• Instructors
• Redwood Landing Marina

Copyright © 2021  Spinnaker Sailing Inc. All Rights Reserved.

Apparent Wind

The very first sailing physics topic that I need to convey to you is the idea of apparent wind velocity. This notion is absolutely fundamental for an understanding of sailing vessel movement. Fortunately, it is a simple idea and one that already will be very familiar to those of you who sail. I will state the case, nevertheless, because we will require the concept very soon when seeking to understand how wind provides drive for square-riggers. Even if you are thoroughly at home with apparent wind, there may be something for you to learn in this section, and it will serve to tell you about my notation.

Albert Einstein was a keen recreational sailor (fig. 2.1). This fact is pertinent to my discussion of apparent wind because apparent wind is all about relativity, a subject that the good professor (who appeared a little windblown most of the time) knew something about. Interestingly, the relativity theory pertinent to apparent wind is not that of Einstein but of a much earlier scientist whom Einstein greatly admired: Galileo. Galilean relativity is basic common sense: if you are driving along at 30 mph and another car is coming toward you at 40 mph, then your relative speed is 70 mph. Prof. Einstein would disagree,1 but that's life; we will go with Galileo. Now, to extend this idea to a two-dimensional sea surface rather than a one-dimensional road, we need to describe velocities by vectors. The notion of apparent wind is explained simply in vector notation in figure 2.2a.

I need to be careful about nomenclature: to a physicist speed refers to how fast an object is moving, whereas velocity refers to both how fast

and in what direction it is moving. So, in figure 2.2a the arrows represent wind velocity, whereas the arrow lengths represent wind speed. The angle between boat velocity, v, and true wind velocity, w, is avw. (Throughout the book I will denote vector quantities like velocity with underlining.) The wind velocity felt by the moving boat is not w but rather w% = W—v; the boat moves through the wind and so feels a wind velocity that depends on its own speed and direction, as well as that of the wind. Consider what happens if aw = 0°, in other words, if the boat is

Figure 2.2. (a) Our boat moves with velocity v, in a wind with true velocity w. She feels an apparent wind w'. (b) The boat has now changed direction and is heading upwind with the same speed: note how the apparent wind speed increases. (The dashed line shows how vector addition works.) In both cases the boat heading is closer to the apparent wind direction of origin than to the true wind direction of origin.

running before the wind. In this case she feels a following wind of reduced speed, as you might expect. If, as illustrated in figure 2.2a, the point of sail is a broad reach, then apparent wind velocity, W, has a different direction, as well as a different speed, from true wind velocity, w. If, as in figure 2.2b, the boat is close hauling (i.e., sailing into the wind), the apparent wind speed is greater than true wind speed. In the two cases shown in figure 2.2 the boat speed is the same; only the direction is different. Yet this difference produces very different apparent wind ve locities. The effect of boat velocity is always to make the apparent wind seem more head-on than the true wind, which is fairly obvious if you think about it.

Continue reading here: Wind Force Boat Force and Isaac Newton

Was this article helpful?

Related Posts

• Analysis Square Rigged Ship Motion
• Apparent Wind vs Course - Catamarans Guide
• Understanding Apparent Wind
• The Age of Exploration Carrack and Caravel

• Cruising Compass Media Advertising & Rates
• Blue Water Sailing
• Multihulls Today
• Subscribe Today

Calculating the True Wind and Why it Matters

There are several ways to define the wind. For weather work at sea we care only about the true wind. This true wind is the speed and the direction of the wind relative to the fixed earth under the ocean. Tied up at the dock, we feel the true wind. Once we get underway, however, our own motion changes the wind we feel, and then it is called the apparent wind.

Many sailors claim that the apparent wind is all they care about, and that can be well argued when it comes to setting sails and judging performance. But to know about the weather patterns that are causing the wind and how the wind is changing, we need to know the direction of the true wind as accurately as possible. Shifts in the true wind are usually the first sign of changing patterns. If we do not figure this properly, we can miss an important shift. This is not a simple observation though, which is the point at hand. Slight changes in true wind speed affect boat speed, and in turn, the apparent wind speed and direction, which can easily mask a small but important shift in the true wind direction.

To help practically illustrate these points, let’s bring in some shorthand:

AWS = Apparent Wind Speed (relative to the boat) AWA = Apparent Wind Angle (relative to the bow, 0 to 180, starboard plus, port minus) AWD = Apparent Wind Direction (relative to true north)

S = Knotmeter speed (relative to the water) H = Heading (relative to true north)

DFT = Current Drift (speed, relative to fixed earth) SET = Current Set (direction it flows toward, relative to fixed earth)

SOG = Speed Over Ground (relative to the fixed earth) COG = Course Over Ground (relative to the fixed earth)

TWS = True Wind Speed (relative to the fixed earth) TWD = True Wind Direction (relative to true north)

Since wind directions are almost always discussed in terms of true directions, not magnetic, we’ll forget the compass for now and consider all directions as being true. Our actual use of compass directions in navigation does indeed complicate things a bit, but that can be sorted out later as it is not really related to the subject at hand.

To review the issues involved, we’ll start with a basic example. It can be dead calm at the dock, and I take off under power headed due north with my knotmeter reading 5.0 knots, and sure enough, I will have 5.0 knots of apparent wind right on the bow. S = 5.0, H = 000, AWS = 5.0; AWA = 0, implying AWD = 000.

If I then turn to H = 090, I will still have AWS = 5.0 and AWA = 0, but now the AWD = 090. So, if there is no wind at all, I am creating it all myself.

A bit closer to the point at hand, I could do this same thing, still with S = 5 knots and then I notice that I have AWS = 7.0 knots, still with AWA = 0. Something changed. I check the GPS and see that my SOG = 7.0 knots, and that accounts for the extra wind. I am in a current that is moving the boat at 2.0 knots. Now I need to look at the COG. If the COG is exactly equal to my Heading, then this current is directly on my stern, pushing me forward at DFT = 2.0, SET = 090.

Now, if I shut off the engine and slow to S = 0, with H = 090, I should see AWS = 2.0, still with AWA = 0, providing the COG = 090, and SOG = 2.0 (still H = 090), and I can conclude that I have measured two things: The true wind is calm, and the current is setting toward 090 at 2.0 knots. If this were not the case, one of these numbers had to be different.

When TWS is not zero, this analysis gets more complex and a vector triangle must be solved, but the key point is always the difference between COG and H. If COG = H, meaning you are moving the direction you are headed, then all of the standard vector triangle solutions for finding true wind will work fine. You just substitute SOG for the S that is in the equations or plotting routines.

Generally, these formulas and plotting routines solve for true wind angle (TWA) based on AWA, AWS and S. Then you apply the TWA to H to get the TWD. That all works fine in those cases, and there are numerous resources online, such as the one included in what we call the NIMA Nav Calculators, which is a free download at  www.starpath.com/navpubs .

Also, it seems to me that the typical equations we see in books (including my own) that use some form of the Law of Cosines might not be able to handle all the various combinations of directions in this case. It seems safer to get the answer from x-y coordinates, and so we present these formulas, written in a way that can go directly into a spreadsheet or calculator.

