41085Re: Sharpie Cat design
- Dec 11, 2004The cabin is neat. Kinda Birdwatcher flexible utility. Ok for semi-
What about individual hull static WLLength/WLBeam ratio? Maybe ~
18'/23"? Giving approx 9.3? Too high?
Wharram's Design book says his first Atlantic crossing catamaran,
Tangaroa, was 23'6". It says the defects were: it had a flat bottom
which pounded ( Bolger says sharpiecat would be rather noisy), its
8/1 individual hull L/B dragged a displacement wave,
and its full
bows gave a slow hull speed. (also after this cat he adopted as one
of his design principles: No permanent deck cabin between hulls.)
IIRC JW states elsewhere superstructure height should be 11% (no
more than 15 percent) of length, or windage will be too much.
Wharram's trailerable 16' Maui design (now not marketed due to newer
stitch and tape stringerless construction methods superseding) has
the option of a solid ply bridgedeck. I gave a lot of thought to
somehow adding spartan accommodation - in the hulls by raising
topsides but leaving an open bridge deck, or by walling in the
bridge deck something like Bolger's Fishcat with a tent top, and so
on. The 60 degree V hulls, displacement, deck clearance and
seaworthiness made it too difficult for me.
However a simple trailable catamaran, easily (= quickly) rigged and
launched at the boatramp, with some spartan accomodation (not a
tent) for one or two, yet with acceptable performance remains an
Could Sharpiecat be reduced to a trailable beam (Sail area may need
complementary reduction/lowering), or could the bridgedeck/cabin be
fastened down over raised hull coamings in an easily demountable
way? To trailer it dissassembled put the cabin, rotated 90 degrees,
on top of the hulls.
--- In email@example.com, "Todd" <ktsrfer@m...> wrote:
> The cabin is the kicker on this cat . Seems you can't have your
> and eat it to. Start optimising the cabin for windage you end up
> with making the hulls taller to acommadate space lost in cabin
> adds windage. The cat just looks fun . But I keep seeing 2 skinny
> hulls one short and a one long with a big square cabin in the
> middle;) I'll keep you posted.
> --- In firstname.lastname@example.org, "doug6949" <prototype@c...> wrote:
> > Windage is always going to be a factor to consider in catamaran
> > pontoon designs. Any cabin you put on it will significantly
> > the profile.
> > 18" freeboard is not much for a 23 foot cat. Your cabin profile
> > what you need to evaluate.
> > Doug
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