[PCW] Hull design

[bill]

Jim wrote,

"Since most of the discussion on hull design centers
around long and 
narrow - why not a hull design where below the water
line the hull 
meets that requirement but above the water line it is
flared wider to 
give greater design livability.
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I realize this would not make much difference under
heavy weather 
conditions, but most of us tend to stay out of heavy
weather if we 
can. There may be other issues but this was just a
thought."

You can see this 'expanded hull above the wl' concept
in several sailing multihull designs.  The corsair
(Farrier) trimarans, Chris White's Hammerhead 54 tri,
there are others.  It's especially prevalent in some
sailing tris as the center hull contains most (all) of
the living accomodations and there's not much there
unless you flare the hull.

The downside is too much "expansion" which will cause
slapping or pounding.

Malcolm Tennant's trademark powercat hullform employs
a similar feature with the pronounced knuckle above
the lwl.  This provides a skinny hull in the water
with reserve bouyacy when the knuckle is immersed, a
spray deflector, and an increase in interior volume
above the knuckle for accomodations.

Downside is similar; too much knuckle can slap or
pound, and probably the transition fron hull through
the knuckle to topsides is important.  If it's an easy
transition, noise and motion will be easier.


Bill




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