AWA = + for Starboard, – for Port AWD = H + AWA ( 0 < AWD < 360 )

u = SOG * Sin (COG) – AWS * Sin (AWD) v = SOG * Cos (COG) – AWS * Cos (AWD)

TWS = SQRT ( u*u + v*v )

TWD = ATAN ( u / v )

Remember, in a spreadsheet all the angles have to go in as radians, i.e. COG = COG(º)*(Pi/180). In a spreadsheet you can write AWD = MOD(H+AWA;360).

However, it is likely simpler to plot it with actual bearings, rather than as a relative plot using COG as 000. Below is a sample. It is the green triangle that you plot, i.e. plot SOG/COG and plot AWS/AWD and connect the end points to get TWS/TWD.

The spreadsheet format that computes everything will make it easier to experiment with various interactions of sailing and current to see how this affects the final outcome. You can download a copy of this spreadsheet with the equations in it at the tech support page for Modern Marine Weather ( www.starpath.com/weatherbook) .

Keep in mind that these measurements assume the instruments are calibrated and the wind sensors are located away from disturbing wind from the sails or other rigging on a power driven vessel. We have seen cases where the masthead instruments are affected by updrafts from the sails, which is why some race boats use a rather large arm holding the instruments a good distance off of the masthead.

One easy test is to measure true wind on one tack compared to the other tack as you tack back and forth in smooth water. This exercise might expose other important issues too, namely that your speed varies noticeably on each tack, implying that the speed sensing is not purely symmetric––assuming the sails are. In big waves, you often expect the speed to be different on opposite tacks, but if the speed sensors and sail trim are working properly, the true wind should be the same on each tack or gybe.

Ben Ellison has pointed out ( www.panbo.com ) that many performance sailors prefer to know the wind vector relative to the water as opposed to the fixed ground below it, which is what we would get by simply using S for SOG and H for COG. This is the way many instruments compute this data, though many models now offer options. He proposes to call this wind the Water Wind, as opposed to True Wind (which as shown above is not correct), and then do away with the term True Wind and call that Ground Wind.  There is clearly logic in this terminology, and it drives home the point that we should think on these differences. We will have to see how the sport and industry responds.

I am old fashioned in these matters, and will likely stick with true wind, and just check that it is computed properly when it matters. But then, I still use GMT when I should say UTC1.

David Burch is the director of Starpath School of Navigation, which offers online courses in marine navigation and weather at  www.starpath.com . He has written eight books on navigation and received the Institute of Navigation’s Superior Achievement Award for outstanding performance as a practicing navigator.

Administrator

You might also like.

Mustang Introduces New Hydrostatic Offshore Inflatable PFD

Fountain Pajot-Dufour Yachts Group Makes Commitment to Carbon Neutrality by 2030

Orca 2 Nav System Expands Capabilities

Read the Summer-Fall Edition of Blue Water Sailing

Read the fall 2023 edition of blue water sailing, recent posts.

• Commercial Sailing Cargo Ship on Maiden Voyage from France to New York

• Survey of the Week

Please Visit Our Sponsor’s Webpages

• Media Advertising & Rates

Published by Blue Water Sailing Media, a division of Day Communications, Inc., Middletown, RI

Publisher & Editor: George Day

Blue Water Sailing Media publishes Blue Water Sailing magazine, Multihulls Today and other titles.

Cruising Compass Advertising Sales:

George Day, Newport, RI [email protected] 401-847-7612

• Sail Cargo Building a Sustainable Sailing-Ship Cargo Business
• A Naturalist’s Look at the Amazing Galapagos Islands

© 2014 Blue Water Media. All rights reserved. | Admin

• Sailing to the Wind: Mastering the Art of Wind Direction in Sailboating

Sailing is not merely a recreational activity; it's a blend of skill, art, and a deep understanding of nature's forces. At its core lies the intricate relationship between a sailboat and the wind. In this comprehensive guide, we will explore the various aspects of sailing in relation to wind direction, helping you become a seasoned sailor. So, grab your captain's hat, and let's set sail!

The Basics of Wind and Sailing 

Before delving into the finer details, let's establish a fundamental understanding of wind and its role in sailing.

The Wind's Influence

Wind is the lifeblood of sailing. It propels your sailboat and determines your course. Understanding its nuances is essential.

Points of Sail

To sail effectively, you must be familiar with the points of sail - the different angles at which your sailboat can harness the wind.

Wind Terminology

Before we proceed, let's clarify some essential wind-related terms you'll encounter throughout this guide:

• True Wind : The actual wind direction and speed relative to the Earth's surface.
• Apparent Wind : The wind experienced on a moving sailboat, which combines the true wind with the boat's forward motion.
• Close-Hauled : Sailing as close to the wind as possible while still maintaining forward motion.
• Running : Sailing with the wind directly behind you.
• Reaching : Sailing at an angle to the wind, not too close or too far.

Sailing into the Wind 

One of the most challenging maneuvers in sailing is "sailing to the wind," also known as "close-hauled sailing."

The No-Go Zone

Discover the "no-go zone," a critical concept in sailing close to the wind, and how to navigate it successfully.

Beating and Tacking

Learn the techniques of beating and tacking, essential for making progress against the wind.

Balancing Act: Sail Trim

Achieving the perfect sail trim is crucial when sailing into the wind. We'll delve deep into this critical aspect of close-hauled sailing.

Read our top notch articles on topics such as sailing, sailing tips and destinations in our Magazine .

Check out our latest sailing content:

Sailing Away from the Wind 

Sailing away from the wind is a different beast altogether, requiring a distinct set of skills.

Running Before the Wind

Explore the exhilarating technique of running before the wind, where you sail with the wind directly behind you.

Discover reaching, a technique used when sailing at an angle to the wind. It's all about harnessing the wind's power efficiently.

Wing and Wing: A Masterclass

Wing and wing sailing is a technique where you set sails on opposite sides of the boat when running before the wind. We'll teach you the intricacies of this advanced maneuver.

Understanding Wind Direction

To become a master sailor, you must comprehend wind direction thoroughly.

Reading the Wind

Unlock the secrets of reading the wind, including observing natural indicators and using wind instruments.

The Role of Sail Trim

Learn how adjusting your sail's trim can optimize your sailboat's performance, depending on the wind's direction.

The Wind and Weather 

Explore how different weather conditions affect wind patterns and, consequently, your sailing experience.

Sailing Challenges 

Sailing isn't always smooth sailing. Explore common challenges and how to overcome them.

Sailing Without Wind

Discover strategies for sailing when the wind seems absent, ensuring you don't get stranded at sea.

Sudden Wind Shifts

Learn how to adapt swiftly to unexpected wind shifts, preventing potential disasters.

Dealing with Strong Currents

Incorporate knowledge of currents into your sailing skills to enhance your ability to navigate challenging waters.

Navigating Windy Waters 

Sailing in windy conditions requires a unique set of skills.

Sailboat Stability

Understand the importance of maintaining sailboat stability, especially in gusty winds.

