Do larger yachts self right?
May 27, 2009 in
Yacht Charters
The larger sailing yachts self right if they capsize, about 30-40ft ish
What safety equipment would be a good idea? i know about life jackets ect.
just thinking would a vhf be a good idea for races?
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5 comments
Oliver Shaw on May 27, 2009 at 3:22 pm
Yes, they will normally self-right. BUT …
You need to consider not merely the 90-degree knock down, but the risk of inversion. Here it becomes a little more complex.
For every yacht there is some angle, known as the angle of vanishing stability, at which the righting moment becomes zero. If capsized beyond that angle she will invert, and once inverted she will tend to remain inverted.
What that angle is, and the shape of the stability curve over the full 360 degrees, depends on the particular hull form and on the ballast and on how the weight is distributed in the boat. Ideally it will be much larger than 90 degrees, i.e. the hull will have to be well on its way to inversion before losing its righting moment, but it varies considerably between different hull forms, and there are even some hull forms where it is less than 90 degrees.
For example, shallow but beamy hulls are often initially very stiff, but once knocked down they can invert comparatively easily. A narrower hull may well be initially more tender, even if she has a deep draught and a lot of ballast at the bottom of the keel, but she will often be far less likely to invert.
As a PS to my original answer, I see that Tony C states that " I've not heard of a monohull remaining inverted under any conditions, there's always enough movement to bring the boat back up. ". One well-known example where this did happen was Tony Bullimore's inversion in the 1996 Vendee Globe race. This is not however the only case.
Your remaining two questions will take too long to answer properly here, although I would say that harnesses and lifelines are in my view even more important in a yacht than lifejackets. VHF should be considered not just a good idea, but essential, plus longer range radio if you expect to sail more than about 25 miles offshore, plus a vast amount else in the way of safety equipment. However you specifically mention racing; you will not normally be allowed to make transmissions while actually racing, but it is still a very important piece of safety equipment.
Reading between the lines it appears (in the nicest possible way) that you are a beginner and that you may be thinking of taking a yacht offshore. While offering you every encouragement, could I therefore urge you as strongly as I possibly can to either get a lot of experience sailing as crew under an experienced skipper, or alternatively take a proper course of instruction – both practical and theory – to RYA Yachtmaster or similar qualification (in the UK), or whatever is available if you live elsewhere than the UK.
What you will learn that way will amply cover all three of your questions, and much more. Yacht sailing, whether cruising or racing, is a marvellous sport, and one that I hope you will enjoy, but it can all too easily become a lethal one when practised by beginners who try to go beyond their knowledge and skill level. The solution to that is training, by whatever means you obtain it.
And the training itself should be enjoyable, as well as rewarding.
Get properly trained, and then enjoy!!
Orion on May 27, 2009 at 3:22 pm
Yes, and much larger ones. Boat design is an act of balancing several features to get the best of all. Stability (measures by capsize formula and angle), motion comfort, and righting formula.
Most racing boats are required to meet the racing authorities formulas that include a righting requirement. Good example is the Vendee Globe race going on now. 70m boats that will right self. Problem with the formula in 1990 lead to several lost boats in 1996.
For safety equipment check out link below.
werepoodle on May 27, 2009 at 3:22 pm
Most keel boats are self righting. The keel is heavy enough to pull the boat upright should it capsize. In single handed offshore races, it is sometimes required that the boat demonstrate that it is self righting.
Safety equipment is not just a good idea, it's usually required by law. The minimum safety equiment is dictated by the size of the boat. The larger the boat, the more safety equipment is required. See the source links below. If you live outside Canada and the US, contact your appropriate government agency.
VHF is a good idea to have anytime you are on the water, not just for races. If you have a problem, it allows you to get help sooner. If others are having problems, it allows you to help.
Tony C on May 27, 2009 at 3:22 pm
All largish monohull yachts have something called a GZ curve calculated for them. This shows the "righting moment" or the force that's trying to right the boat at all angles of heel. It shows the interaction between the centre of buoyancy and it's centre of gravity. All yachts will invert at some critical angle (usually around 130 degrees from the vertical) but a yacht that's rolled usually has enough momentum to roll right over and come upright again. In any case, it's extremely difficult to roll a yacht with sails up past 90 degrees. This is because the sails trap air as they hit the sea. I've not heard of a monohull remaining inverted under any conditions, there's always enough movement to bring the boat back up. A multihull, on the other hand, remains inverted very easily. In fact they're more stable inverted than they are upright!
aclrfp on May 27, 2009 at 3:22 pm
The definition of capsize is when the mast touches the water (roughly a ninety degree angle). A little sixteen foot ComPac will self right. Of course self righting needs a weighted keel. So this means that most multiple hull boats will not self right.