Please select your home edition
Doyle Sails 2020 - Redefining Boundaries 728x90 TOP

Global Solo Challenge - Can yachts capsize in mountainous seas and high winds?

by Dave Proctor 31 May 00:13 PDT
Can yachts capsize? © Global Solo Challenge

When researching the attributes of the yachts entered into the Global Solo Challenge (GSC) and the possibility of them capsizing and whether they would self-right, one of the first pieces of advice I found was, that you should not go sailing in inclement weather, particularly when there are high winds and large waves.

Now I am sure the skippers on the GSC will be keen to heed this advice, but something tells me that, as they sail their way around the world, they may encounter some pretty horrible conditions. Let's try to break down this topic in very simple terms and language.

To understand whether a yacht will capsize and self-right it is firstly important to understand some of the basic physics involved.

What stops a yacht from capsizing in 'normal' conditions is that a yacht has a keel to keep it upright and also provide lateral resistance to stop the boat drifting sideways in the water. The keel contains ballast which gives the boat a lower centre of gravity.

Now you would expect to see any sailing boat heeling over in a reasonable wind, but what you should also be aware of is that as the boat heels the pressure on the sail decreases. A simple experiment to show this effect is, that if you were to take a sheet of plywood and hold it vertically with the wind on the main area, you will feel the force of the wind. If you then leant the board backwards at 45% the wind pressure would be a lot less.

Also, when a boat is heeled over, the ballast in the lowest part of the boat exerts more downward force. An experiment to show this would be if you were to grab a weight in your hand with your arm extended downwards you would feel the gravitational pull. If you were to hold your arm straight out in front of you, still holding that weight, then there would be a lot greater force on your arm pulling the weight down.

So as the boat heels over, there is less pressure for it to continue to fall into the water and more pressure for it to return to upright.

Now, without going too deep into the dynamics of yacht design, all boats will have an individual Angle of Vanishing Stability (AVS). This is the angle beyond which a boat will not self-right.

Because of the low centre of gravity and design, an ocean-going yacht would be expected to have an AVS of between 130 and 140 degrees from vertical.

Now that means, the mast of a yacht could be pointing downward into the sea between 4 and 5 o'clock, and the boat would still self-right to a vertical position. When a boat heels to 90 degrees and puts the mast in the water without capsizing we call this a knock-down.

If the boat goes beyond this point, then the yacht will invert and with no other movement become stable in the upside-down position.

However, a boat will often capsize in rough conditions, and if a wave were to rock the boat so that the angle of the boat goes below the AVS then the boat will again self-right. Very often, but not always, the mast snaps during the 360 roll.

In the case of a capsize, a major problem that can occur, aside from the likely dismasting, is water flooding the hull and the boat could partially or totally sink. This is why the organisers of the GSC have specified that the partaking yachts must have waterproof sectional bulkheads, so that any boat that does capsize, will not become totally flooded and sink.

This is a very brief article on a highly complex issue, but I am sure you agree that it shows why sailing boats can perform as they do and why a capsize, with the loss of a boat, during the GSC, will hopefully be an unlikely event which however skippers need to prepare for.

You can read more about watertight bulheads on this page and you can refer to a very interesting article by Proboat. On the topic of stability you will find very detailed information in this article by Marine Marsh Design and I recommend the reading of this article by Gerr Marine.

Related Articles

Global Solo Challenge: Solo offshore yacht racing?
The first solo race across an ocean was held as late as 1960 When sailing single-handed for extended periods, the greatest problem was, in the past, who was going to helm and keep watch when the skipper had to sleep? Posted on 21 Jun
Global Solo Challenge: Doldrums, pot au noir, ITCZ
Today we will look at the first hurdle the participants will find on their way One thing about the Global Solo Challenge is for sure: both the skippers and the boats will be facing huge challenges during their circumnavigation. Posted on 18 Jun
Which boat would you pick to sail round the world?
Global Solo Challenge opens up the opportunity The unique format of the Global Solo Challenge opens to the opportunity of sailing around the world in an organised event on a wide range of boats, with little limitation imposed by the rules. Posted on 14 Jun
Which boats were designed by Frers?
Several Global Solo Challenge yachts designed by the Argentinian firm Amongst entries for the Global Solo Challenge (GSC), one firm of Naval architects stands out, particularly for the number of yachts entered, which were designed by Argentinian firm Germán Frers (pronounced with a soft Spanish G, so it sounds like Herman). Posted on 8 Jun
Global Solo Challenge - Do you qualify?
There must be thousands of sailors who dream of sailing around the world, non-stop and alone There must be thousands of sailors worldwide who dream of sailing around the world, non-stop and alone. Just you and your boat overcoming the elements and achieving one of the pinnacles of yachting aspiration. Posted on 6 Jun
Sailing past the Cape Verde archipelago
Global Solo Challenge will metaphorically 'leave the old world' here Almost 2000 miles into the circumnavigation, having left A Coruña and passed the Iberian Peninsula, the Canary Islands, and the coast of Mauritania, the skippers of the Global Solo Challenge will metaphorically “leave the old world”. Posted on 3 Jun
Which boats were designed by Sparkman & Stephens?
Global Solo Challenge skipper Daffyd Hughes will be sailing an S&S 34 One of the smallest yachts in the fleet that will set off on the circumnavigation next year. This yacht is only 34 feet in length, but it was designed by the great designer Olin Stephens of the American Company Sparkman & Stephens. Posted on 25 May
Global Solo Challenge welcomes 49th entry
The planets have aligned for Stéphane Girolata and he now wants his dream to come true Stéphane has discovered the sea and sailing almost by chance, whilst runinng a mushroom farming business he wanted to get a boating licence to reach out to new potential clients anchored in the bay of Saint-Tropez. Posted on 25 May
Global Solo Challenge welcomes 48th entry
Gardner LaMaurice was already in the process of preparing his boat to complete a circumnavigation With his entry the young American wants to break the stereotype of sailing only being accessible to rich retired people and hopes to inspire others to follow his example. Posted on 18 May
The coast of Mauritania and the threat of piracy
Even though pirates are known to mainly target cargo ships, attacks on yachts are not unheard of Following winds... a favourable current... the sea helps the skippers move faster… Some sections of the Global Solo Challenge will be pure bliss for its participants. Posted on 17 May
Sea Sure 2021 - FLO - FOOTERLloyd Stevenson Catalyst 45 728x90px3 BOTTOMCoast Guard Foundation FOOTER 1