Advanced Wind-Handling Techniques

Explore advanced techniques for handling your sailboat in challenging windy conditions.

Safety First: High-Wind Precautions

When the wind kicks up, safety should be your top priority. Learn how to secure your sailboat and crew in high-wind situations.

In the world of sailing, mastering wind direction is akin to unlocking a treasure chest of endless possibilities. Whether you're tacking close to the wind or running before it, understanding the wind's whims will make you a more confident and capable sailor.

But remember, as with any skill, practice makes perfect. So, hoist your sails and embark on a journey to harness the power of the wind.

So what are you waiting for? Take a look at our range of charter boats and head to some of our favourite  sailing destinations.

I am ready to help you with booking a boat for your dream vacation. Contact me.

Denisa Nguyenová

No products in the cart.

Sailing Ellidah is supported by our readers. Buying through our links may earn us an affiliate commission at no extra cost to you.

True And Apparent Wind Speed Explained

True wind speed is the actual wind velocity measured by a stationary object. Apparent wind speed is the wind velocity perceived by an object moving through the air, such as a boat or yourself. In other words, apparent wind speed combines the actual wind and the effective wind created by your motion.

So why is this so important in sailing?

Let me explain.

Understanding the difference between true and apparent wind

What might feel like a chill and relaxed Sunday sail off the wind can turn into an intimidating and challenging experience if you have to turn around and sail upwind. When you understand how the wind works on a moving object like a sailboat, you can consider it when planning your trip or deciding whether to go or wait for better conditions. 

The angles we sail relative to the wind and the wind created by our speed over the ground equals the apparent wind we experience onboard. And on a sailboat, we sail and trim the sails according to the apparent wind.

Our apparent wind speed changes when we adjust the course and angle towards or away from the wind direction. Our boat speed also affects the apparent wind angle. This can be confusing in the beginning. To fully understand how the wind speed and direction affect us on a sailboat, we first have to familiarize ourselves with the compass rose and learn some terms.

The compass rose explained

We often talk about wind direction in terms of the cardinal points in the compass rose.

The most normal to use are the following:

Knowing your compass rose is essential when sailing and navigating at sea!

These are commonly known and used by most. However, specifying the angle in degrees is much more accurate. It is also what you will read from your sailing instruments and the weather forecasts.

True wind explained

So, precisely what is true wind?

True wind is the wind that affects you when you are stationary . When we talk about wind in general, we usually refer to  true  wind speed, direction, and angle. Using nautical terms makes it easier to identify the specific element we are talking about.

These are the terms used about true wind:

• TWS  – True Wind Speed
• TWD  – True Wind Direction
• TWA  – True Wind Angle

The wind speed is usually measured by a wind anemometer in knots, meters per second, kilometers per hour, or miles per hour. For us sailors, knots are the most commonly used measurement as it makes calculations regarding speed in knots easy. Here you have the conversions:

Wind speed conversion:

10 knots = 5.14 m/s = 18.52 km/h = 11.50 mph

If the wind is blowing 10 knots north-easterly, the wind comes  from  the northeast, which is a 45-degree direction (TWD), blowing 10 knots (TWS). If you sail on a south-easterly heading, the vessel’s angle to the wind (TWA) is 90 degrees.

However, since we move in direction and speed when we sail, the apparent wind always behaves differently than the true wind.

Apparent wind explained

So, precisely what is apparent wind?

Apparent wind is the wind that affects you when you are moving . It combines the true wind and the effective wind created by your motion. The apparent wind will vary from the true wind depending on the angle and speed of your movement.

Here are the terms used about apparent wind:

• AWS  – Apparent Wind Speed
• AWD – Apparent Wind Direction
• AWA  – Apparent Wind Angle

Think about this:

You are standing still, and the wind blows 10 knots. If you start to run against the wind, it feels stronger. If you run away from the wind, it feels weaker. That is because even though the actual breeze is consistent, the apparent wind changes.

Let’s give some examples.

Apparent wind vs. true wind

Imagine the following scenario:

The  TWS  is  15  knots, and the  TWA  is 0 degrees, or straight from the north. You are sailing at 5 knots straight south, away from the wind. Your  AWS  will, in this case, be 10 knots.

If you turn around 180 degrees and motor straight north into the wind, your  AWS  will increase by the 5 knots of speed you are making and rise to 20 knots.

So, what about the angles?

Let your brain process this for a bit.

The elements work against us when we sail to some degree. This is where most fresh sailors’ plans fail. I have been there myself. However, don’t be disappointed in your boat’s ability to sail close angles. You can read more about how high a sailboat can point here.

Just take the facts for what they are and work with them to plan your routes.

The correlation between actual and apparent wind speed

Finding the correlation between actual wind speed and apparent wind speed in an angle requires us to calculate some vectors, which is unnecessary.

Luckily, Most boats today have wind instruments that do this job for us and show us all the information we need.

However, if you want to squeeze your brain around vector calculations, this is a good source from Spinnaker Sailing.

The most important thing is to know how to use this information. When you sail downwind, it might seem like it is just blowing a breeze. But that is only until you turn around and realize your apparent wind has increased significantly. 

You need to know and prepare for this. Maybe you should reef your sails before turning around?

When you sail, you sail to your apparent wind, as that is the wind that affects your boat in motion. But always keep an eye on the actual wind speed, especially when sailing downwind!

The video below shows an example of smooth 20 kt wind on a 90-degree beam reach while enjoying the Caribbean waters sailing above 8 knots!

Final words

Most people are familiar with true wind or actual wind. Understanding apparent wind is a bit more complicated. I hope you now understand the difference between the two and why it matters. Now, it is time to continue and learn how to sail at different angles to the wind. That brings us to the five points of sail, which you can read about in this guide .

Sharing is caring!

Skipper, Electrician and ROV Pilot

Robin is the founder and owner of Sailing Ellidah and has been living on his sailboat since 2019. He is currently on a journey to sail around the world and is passionate about writing his story and helpful content to inspire others who share his interest in sailing.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

• Work & Careers
• Life & Arts

Heartbreaking Hannah Lynch detail emerges as rescuers shed new light on Bayesian yacht sinking

Hannah Lynch was among seven people killed in the Bayesian yacht disaster, which saw the boat sink off the coast of Porticello, near Palermo in Italy amid stormy weather

• 19:16, 24 Aug 2024
• Updated 19:30, 24 Aug 2024

A teenager dead in the Bayesian yacht disaster was found alone in her own cabin on board the superyacht, it has emerged.

The 18-year-old woman, who this month received her A-level results and was set to go to University of Oxford, was among seven tourists, including her tech tycoon dad Mike, declared dead after the disaster .

The boat sank 50 metres below the surface of the Mediterranean, said rescue workers at a press conference today. All the other tourists were found in a separate compartment on the Bayesian superyacht, fire service commander Girolamo Bentivoglio Fiandra told the reporters at the same briefing in Italy.

