Hi Rob & al

Just a thought. Some time ago you posted description and photos of the
techniques you used to build a carbon fibre mast for Visionarry (IIRC).
Would it be possible to use the same technique, or some variation, to
build the beams? Or is this simply overkill, particularly for the
smaller designs? Or is what you are doing already easier and simpler?

Enjoy

Jim Baltaxe
ITS Desktop Support
Victoria University of Wellington
NEW ZEALAND
(04) 463 5018 or 027 428 4648


Klein bottle for rent. Inquire within.
"If we knew what we were doing, it wouldn't be called research, would
it?" -- Albert Einstein



> -----Original Message-----
> From: Robert [mailto:cateran1949@...]
> Sent: Friday, 9 July 2004 2:33
> To: harryproa@...
> Subject: [harryproa] Re: Beams to windward hull
>
> G'day,
> Interesting to see how you telescope these beam. A bit of
> graphite in the topcoat of the internal radii?
> Robert
>
>
> --- In harryproa@..., "Rob Denney" <proa@i...> wrote:
> > G'day,
> > Beams will be V The lower rod needs to line up with the bulkhead
> that supports the mast, plus it needs to deflect water downward in
> both directions. The netting attachment is pretty simple, as it is
> contained in a frame. Pictures will be on the web in the next month,
> all going well.
> >
> > regards,
> >
> > Rob
> > ----- Original Message -----
> > From: Tony Richardson
> > To: harryproa@...
> > Sent: Thursday, July 08, 2004 9:14 AM
> > Subject: Re: [harryproa] Re: Beams to windward hull
> >
> >
> > A pultruded carbon rod at each edge would handle the loads
> admirably.
> > Fill the area between the rods with foam and it would be very
> strong indeed
> > Attaching netting might be a bit tricky but no harder than other
> boats.
> > Mark which way will the beams be oriented /\ or \/ or > or <?
> > Rgs
> > Tony
> > ----- Original Message -----
> > From: proaconstrictor
> > To: harryproa@...
> > Sent: Thursday, July 08, 2004 2:12 AM
> > Subject: [harryproa] Re: Beams to windward hull
> >
> >
> >
> > >
> > >
> > > Proaconstrictor wrote
> > >
> > >
> > > I think the basic concept with the triangular beam is to
> come
> > up with
> > > an I-joist type truss that will carry the major loads in
> the
> > vertical
> > > plane, then box it out with skins so it looks better, is
> more
> > aero,
> > > and of course picks up loads of strength when the loads
> aren't
> > > vertical.
> > >
> > > Therefore adding weight as you add to the I beam
> > > So why not just go for the triangle in the first place?
> > > Is it because of the fore and aft loads?
> > > Or is it because of torsional distortion?
> > > Rgs
> > > Tony
> >
> > I think it is a designer's comfort zone kind of thing, at least
> in
> > the cases I described. a Pultruded carbon rod would change
> things,
> > but the designs I mentioned were timber. In that case the I
> beam
> > gives a nice little flat spot to spread the loads. With timber
> it
> > doesn't really pay to come to sharp carners where the loads
> rocket
> > way up there. These aren't squarish section i beams but ones
> where
> > the flange might be 1 inch, and the web 8-12", so any weight
> added
> > was trivial in the cases in question.
> >
> > Also the edge on plywood isn't all that stiff. Just helped
> build a
> > staircase about 16' run/rise, with a stringer of 16" depth
> (which is
> > huge), made of 1.5" maple/poplar plywood, three stringers, and
> it was
> > bouncy as hell. Normal dimensions would be a 1.5x12 stringer of
> > spruce, which is about half the depth of the ply stringer once
> cut
> > out, and would probably have been bouncy too.
> >
> > So when it comes to knowing the numbers, who knows. Wharram
> designed
> > the Tiki 21 to daysail and camp, Rory sailed it around the
> world.
> > All of a sudden a little flange just seems like good insurance,
> you
> > don't know where the boats will end up. Though I think that
> one was
> > GRP.
> >
> >
> >
> >
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