Yacht Stability

[shiggs]

Hi, I am a 3rd year student at Plymouth University studying Navigation and Maritime Science.
I am starting research into my honours project in which I am looking at yacht owners attitudes towards stability. I am focusing on three particular vessels, a Laser dinghy, Dufour 445 and a Nordhavn 55. I will be conducting an inclining experiment on the Dufour 445.
I would really appreciate if anyone has any information about the stability of these vessels or owns one and knows what information was given to them when they bought the boat.
Your help would be much appreciated!

 

[Georgio]

Why did you choose those particular boats? I would have thought you would get more interesting results if you compare something like a Contessa 32 (that is known to have a very high AVS but lower form stability) against say a trailer-sailer with a lifting keel (and or water-ballast) that may have a great deal of form-stability but a low AVS.

Can't quite see how a laser dinghy relates to your project, different type of craft for a different type of sailing...

Sorry, not trying to ne negative, perhaps I don't grasp what you are trying to achieve or prove.

 

[sarabande]

stability curves for the keelboats will doubtless be available from the naval architects, but it may be difficult to prise them out of their hands as it is professional info.

An empirical stability test is going to have many more degrees of freedom, and then becomes subjective.


What are you trying to find out ? Whether owners engage with stab curves as part of the buying process; whether stab curves influence the enjoyment; whether stab curves direct a buyer towards a type of boat ? Lots of areas, but to help, we need to have more, and clearer, details of your objectives.

 

[Neil_Y]

More information needed of what you are looking for as Sarabande said.

There are two types of stability that concern sailors (well me at least), how stiff the boat is, which is a guide to how much canvas she will carry (and her motion) and the angle of vanishing stability which is an indication of what might happen in extremes of weather such as being rolled. It's something I looked at and what put me off some designs.

The Laser shouldn't be there as no body buys a racing dinghy based on its stability, dinghies (without a ballasted keel) do not need stability as the movement of ballast in the form of the sailor is what keeps them the right way up.

An interesting question is which boats people think are more stable because of the look/type and what is in practice. There's enough for a phd there but it's probably more psychology than marine science.

 

[lpdsn]

Hi, I am a 3rd year student at Plymouth University studying Navigation and Maritime Science.
I am starting research into my honours project in which I am looking at yacht owners attitudes towards stability. I am focusing on three particular vessels, a Laser dinghy, Dufour 445 and a Nordhavn 55. I will be conducting an inclining experiment on the Dufour 445.
I would really appreciate if anyone has any information about the stability of these vessels or owns one and knows what information was given to them when they bought the boat.
Your help would be much appreciated!

If you want technical data there's lots of information on the RYA website in the technical section. Also worth talking to RORC as they gather a lot of data for IRC handicaps and for stability screening for offshore races.

Or is it a survey of opinions or attitudes you want?

 

[BrianH]

As others have commented the Laser just doesn't fit a stability project. I used to race one on the Swiss lakes as a diversion to my yacht in the Adriatic, and they have little if any inherent stability, relying solely on the crew's counterweight to keep them upright. Temporarily tethering to shore required a constant eye for a gust that could just blow them over.

 

[onesea]

Sounds to me like the OP has chosen vessels he has access to in some way or another.

Laser as all have said very little stability what there is is by form... Owners do not care unless it makes them go faster.
Dufour Cruising Sailboat boat... I am sure attitudes to stability, will vary hugely among owners.
Nordhaven Motorboat if not of the Sunseeker type. Again I am sure attitudes to stability, will vary hugely among owners.

Would be quite interesting to see how significant good and bad stowage and gear loading makes on the last two.

With he MOBO you would not want too much stability it could make her horribly uncomfortable.

 

[[70521]]

Interesting project. Can you define, "yacht owners attitudes towards stability" in this context asks grumpy old engineer? Are you specifically looking at sailing vessels? Having had a tour of Princess Yachts last week, and very interesting it was too, it might be iteresting to get the veiw of some motor yacht owners.

Having had a really good look at a Boreal this summer it might be worth contacting them as they have some interesting ideas about stability that I've not seen in any other sailing vessel.