The £30million vessel lopped onto its side as it sank - and Mr Fiandra said it became apparent to divers that the victims of the disaster had tried to seek shelter in the higher side of the ship, where there may have been air bubbles, before they died. Manslaughter probes have now been launched into the deaths.

Investigators have so far declined to comment on why five of the dead were found in the same room. Those on the panel said the cabin room they were found in was not theirs.

Hannah, whose former school paid an emotional tribute to the woman , had been on board the ship with her father and mother as well as other high-profile businessmen and their spouses when the ship was struck by a suspected downburst - a violent downward plume of wind - in the early hours of Monday.

Their bodies were recovered over the course of this week, taking the death toll from the disaster to seven after the ship's cook was found in the water close to the wreck site shortly after the disaster unfolded. Autopsies are yet to take place.

A manslaughter probe has been launched and lead prosecutor Raffaele Cammarano said officials had not conducted and drug tests on the survivors, but said that they would be interviewed to find out exactly why seven lives were lost. He said: "We are going to discover how much they knew or to what extent all the people were warned."

The Bayesian is believed to have sunk at the stern after being upset by a downburst that spread out with force as it hits the ground after being produced in the clouds, before coming to rest on its right-hand side as it capsized.

Fire chief Mr Fiandra said in remarks reported by Sky News: "You may want to know where we recovered the bodies of the victims. I can tell you... that the ship sunk and was laid onto its right hand side at the bottom of the sea.

"It's quite clear that the people were trying to hide in the cabins on the left-hand side and we found the first five bodies in the first cabin on the left-hand side and the final body in the third cabin on the left-hand side.

"There were six cabins: three on the left-hand side and three on the right-hand side. We found them on the highest part of the ship going towards the surface."

MORE ON Hannah Lynch Mike Lynch Italy Bayesian yacht

Get email updates with the day's biggest stories.

This article is an excerpt from NauticEd’s online FREE Basic Sail Trim Course , an interactive online sailing course for beginner to intermediate sailors to learn the basics of sail trim. Or if you want to learn more, upgrade to the Skipper Course Bundle to become a competent sailor!

You can learn to sail and improve your sailing with NauticEd, the international leader in sailing education.

True Wind vs. Apparent Wind

We’ve created an interactive animation here so that you’ll instantly “get” what everyone tries to explain laboriously on a blackboard without much success.

Click and drag on the slider bar. As the car speeds up, the wind increases in velocity and the direction of origin feels like it moves forward. That’s apparent wind – it’s what your hand feels out of the window and on a boat it’s what the sails feel. If you stop the car, the apparent wind goes back to be the same as the true wind. The true wind stays the same regardless of your speed. That’s it! Now you understand true versus apparent wind.

Our more complex animations are best experienced in Chrome, Firefox, or Safari.

Figure 1.2-1 Animation of a Car Moving in Wind

Just one thing to note which you’ll use later on in this sailing course. Observe that the true wind is always coming more from the back end of the car. It’s the same on a boat. When you’re moving along and point to where the apparent wind is coming from, the real true wind will be coming from further towards the back of the boat. As a general (really general) rule of thumb (unless you’re going downwind), if you point about 15 degrees back from the apparent wind – that’s about (double about) the direction of the true wind. The true wind is said to be “Aft” of the apparent wind.

Learn Basic Sail Trim for FREE...

A FREE 1-2 hour course that teaches how to work with sails to get your boat moving. The free Basic Sail Trim Course is for any aspiring sailor as well as experienced sailors wanting to learn more. Or, consider upgrading to the Skipper Course Bundle to become a fully competent skipper!

My vision for NauticEd is to provide the highest quality sailing and boating education available - and deliver competence wherever sailors live and go.

TWEET ABOUT

FIGHT CHILDHOOD CANCER

NauticEd is a fully recognized education and certification platform for sailing students combining online and on-the-water real instruction ( and now VR ). NauticEd offers +24 online courses , a free sailor's toolkit that includes 2 free courses, and six ranks of certification – all integrated into NauticEd’s proprietary platform. The USCG and NASBLA recognize NauticEd as having met the established American National Standards. Learn more at www.nauticed.org .

The NauticEd Vacations team are Expert Global Yacht Charter Agents – when you book a sailing vacation or bareboat charter through NauticEd, we don’t charge you a fee – we often save you money since we can compare prices from all yacht charter companies. PLUS, we can give you advice on which destination or charter company will suit your needs best. Inquire about a Sailing Vacation or Charter .

Online Sailing Courses Sailing Vacations | Charters Practical Sailing Courses Sailing Certification | License

Sign up for 2 FREE Sailing Courses Try sailing in Virtual Reality! Gift a Friend a Sailing Course Sailing Events | Opportunities

About NauticEd Contact Us NauticEd Support Privacy Policy

A ‘Tornadic Waterspout’ Likely Sank a Billionaire’s Yacht Near Sicily. Here’s What That Means

Scientists say the extreme weather phenomenon could grow more common as climate change brings warmer water temperatures and more intense storms to the Mediterranean

Rudy Molinek

Mass Media Fellow, AAAS

The Phoenicians, who sailed the Mediterranean Sea 3,000 years ago, often used a stretch of water east of Palermo, Sicily, as a safe harbor . The area is protected from the strong, cold winds that blow southeast out of France. More recently, the anchorage has become a haven for billionaires and their yachts. But that safety was shattered this week with the sudden sinking of tech magnate Mike Lynch ’s yacht, the Bayesian .

Around 4 a.m. local time on Monday, a sudden and violent storm rocked the calm waters. Local residents tell the New York Times ’ Emma Bubola and Michael J. de la Merced that the storm brought some of the strongest winds they’d ever experienced—it “felt like an earthquake.”

Minutes later, the yacht was underwater. Of the 22 people aboard, local responders rescued 15, recovered six bodies— including Lynch’s on Thursday—and are still searching for his 18-year-old daughter.

Fabio Genco, head of the Palermo Emergency Medical Services, was one of the local responders who treated the survivors. “They told me that suddenly they found themselves catapulted into the water without even understanding how they had got there,” he says to NBC News ’ Claudia Rizzo, Claudio Lavanga and Yuliya Talmazan. “The whole thing seems to have lasted from three to five minutes.”

Meteorologists have since suggested the ship was sunk by a spinning column of air and moisture called a “tornadic waterspout.” The extreme weather phenomenon is brought about by warm sea surface temperatures during a storm.

This powerful event lasted just minutes and hit only a small area, sparing a boat moored just a short distance from the Bayesian yacht. The waterspout’s sudden onset would have caught the crew by surprise, especially at such an early hour, experts say. “Episodes of such speed and intensity mean that even if you are prepared, it is difficult to react in time,” Luca Mercalli , the president of the Italian Meteorological Society, tells the Guardian ’s Angela Giuffrida.

Waterspouts tend to form above warmer waters , and their cylindrical structures take shape as rising humid air is spun into a vortex by incoming winds. Intense tornadic waterspouts, like the one that sank the Bayesian , occur in association with severe thunderstorms. They are “often accompanied by high winds and seas, large hail and frequent dangerous lightning,” according to the National Oceanic and Atmospheric Administration .

