Re: [Paddlewise] Initial Stability, Rolling and Seaworthiness

From: <LedJube_at_aol.com>
Date: Wed, 8 Mar 2000 09:24:05 EST
In a message dated 3/8/00 10:00:43 AM, rebyl_kayak_at_hotmail.com writes:

<<Is it true that boats which have higher initial stability are not 
necessarily as stable in rough seas? Also can anyone tell me of 
circumstances when a roll, or reenter and roll is not the best method of 
self rescue in a hardshell?
     Various sources have suggested that for hardshells a shorter, heavier 
(15ft & 26kg) boat with a V chine and relatively low initial stability might 
be more suitable in roughish seas than lighter longer boats with greater 
initial stability (17ft & 22kg). I think one of the arguments goes that it 
is easier with the V chine to knee lift the boat horizontal when a wave is 
coming at a steep angle.          Have I got the concepts right?>>

    Others on this list can provide better scientific arguments but I'll toss 
out my own anecdotal evidence. Initial stability which makes the boat feel 
steady on flat water also causes it to track the surface contours during 
excited seas. Which is to say that a boat that it will be tossed around by 
the same stability as the waves steepen. Boats with low initial stability 
have a much reduced righting moment and hence are little affected by the wave 
action. The V shape hull is more about tracking than stability, a rounded 
hull can be equally seaworthy but may track less strongly.
Low initial stability boats are no harder to handle in rough water than they 
are in flat water. They are equally unstable in both conditions. High initial 
stability boats are at their best in flat water and become more difficult to 
handle as the conditions deteriorate.
    Shorter boats turn faster as a general rule and hence are easier to 
handle in rough water but there is a tradeoff in that the shorter length 
makes them more sensitive to wave action along the boats length and short can 
also mean slower to some extent.
    You are basically right about the knee lift versus steep waves as long as 
you substitute "lower initial stability" for "V chine".
    I've heard people argue the heavy versus light argument but for me it's 
more about sail area versus inertial. They argue that a heavier boat will be 
less affected by beam winds as the bow or stern rises out of the water. I 
believe that low windage is a better way to control this effect.
    I know of no condition where are roll is not the preferred self rescue 
but if for some reason it is not possible a reenter and roll would be my 
second choice followed by the assisted "T" rescue then lastly a paddlefloat 
reentry.

Best of luck!

Jed

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Received on Wed Mar 08 2000 - 06:24:28 PST

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