By the time you buy good quality ply, resin impregnate with a
protective glass skin and glue and glass joints, I couldn't get much
cheaper and certainly not lighter than polycore and glass. Polycore
with two 400g skins and resin comes to about A$110 dollars a 1200x
2400 sheet (including consumables) and abou 6kg (extrapolating from
Rob's friend at 2.3Kg/m2) with 600 and 400 glass. This is about the
weight of 6mm ply dry, which then needs stringers. I believe a
modification of the KSS system is possible for a Harry and this is
what I intend to aim at A certain amount of torturing should be
possible with a single skin and then fixed when the other skin is
added. I think it also posible to build in a certain amount of
compound curvature into the table before the bending. Derek Kelsall
is playing with that idea.
I actually prefer the resilience of the polycore to the strength of
the Kiri as tests I have read indicate it is better under collision-
see Nidacore website- and my own experience with polyprop supports
the results. I have a fondness for tortured ply with many
experience in small catsand dinghies, but I relly think its time has
passed for larger boats I would prefer to build in strip plank and
ply because I actually find it a meditation and greatly satisfying.
Seems such a shame to paint it and smooth out the strips to make it
look like a fibreglass structure. I intend to make my internal
furniture out of it for the looks.
regards,
robert
-- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@g...>
wrote:
>
>
> I believe there are a number of folks who would like to try
tortured
> ply, cylinder moulding, and KSS construction, but aren't sure
about how
> to replicate some of the compound curves found on the harryproas.
>
> If money were no object, and I were paying a yard to build the
boat,
> I'd go with strip-planked kiri. Although it would have some extra
> weight over corecell, I'd enjoy the peace of mind that comes from
having
> a solid structure even before the glass and resin are added.
>
> On the other hand, if I had to build the hulls myself, I'd be
sorely
> tempted by the speed of the other construction techniques.
Provided I
> was aware of a way to get those nice compound curves found on the
> topsides of harryrpoa hulls, of course.
>
> Any light you can shed on this issue would definitely be
appreciated.
>
> Congratulations on your proas, by the way. Is there a place
where we
> can learn more about them?
>
> - Mike
>
>
>
> jerry freedomev wrote:
>
> > Hi Robert and All,
> > I'd think a HarryProa wuld be easily built
in
> > tortured ply technic for much less money, labor, weight. Any
reason
> > why it wasn't used?
> > In it I've built a 28' proa with the room of
a
> > much larger Harry for under $2,000 in materials. And a much
larger 36"
> > Proa in about $3,000.
> > Thanks,
> > Jerry Dycus
> >
> >
> > */Robert <cateran1949@y...>/* wrote:
> >
> > From my own minimal experience, it is more important to get
> > reasonably accurate dimensions rather than finish as you are
going to
> > sand a lot of it away. If you are cutting the planks
yourself you can
> > get three different widths according to curvature and make
the
> > chamfered edge at the same time. If you really want to be
fancy, you
> > can glue all the strips to full length and taper and chamfer
them
> > before you start and almost completely avoid cheaters.
> > Techniques for using polyprop honeycomb are on the nidacore
site. It
> > is worth while looking at the impact testing of polyprop
honeycomb
> > sandwic compared with balsa core. A great lump of RSJ was
hoisted up
> > to the heoght of the shed roof and dropped onto the
sandwiches. The
> > polycore caused the RSJ to bouce up into the air without
damage while
> > the balsa fore fractured. I believe, though I haven't tried
it with
> > polycore that a hot iron can put creases into the face of
one side
> > to control bending and also to provide resin channels for
resin
> > infusion. I think it well worth using vacuum bagging to
reduce weight
> > and impove adhesion for high stress areas but at a price of
extra
> > consumables and effort but I am in two minds about infusion.
> > The difference in price is not worth hassling over. I'd be
tempted to
> > use poulonia in the high stress areas to save on glass and
polycore
> > in the flat, low stress areas to save on time and weight
> >
> > home.houston.rr.com/pieceofwork/index.htm is a good website
to check
> > out
> >
> > congratulations about having suport from your boss for the
project.
> > Good luck wit the finances.
> > regards,
> > Robert
> > --- In harryproa@yahoogroups.com.au, David Howie <dana-
tenacity@u...>
> > wrote:
> > >
> > >
> > > Part of the problem is to know whether you are comparing
apples with
> > > orangutans. That price for paulonia is raw planks, need to
be
> > dressed and cut.
> > > Don't know whether the planks are to be cambered on the
edges. Poly
> > sounds
> > > fascinating, lots of unanswered questions, how does
anything bond
> > to it? can
> > > an amateur work it successfully.
> > > Speaking of amateur I started off thinking I knew
something about
> > this boat
> > > stuff, but the deeper I dig the less I know.
> > > Pity there isn't somebody else nearby who was thinking of
building
> > a Harry.
> > > Trying to talk my wife into a trip to Aus when Bain's boat
hits the
> > water
> > > (presumptive of me isn't it?), she doesn't think much of
Aus, but
> > she has
> > > given the project the green light if the funding happens.
> > >
> > >
> > > ------ Original Message ------
> > > Received: Wed, 01 Mar 2006 06:26:30 PM MST
> > > From: "Robert" <cateran1949@y...>
> > > To: harryproa@yahoogroups.com.au
> > > Subject: [harryproa] Re: Materials list
> > >
> > > I couldn't get near that price for Poulonia. Suspect rob
can get
> > much
> > > better prices on glass and carbon. Probably worth the
freight. May
> > have
> > > to wait on carbon till the shortage is overcome and prices
> > approximate
> > > manufacturing costs rather than scarcity. Can you give
areas of
> > > materials to allow comparisons?
> > > My calculations for polycore are with no ply, larger
cockpit/saloon
> > and
> > > a cockpit cover like Bain's.
> > > Overall calculations are not that different. I get in the
order of
> > $30k
> > > sailaway with schooner rig, including consumables. only
$10k for
> > basic
> > > boat materials.
> > > Regards,
> > > Robert
> > >
> > > --- In harryproa@yahoogroups.com.au, "oceanplodder2003"
<dana-
> > > tenacity@u...> wrote:
> > > >
> > > > OK it's in files now.
> > > > >
> > > >
> > >
> >
> >
> >
> >
> >
> >
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