While predicting any individual waterspout is nearly impossible, since it’s such a small phenomenon, scientists can use models to foresee the conditions under which they’re likely to occur. Meteorologists look for warm, moist air, changing wind and an instigating factor like a cold front that can set off the storm. This combination of conditions is becoming more common in a changing climate that’s warming with the emissions from burning fossil fuels.

For the last two months, the region where the Bayesian sank has experienced extreme heat. Sea surface temperatures have hit 86 degrees Fahrenheit, or about 5.4 degrees above average. “With a high sea-surface temperature (as in the case of a heatwave), there is more energy for storms,” Bogdan Antonescu , an atmospheric physicist at the University of Bucharest in Romania, says to the Conversation ’s Jack Marley.

This weekend, a burst of cold air broke the heat and brought heavy thunderstorms to Sicily. With the warm water below, conditions were ripe for a disastrous waterspout.

“Sea temperatures of three degrees higher means an enormous quantity of energy for storms,” Mercalli tells the Guardian . “ And when cold air arrives, it’s explosive.”

Get the latest stories in your inbox every weekday.

Rudy Molinek | READ MORE

Rudy Molinek is  Smithsonian  magazine's 2024 AAAS Mass Media Fellow.

Superyacht sinks latest: Investigators reveal where bodies were found as probe looks at 'crew's responsibility'

Italian officials revealed at a news conference there could be "a question of manslaughter" as they opened a shipwreck investigation and said the probe is also looking at the "crew's responsibility".

Saturday 24 August 2024 18:33, UK

• Superyacht sinking

Please use Chrome browser for a more accessible video player

• Prosecutor: There 'could be a question of manslaughter'
• Probe 'concentrating' on crew's responsibility
• Seven bodies recovered after five-day search of superyacht wreckage off Sicily
• Saturday's papers pay tribute to youngest victim Hannah Lynch
• Hannah's sister pays tribute to 'my little angel'
• Explained: Inside the superyacht | What challenges have faced divers?
• Eyewitness: Sombre scenes greet rescue teams as final body is brought ashore
• Live reporting by Niamh Lynch

We're ending our live coverage for this evening but here is a recap of what we know:

• Prosecutors have opened a manslaughter investigation into the Bayesian sinking;
• Officials have revealed more details on their investigation and the difficult five-day rescue mission;
• The six bodies found during the search in recent days were all in cabins on the left-hand - and highest - side of the ship. Five were found in the first cabin and the sixth was found in the third;
• Prosecutors said the six passengers were most likely asleep when the boat sank;
• The probe is now focusing on the crew and their responsibilities, with the captain set to undergo more questioning.

Monday 19 August

The Bayesian yacht, flying a British flag, sinks at around 5am local time when the area was hit by a tornado.

Fifteen people are rescued from the 56 metre vessel - including a mother and baby - but another seven remain missing.

One body, later confirmed to be the yacht's chef Recaldo Thomas, is found near the wreck.

It emerges that British technology tycoon Mike Lynch and his 18-year-old daughter Hannah are among six people that remain missing.

Tuesday 20 August

The search continues for the six tourists missing.

It is reported that among those missing are Morgan Stanley International chairman Jonathan Bloomer; his wife, Judy Bloomer; Clifford Chance lawyer Chris Morvillo; and his wife, Neda Morvillo.

Police divers try to reach the hull of the ship, resting at a depth of 50 metres.

Italy's fire brigade Vigili del Fuoco say early inspections of the wreck were "unsuccessful" because of limited access to the bridge and furniture obstructing passages.

The operation is later described as "complex", with divers limited to 12-minute underwater shifts.

Tributes pour in for Mr Thomas, with his friend Gareth Williams saying: "I can talk for everyone that knew him when I say he was a well-loved, kind human being with a calm spirit."

Wednesday 21 August

The search for the six people unaccounted for enters a third day, with crews carrying out inspections of the yacht's internal hull.

A team of four British inspectors from the Marine Accident Investigation Branch (MAIB) arrive in Porticello to look at the site of the sinking.

A helicopter is drafted in to help with the search effort and remotely controlled underwater vehicles are being used, with naval units and cave divers also taking part in the search.

Five bodies are found inside the yacht on Wednesday afternoon. Only four of them are brought to shore.

Body bags are seen being taken to Porticello in the afternoon where dozens of emergency services staff wait.

Searches finish for the day just before 7.30pm.

Thursday 22 August

The search resumes for the remaining missing person.

The body of the fifth missing person, found but not recovered the previous day, is brought to shore.

A fire service boat with flashing blue lights returns with a blue body bag to the port of Porticello just after 8.45am local time on Thursday.

Tributes pour in for Mr Lynch and Mr and Mrs Bloomer after they are identified as having died.

The search is called off at around 8pm in Sicily, with divers expected to begin again at 6.30am on Friday.

Friday 23  August

The search continues for the final person missing from the wreck of the Bayesian, Hannah Lynch.

Vincenzo Zagarola, of the Italian Coastguard, says the search for Hannah has not been "easy or quick", comparing the sunken yacht to an "18-storey building full of water".

The coastguard confirms in the late morning that her body has been found.

A green body bag is brought to the port of Porticello from the site of the sinking.

A spokesperson announces on behalf of the Lynch family that they are "devastated" and "in shock" after the deaths of Mike and Hannah.

Hannah's sister Esme pays tribute to her "little angel".

Saturday 24 August

A press conference is held in the court of an Italian town, Termini Imerese.

Public prosecutor Ambrogio Cartosio tells reporters that his office has opened an initial investigation against unknown persons into manslaughter and negligent shipwreck.

As the focus now turns to the manslaughter investigation, here's another reminder of the seven victims of the sinking and the 15 people who survived. 

A close friend of the Lynch family has added to the chorus of tributes for British tech tycoon Mike Lynch, who died in Monday's superyacht sinking.

Susannah Gurdun, who lives in Suffolk, recalled being "daunted" when she first met Mr Lynch at a dinner party, before discovering he was "so much more than the corporate cliche".

"He was riveting.  He was funny, and kind, and endlessly interesting; capable of talking about anything and everything," she said.

Ms Gardun said the businessman also had a "thrilling ability" to make complicated subjects "accessible to those of us less blessed with a science acumen".

"In particular, he was wonderful with children.  I will never forget hearing him explain to a group of them - including our ten year old son - the physics of why the sky went pink at sunset," she said.

She went on describe Mr Lynch as a "true genius" and "phenomenal creative".

Ms Gardun said his daughter Hannah was also showing "serious literary promise", and added that it was "beyond tragic that we will never know where her own particular brilliance might have led".

"I still feel blessed to have shared that time with them in Spain.  Not just because I witnessed Mike’s incredible storytelling; but because I was given a chance of understanding what that moment said about all four of them as a united vibrant loving family," she said.

"He was an extraordinary human being and it was - truly - a privilege to have known him."

A yacht crew member who survived the sinking has paid tribute to Hannah Lynch, calling her a "diamond in a sea of stars".

