Re: [Paddlewise] Stability

At 07:22 AM 5/12/2005, John Winters wrote:
>Nick wrote;
>
>>  Primary stability has almost nothing to do with the cross sectional
>>shape of a boat. Chines, no chines, makes no difference. It is the
>>shape of the water plane and the height of the center of gravity that
>>will determine initial stability.
>
>Hmmm. Out of curiosity I drew two boats with the same displacement, same 
>CG and same waterline area and shape. One had a "V" bottom and one a flat 
>bottom. The flat bottom boat had a righting arm at 5 degrees 38% greater 
>than the "V" bottom boat. That seems like a lot of effect. Granted this is 
>an extreme example.
>
>Maybe what Nick means is that, given two similarly shaped boats,  having a 
>chine or no chine does not produce a significant difference. Am I reading 
>you wrong on this, Nick?

Doesn't the "shape of the water plane" account for the differences you're 
seeing?  Maybe I'm missing what "shape of the water plane" means.

I also assume that "height of center gravity" is in relation to center of 
buoyancy (yes, I've read Nicks excellent stability article).  Would the 
center of buoyancy change for differently shaped bottoms?   Having paddled 
lots of different boats with different hull shapes I've noticed a different 
"feel" in the initial stability in different.  Boats with very flat hull 
feel very resistant to tipping.  Boats with a shallow V have a gentle 
rocking feel. Boats with a deeper V start to feel "twitchy",  Rounded hull 
boats feel "slippery" (sort of like sitting on a basketball).  That's not 
very scientific but that's just how different shaped hulls *feel* to me.
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