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Vastbinder 09-10-2004 01:43 PM

Construction/stability wings
 
This is nothing I''m currently building, just a thought I''ve been mulling over.

Out-rigger canoes have the long side poles attached to either one or two "floats" to add stability.

Could one build a sailboat using similar design features? (though, really I''m thinking of shorter, more rubust "wings")

I would think this would add alot to the stability, and other than being a little unwieldy, I don''t see too many downsides unless it''d be a structural stress issue.

Jeff_H 09-11-2004 07:04 AM

Construction/stability wings
 
Floats (Amas) are added either side of narrow easily driven sailboats fairly routinely and called a Trimarran. Quite a bit rarer is the case where an ama is added to just one side which is called a Proa. There are Atlantic and Pacific proas, which are determined by whether the ama is located to leeward or to windward of the main hull. Pacific Proas have their amas to windward which gives a higher performance accompanied by a higher risk of capsize. Here is a link to a 20 foot Pacific style Proa. http://www.clcboats.com/boats/pacificproa.php/cart_id=6eae13a26785b98d43a93973598417e3/

Respectfully,
Jeff

Vastbinder 09-13-2004 08:56 AM

Construction/stability wings
 
This might be an immensely stupid question...

but I would assume that the trimarran type design (though I hadn''t thought of anything quite that wide) would add stability, wouldn''t it?

Jeff_H 09-13-2004 09:21 PM

Construction/stability wings
 
There are a variety of types of stability but except for dynamic stability, they all derive from the horizontal athwartships distance between the center of gravity of the boat and the center of bouyancy of the boat in the heeled position. In the case of a trimarran the leeward ama moves the heeled center of buoyancy outboard at a rapid rate generating a lot of stability. This type of stability is called ''form stability''. Form stability allows a lot more stability at small angles of heel for any given weight of craft, but it comes at a price in terms of more rapid and therefore less comfortable motion, and also as the heel angle increases above comparatively small angles stability decreases rapidly and the likelihood of a capsize increases. Once inverted a high form stability boat is likely to be extremely difficult to right again.

Jeff

Vastbinder 09-16-2004 11:24 AM

Construction/stability wings
 
OK, so a trimarran type craft, while extremely stable and hard to capsize, gives a rough ride and if it does start to tip, once it passes such and such point is going to tip and be difficult to right.

I see.


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