Sasha Murray, chief stewardess of the Bayesian, has released a statement after divers recovered the final missing body from the wreckage, which is believed to be 18-year-old Hannah.

"Those who knew her will know that Hannah was a diamond in a sea of stars," she said.

"Bright, beautiful and always shining. What most people may not have seen was the extraordinarily strong, deep and loving relationship she shared with her parents, whom she adored more than anything. 

"While swimming with them she often said, if anything ever happened she would save them. 

"I have no doubt that the Irish, Latina fire that burns in her soul kept that spirited determination alive."

Ms Murray's statement comes as a new image of Hannah Lynch and her father Mike Lynch is released:

Prosecutors announced in this morning's news conference that they have opened a manslaughter and negligent shipwreck investigation.

Officials were unable to answer several queries from the media, saying they needed time to establish the facts, but what are the key questions facing prosecutors? 

Why weren't passengers who remained on board the vessel warned about escaping from the yacht?

The prosecutor in charge of the case, Raffaele Cammarano, suggested that some passengers may have been asleep when others were awake.

Asked why they were not woken up or alerted, he said that is something investigators are trying to work out from the statements of the survivors.

He called it an "essential" part of the inquiry.

Why were several of the passengers in one cabin?

The press conference heard several bodies onboard the sunken yacht were found in a single cabin which was not theirs.

Mr Cammarano said investigators currently do not know the reason for them being discovered in the same cabin.

The chief of the Palermo fire service, Bentivoglio Fiandra, said the yacht pinned to the right and suggested people tried to go on the other side, taking refuge in cabins in the higher part of the wreck.

Why did the boat sink?

The vessel had been deemed "unsinkable" by its manufacturer - Italian shipyard Perini Navi.

The Bayesian was hit by a downburst, according to Mr Cammarano, which are powerful winds that descend from a thunderstorm and spread out quickly once they hit the ground.

Officials will look into the safety equipment on the sunken vessel.

Mr Cammarano was asked about whether there is a black box and if the hatches were left open.

He said investigators do not have exact information about the black box and that the first phase of the inquiry will look into it.

Why were nearby vessels not similarly affected?

Another yacht, the Sir Robert BP, was about 150 to 200 metres from the Bayesian when extreme weather hit.

Its crew helped to rescue 15 people from the stricken vessel.

Italian officials said they would be looking at how the downburst could affect one vehicle and not other nearby vessels.

What weather warnings was the Bayesian alerted to?

Maritime director of western Sicily, Rear Admiral Raffaele Macauda, said the weather at the time of the yacht's sinking was abnormal and there was nothing to suggest such an extreme situation would arise.

He said there were forecasts of winds and a storm alert, but there was no warning of a tornado.

"Given that the conditions were such, there wasn't anything to suggest there could be an extreme situation arising," he said.

"There are vessels that can monitor, after all, these events and one would have thought that the captain had taken precautions."

How long will it take to recover the sailing vessel?

Mr Macauda could not confirm how long it would take to retrieve the shipwreck of the sunken yacht.

"Everything depends on the availability of the owners and the timeframe of the retrieval of the wreck and of course all that has to be submitted to the port authorities and in parallel of course there will be the inquiry results and it's only really then that we will be able to authorise the operation," he said.

"I can't say, like some experts who have already spoken on the subject, [said] that it will be eight weeks."

He made clear that the owners will bear the full cost of retrieval, although he could not estimate the figure.

Italian authorities detailed the challenging and meticulous rescue operation to recover the six missing people from the Bayesian wreck (see 9.18am post).

But why was the five-day search so difficult? 

Read more below...

More on this morning's press conference. 

One of the main updates from prosecutors was that they have opened manslaughter and shipwreck investigations after the deaths of seven people in the Bayesian sinking. 

Watch the announcement below...

Prosecutors have given a lengthy news conference this morning on their investigation into the sinking of the Bayesian. 

Read the full report on the prosecutors' probe below...

Marine investigator James Wilkes has been speaking to Sky News after this morning's press conference.

"Naturally, there are more questions than there are substantive answers at the moment - that's the nature of investigative work.

"Something forced that yacht to roll beyond its nominal stability limits, such that it wasn't able to right itself with the ingress of a certain amount of seawater that was coming into the yacht. 

"So the investigators are going to ask themselves one initial question - what must the conditions have been for this to happen? 

"Then they are going to look at the contributing factors to the yacht, sinking, and, and the unfortunate loss of life." 

Prosecutors said this morning that the future of the investigation is reliant on recovering the wreck. 

Mr Wilkes said the yacht is a "major piece of physical evidence in and of itself." 

"It's lying at 50 metres, which is a recoverable depth. 

"If it was significantly deeper, then I'm not sure they'd be considering salvage at this stage or certainly, the salvage question would be a lot more complicated to answer. 

"But if there was the ability to raise that yacht in one piece safely, then it gives the investigators physically more to look at."

Mr Wilkes said he was unsure if the yacht would have a "black box" - called a voyage data recorder in shipping. 

"It would record things like GPS position, heading speed, engine telemetry, whether the radars were on, what they were recording, alarms, communications from the yacht itself, any audio on the bridge.

"But more often than not, these are on merchant ships. The yacht was a commercial yacht in the sense that it could be chartered out so it's quite possible it has a voyage data recorder on, but I'm not sure that it does. I don't know that as a matter of fact," he said.

Be the first to get Breaking News

Install the Sky News app for free

A waterspout may have sunk a luxury yacht. Could this happen in Australia?

ABC Science

Topic: Weather Phenomena

Waterspouts, like this one seen in the Mediterranean in 2018, usually only last a few minutes.  ( Reuters: Alkis Konstantinidis )

On Monday, a sailing yacht off the coast of Italy with 22 people onboard, including British billionaire Mike Lynch, fatally sank . 

Eyewitness reports suggest a waterspout — a large column of water — might have damaged the yacht that was anchored off Sicily. 

Fifteen passengers have been rescued, and six have been confirmed dead, with one person still missing. 

But as rescue efforts continue, an Australian meteorologist says waterspouts, although relatively rare, have damaged property in the past. 

Here's what we know about the meteorological phenomena, and whether we can get them Down Under

What is a waterspout? 

A waterspout is produced by a spinning column of air.

In the water, this phenomenon occurs when cool air passes over warm water, which sucks up water and produces the 'spout' effect.

A similar thing can happen when there's cool air over hot ground, called a landspout, which sucks up dirt. 

While they look similar to tornadoes or cyclones, Rohan Smyth from the Bureau of Meteorology (BOM) says they have some distinct features. 

"Tornadoes come out of a very significant thunderstorm system, whereas waterspouts don't have to be associated with thunderstorms," Mr Smyth says.

"They're quite different." 

Waterspouts are normally short-lived, lasting only a few minutes before petering out. 

However, despite their short life span, they can be exceptionally damaging as winds inside the waterspout can exceed 90 kilometres per hour. 

"Which is what [the BOM] would classify as a damaging wind gust," Mr Smyth says. 

"I wouldn't want to be nearby if I was in a boat."

How common are they? 

