Re: [Paddlewise] paddlefloat photo

From: "Peter Rathmann" <prathman_at_attbi.com>

> water movement, but that is also a question of design details.  If you
> believe that a properly fitted sea sock could add to stability in a
> flooded boat, then similarly fitted internal
> sponsons/bulkheads/'whatever you want to call them' can certainly do the
> same thing. As you said before, the water can't tell the difference.

I wouldn't say that it adds to stability.  It minimizes the reduction of stability.
That may sound like semantics, but I don't think so.

In general, what you say is true, however, I've been thinking in terms of the 
sponsons that I've been seeing in real kayaks.  These tend to be small.  

I think there's been a difference in perspective between me and others, including
yourself.  I've been taking a sort-of pragmatic, "is it good enough?" view considering
kayaks I've seen or paddled, whereas others have been saying "does it happen at
all?" with atypical or theoretical kayaks.   We have both come to different conclusions, 
but to different questions.   In the context of the original discussion, I may be off base.

In terms of "good enough", sponsons in real kayaks contribute to reserve flotation,
not stability.

Minimizing the amount of water in the cockpit is a good thing.  That's one 
reason I've replaced the forward bulkhead in my Solstice to one that
is further aft.  However, the water remains a destabilizing effect.  Whether you
remove the volume forward or laterally, you still improve the situation.  I'm
not ready to say that it's enough to make an unstable kayak stable.  I've paddled
kayaks with negligible reserve stability with only a couple of inches of water
inside and both fore and aft compartments empty.  In a kayak like that,
a sponson or any other trick would have little effect at all.

The main reason I moved my Solstice's bulkhead, however, was to reduce the 
amount of water I'd have to pump and give myself more dry storage forward.  
My tests since then have confirmed that it doesn't yeild a significant 
improvement in retaining stability.

I can't imagine taking my Ellesmere and adding internal flotation that would
have a great effect.  There's little room between the seat and the hull on the
sides.  I could take up volume around my legs, but it would have to be 
planned with ease of entry and exit in mind.  In the end I doubt that a 
significant improvement in flooded stability would be there.  An improvement,
but not significant enough for me to bother.  If you're talking about a kayak
with a 28 inch beam, that would be different, but that's not a typical kayak.

Mike



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