Subject: [harryproa] Re: wtw vs tri
From: "Robert" <cateran1949@yahoo.co.uk>
Date: 5/21/2008, 9:18 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

-It would be more common to have the waves at 45degrees In this case,
the Harry is much less racked than a tri. Contrast 45 degrees with the
wavelength about the same as the main hull of the tri with a HArry
with the same length ww hull boat with steep waves. If you do the same
diagram on a tri with same ww hull length at all different angles and
lengths of swells, I reckon there would be more places that give
racking loads and the bows will be further away from the crossbeam on
the main hull compared with the proa ww hull. Also the tri hull will
be heavier.

...> wrote:
>
> Look in photo's nonharry of what i'm tring to get at.
>
> Todd
>
>
> --- In harryproa@yahoogroups.com.au, "Robert" <cateran1949@>
> wrote:
> >
> > FOr some reason I have been closed out of the proa group. This is
> in
> > reply to a post of Todd's on that list.
> > Todd, I am not sure about what you are saying, but I am saying
> something
> > that I think is relevant.
> > AS far as I can see the ww hull on a tri is acting as extra wtw,
> but
> > also lots of drag and it bounces around and occasionally collects
> > waves when going to ww in steep chop. The different lengths on a
> wtw
> > proa should damp oscillations, especially with high prismatic
> > coefficient and damping waterplane at the ends. There should be
> less
> > strain on the crossbeams for the same length as the bows don't
> have to
> > fight so much in meeting waves, and the crossbeams are closer to
> the
> > ww hull ends on a wtw proa. I suspect that the loads on the
> crossbeams
> > would be similar to the loads on a tri hull with similar weight and
> > length to the ww hull. The wtw proa allows a much longer bow to lw,
> > something a tri can't do as well as it would mean the ww float
> would
> > be ridiculous, picking up waves and wind.
> > Having a shorter ww hull on an Atlantic proa would work,especially
> as
> > it brings the line through the center of effort for the rig well
> > forward, but you have the problem of getting caught aback. I had an
> > idea of a tri proa, with rig in shorter hull to ww, and a smaller
> > outrigger to ww again, to allow safe sheeting for getting caught
> > aback. It makes sense for round the bouys racing, but would be a
> > hassle for cruising
> > Roert-- In proa_file@yahoogroups.com, "tsstproa" <bitme1234@>
> wrote:
> > >
> > > --- In proa_file@yahoogroups.com, "tsstproa" <bitme1234@> wrote:
> > > >
> > > > If rig position having it centered, upwind, or downwind doesn't
> > > > matter. Which I think it does!
> > > >
> > > > How is it that Wtw would be at a disadvantage compared to a wtL
> > > proa?
> > > >
> > > > How is it then that tris can support entire windward side of
> boat
> > > > including main hull on only one float to leeward. And due most
> of
> > > > there sailing in a somewhat Wtw configuration.
> > >
> > > (I meant Wtw proa not Wtl below sorry)
> > > > In a Wtl short hull to windward configured proa. Is it not
> > > possible
> > > > to achieve leeward bow to windward stern stability due to the
> > > > windward hulls shortness compared to leeward hull? Unlike that
> of
> > > a
> > > > tri. Does this in fact cause the instability? In the wrong
> seaway
> > > > could it self perpetuate oscillations due to the uneven ends,
> beam
> > > > width or due to not having a dampner out to windward like tri
> > > > possibly causing self destruction? Can these loads be
> calculated
> > > and
> > > > then built light enough for feasible use on such a boat? How
> much
> > > > real structual engineering tests have been done and under what
> > > > strains or stresses?
> > > >
> > > > Todd
> > > >
> > >
> >
>

__._,_.___
Y!7 Toolbar

Get it Free!

easy 1-click access

to your groups.

Yahoo!7 Groups

Start a group

in 3 easy steps.

Connect with others.

.

__,_._,___