Waterspouts can happen "semi-regularly" according to Mr Smyth, although certain conditions have to occur. 

"If you've got a cool air mass and a warm air mass coming together at a head, that can create the conditions to get a circulation going," Mr Smyth said.

While forecasters can predict conditions that might trigger a water spout,  predicting if one will actually occur is "very, very difficult because they are so localised," he adds.

In the latest case, heatwaves had occurred in Italy for the last few weeks, and cooler air had just arrived on Sunday night. 

However, it can't yet be confirmed if it was a waterspout or some other, more common phenomenon that sank the yacht. 

Italian climatologist Luca Mercalli told Reuters the episode could have been a waterspout or a downburst, which is a similar-looking, more common event where rain is quickly dumped into one specific location.

"We don't know which it was because it all happened in the dark in the early hours of the morning, so we have no photographs," he said.

Can they happen in Australia? 

Waterspouts are not just an Italian phenomenon. 

They are seen off the east coast of Australia during autumn and winter as the air gets colder but the water stays warm. 

Earlier this year in March, a series of waterspouts were seen near Moreton Island in Queensland .

And last year boaties in the Whitsundays captured vision of not one but  two waterspouts which formed off Airlie Beach .

However, while conditions in the east are more favourable, Mr Smyth says they can potentially occur anywhere along Australia's coast.

In May this year a water spout was seen near Dunsborough in south-west Western Australia .

Despite this, there are only a few instances of waterspouts damaging boats or other property. 

A tornado that ripped through Lennox Head on the NSW north coast in 2010, destroying homes and causing injuries, actually began as a waterspout.

And in 2019, a waterspout which occurred on the Auckland waterfront in New Zealand toppled a shipping container and damaged a number of yachts. 

Are they getting more frequent? 

While it's unusual to get caught in the path of a waterspout, Mr Smyth says it's not yet possible to say if they are becoming more frequent.

"The classic scientist answer: it depends," he says. 

"Because they're so local scale — so small and so short-lived — it's hard to bring that back to the broader global environment of warming."

Even tracking them down for research can be difficult.

"They're often just metres across and they last a matter of minutes. So unless you get a photo from someone who manages to to catch it, you'll often miss them.

"They're very hard to track even on the radar. You might only get a scan or two before they fall over."

Science in your inbox

Tech magnate missing after luxury superyacht sinks off Sicily in 'violent storm'

A British tech magnate and several other people are missing after a luxury superyacht sank near Sicily’s main city, Palermo, during a violent storm, Italian officials and sources familiar with the matter told CNBC . At least one person was killed.

Mike Lynch, who was regularly described in U.K. media as “Britain’s Bill Gates,” was not among those rescued, said the sources, who asked not to be named because of the sensitivity of the situation. They added that Angela Bacares, Lynch’s wife, had been plucked from the waters off the Italian island.

Lynch was among six people who were unaccounted for, The Associated Press quoted Salvo Cocina of Sicily’s civil protection agency as saying. “They were in the wrong place at the wrong time,” he said. Cocina also confirmed that Bacares had survived.

Italy's coast guard said in a statement that the 184-foot sailboat, named the Bayesian, sank “due to a violent storm” off Palermo at around 5 a.m. local time (11 p.m. ET) with 22 people on board. Fifteen people were rescued, and six passengers were missing, it said.

American, British and Canadian citizens were among the missing, the statement said. The coast guard said in later statement that the ship’s cook had died. It did not give the cook's nationality.  

Karsten Borner, the captain of a ship that rescued the survivors, told reporters that there was a “strong hurricane gust, and we had to start the engine to keep the ship in an angled position,” according to Reuters.

He added that they had “watched the ship behind us not to touch them and we managed to keep the ship in position.” After the storm was over, he said, “we noticed that the ship behind us was gone.”

“Fifteen people inside. Four people were injured, three heavily injured, and we brought them to our ship, he said. “Then we communicated with the coast guard, and after some time, the coast guard came and later picked up injured people.”

One of the survivors, identified as Charlotte Emsley, 35, told the Italian news agency ANSA that she had momentarily lost hold of her 1-year-old daughter, Sofia, in the water but managed to retrieve her and hold her up over the waves until a lifeboat inflated and they were pulled to safety.

“I immediately hugged her again amid the fury of the waves. I held her tight, close to me, while the sea was stormy,” she said. “Many were screaming. Luckily, the lifeboat inflated, and 11 of us managed to get on it.”

The City Council of Bagheria said in a statement that a child of that age was being treated at a children’s hospital. It said that seven adults were taken to the emergency room but that “it seems that none are in serious conditions.” 

Lynch, 59, the missing tech entrepreneur, founded the enterprise software firm Autonomy and became the target of a protracted legal battle with Hewlett-Packard after the U.S. tech giant accused him of inflating the company’s value in an $11 billion sale. Extradited from Britain to the U.S. last year to stand trial, he was acquitted of fraud after a three-month trial.

Italy’s national fire department said in a statement that “divers, a motorboat and a helicopter” had been deployed to help with the search. The wreck was at a depth of around 165 feet, the statement said.  

Divers from the Sicilian city of Sassri and Naples, a city on the Italian mainland , were “arriving on site to search inside the sunken vessel,” it said. 

Built by Italian shipbuilder Perini in 2008, the U.K.-registered Bayesian has an aluminum hull and can carry 12 guests and a crew of up to 10, according to online specialist yacht sites. Online sites list the luxury vessel for charter for up to 195,000 euros (about $215,000) a week, the AP reported.

The boat left the Sicilian port of Milazzo on Wednesday and was last tracked east of Palermo on Sunday evening, with a navigation status of “at anchor,” according to the vessel tracking app Vesselfinder.

Fabio La Bianca, 40, took a picture of the boat at around 10 p.m. local time Sunday shortly after he closed his bar in nearby Santa Flavia. “Absurd tragedy tonight. I am lost for words,” he said Monday on Facebook.

Matteo Moschella is a London-based reporter for NBC News' Social Newsgathering team.

Henry Austin is a senior editor for NBC News Digital based in London.

Advertisement

Supported by

Lynch Yacht Sinking Off Sicily Proves as Baffling as It Is Tragic

As bodies were recovered, the authorities and experts wondered how a $40 million, stable and secure vessel could have sunk so quickly.

• Share full article

By Emma Bubola and Michael J. de la Merced

Emma Bubola reported from Porticello, Italy, and Michael J. de la Merced from London.

Two months after being cleared in a bruising legal battle over fraud charges, the British tech mogul Mike Lynch celebrated his freedom with a cruise. He invited his family, friends and part of his legal team on board his luxury sailing yacht, a majestic 180-foot vessel named Bayesian after the mathematical theorem around which he had built his empire.

On Sunday night, after a tour of the Gulf of Naples, including Capri, and volcanic islands in the Eolian archipelago, the boat anchored half a mile off the Sicilian coast in Porticello, Italy. It chose a stretch of water favored by the Phoenicians thousands of years ago for its protection from the mistral wind and, in more recent times, by the yachts of tech billionaires. The boat was lit “like a Christmas tree,” local residents said, standing out against the full moon.

But about 4 a.m., calamity unfolded. A violent and fast storm hit the area with some of the strongest winds locals said they had ever felt. Fabio Cefalù, a fisherman, said he saw a flare pierce the darkness shortly after 4.

Minutes later, the yacht was underwater. Only dozens of cushions from the boat’s deck and a gigantic radar from its mast floated on the surface of the sea, fishermen said.

In all, 22 people were on board, 15 of whom were rescued. Six bodies — five passengers and the ship’s cook — had been recovered by Thursday afternoon, including that of Mr. Lynch, an Italian government official said, adding that the search was continuing for his daughter.

It was a tragic and mystifying turn of events for Mr. Lynch, 59, who had spent years seeking to clear his name and was finally inaugurating a new chapter in his life. Experts wondered how a $40 million yacht, so robust and stable could have been sunk by a storm near a port within minutes.

“It drives me insane,” said Giovanni Costantino, the chief executive of the Italian Sea Group, which in 2022 bought the company, Perini, that made the Bayesian. “Following all the proper procedures, that boat is unsinkable.”

The aura of misfortune only deepened when it emerged that Stephen Chamberlain, 52, a former vice president of finance for Mr. Lynch’s former company and a co-defendant in the fraud case, was killed two days earlier, when he was hit by a car while jogging near his house in England.

Since June, the two men had been in a jubilant mood. A jury in San Francisco had acquitted both on fraud charges that could have sent them to prison for two decades. There were hugs and tears, and they and their legal teams went for a celebratory dinner party at a restaurant in the city, said Gary S. Lincenberg, a lawyer for Mr. Chamberlain.

The sea excursion was meant as a thank-you by Mr. Lynch to those who had helped him in his legal travails. Among the guests was Christopher J. Morvillo, 59, a scion of a prominent New York family of lawyers who had represented Mr. Lynch for 12 years. He and his wife, Neda, 57, were among the missing.

So, too, was Jonathan Bloomer, 70, a veteran British insurance executive who chaired Morgan Stanley International and the insurer Hiscox.

The body of the ship’s cook, Recaldo Thomas, was recovered. All the other crew members survived. Among them was Leo Eppel, 19, of South Africa, who was on his first yacht voyage working as a deck steward, said a friend, who asked not to be identified.

Since the sinking, the recovery effort and investigation have turned the tiny port town of Porticello, a quiet enclave where older men sit bare-chested on balconies, into what feels like the set of a movie.

Helicopters have flown overhead. Ambulances have sped by with the sirens blaring. The Coast Guard has patrolled the waters off shore, within sight of a cordoned-off dock that had been turned into an emergency headquarters.

On Wednesday afternoon, a church bell tolled after the first body bag was loaded into an ambulance, a crowd watching in silence.

The survivors were sheltering in a sprawling resort near Porticello, with a view of the shipwreck spot, and had so far declined to comment.

Attilio Di Diodato, director of the Italian Air Force’s Center for Aerospace Meteorology and Climatology, said that the yacht had most likely been hit by a fierce “down burst” — when air generated within a thunderstorm descends rapidly — or by a waterspout , similar to a tornado over water.

He added that his agency had put out rough-sea warnings the previous evening, alerting sailors about storms and strong winds. Locals said the winds “felt like an earthquake.”

Mr. Costantino, the boat executive, said the yacht had been specifically designed for having a tall mast — the second-tallest aluminum mast in the world. He said the Bayesian was an extremely safe and secure boat that could list even to 75 degrees without capsizing.

But he said that if some of the hatches on the side and in the stern, or some of the deck doors, had been open, the boat could have taken on water and sunk. Standard procedure in such storms, he said, is to switch on the engine, lift the anchor and turn the boat into the wind, lowering the keel for extra stability, closing doors and gathering the guests in the main hall inside the deck.

12 guests occupied the yacht’s six cabins. There were also 10 crew members.

Open hatches, doors and cabin windows could have let in water during a storm, according to the manufacturer.

Open hatches, doors and

cabin windows could

have let in water

during a storm,

according to the

manufacturer.

Source: Superyacht Times, YachtCharterFleet, MarineTraffic

By Veronica Penney

The New York Times attempted to reach the captain, James Cutfield, who had survived, for comment through social media, his brother and the management company of the yacht (which did not hire the crew), but did not make contact.

So far none of the surviving crew members have made a public statement about what happened that night.

Fabio Genco, the director of Palermo’s emergency services, who treated some of the survivors, said that the victims had recounted feeling as if the boat was being lifted, then suddenly dropped, with objects from the cabins falling on them.

The Italian Coast Guard said it had deployed a remotely operated vehicle that can prowl underwater for up to seven hours at a depth of more than 980 feet and record videos and images that they hoped would help them reconstruct the dynamics of the sinking. Such devices were used during the search and rescue operations of the Titan vessel that is believed to have imploded last summer near the wreckage of the Titanic.

After rescuers broke inside the yacht, they struggled to navigate the ropes and many pieces of furniture cluttering the vessel, said Luca Cari, a spokesman for Italy’s national firefighter corps.

Finally, as of Thursday morning, they had managed to retrieve all but one of the missing bodies, and hopes of finding the missing person alive were thin. “Can a human being be underwater for two days?” Mr. Cari asked.

What was certain was that Mr. Lynch’s death was yet another cruel twist of fate for a man who had spent years seeking to clear his name.

He earned a fortune in technology and was nicknamed Britain’s Bill Gates. But for more than a decade, he had been treated as anything but a respected tech leader.

He was accused by Hewlett-Packard, the American technological pioneer that had bought his software company, Autonomy, for $11 billion, of misleading it about his company’s worth. (Hewlett-Packard wrote down the value of the transaction by about $8.8 billion, and critics called it one of the worst deals of all time .) He had been increasingly shunned by the British establishment that he sought to break into after growing up working-class outside London.

He was extradited to San Francisco to face criminal charges, and confined to house arrest and 24-hour surveillance on his dime. In a townhouse in the Pacific Heights neighborhood — with security people he jokingly told associates were his “roommates” — he spent his mornings talking with researchers whom he funded personally on new applications for artificial intelligence. Afterward, he devoted hours to discussing legal strategy with his team.

Despite his persistent claims of innocence, even those close to Mr. Lynch had believed his odds of victory were slim. Autonomy’s chief financial officer, Sushovan Hussain, was convicted in 2018 of similar fraud charges and spent five years in prison.

During Mr. Lynch’s house arrest, his brother and mother died. His wife, Angela Bacares, frequently flew over from England, and she became a constant presence in the San Francisco courtroom during the trial.

After he was finally acquitted, Mr. Lynch had his eye on the future. “I am looking forward to returning to the U.K. and getting back to what I love most: my family and innovating in my field,” he said.

Elisabetta Povoledo contributed reporting from Pallanza, Italy.

Emma Bubola is a Times reporter based in Rome. More about Emma Bubola

Michael J. de la Merced has covered global business and finance news for The Times since 2006. More about Michael J. de la Merced