Oops. Got the Harryproa link wrong in the previous post.
http://www.harryproa.com
---
Thanks for the detailed description of what you've been doing.
If you want to find a wider-interest discussion group in which to
post further details, I'd recommend the Proa File at:
http://groups.yahoo.com/group/proa_file
. Many people from this group
also participate over there.
If you'd like to learn more about the harryproa design, there are
lots of good resources, renderings, and articles at:
http://www.harryproa.com
.
- Mike
freedomev wrote:
Hi Rob and All,
--- In harryproa@yahoogroups.com.au,
"Rob Denney" <proa@i...>
wrote:
>
> G'day
> First, a belated welcome to the group. Great to have someone of
your experience on board.
Thanks, I try to help where I can.
>
> My first proa was tortured ply. Worked well. The first Harry was
actually bending ply (2 thick outer softwood veneers, a middle very
thin one at 90, could bend to 150mm/6" radius. Also worked well.
However, for the hull shapes we wanted, strip was much easier. See
also Robert's reasons for not using it.
I've never seen the Harry design lines so hard to say but
I've been able to make most any faired shape with tortured ply. It's
mostly a matter of changing the variables like ply thickness, plys,
bendability, cut of the exaggerated profile, bulkhead shape and
placement, thickness of the gunnel. As it's so much cheaper, faster
you can build one just to experiment. A 40'hull takes me just 10 hrs
to build!! I'm over 100 tortured ply boats by now over 25 yrs.
For ply I use an excellent though cheap Southern Yellow Pine
ply as it lasts almost forever and bends somewhat, allowing a much
thicker ply hull than even WEST System people, 6mm, say you can but
my next one, a 26' tacking proa will use 12mm about. If you want to
use thinner ply, it should be stiffer type, more plys, and the
thicker you go, the more bendable, fewer plys it needs to be to get
a round bilged excellently faired hull. I almost never used
stringers in my boats, instead making the interior part of the
structure giving it more strength without weight. With your
selection of plywoods and such better prices than we have here, I'd
love to be there!!
As for srength, the earlier cat I mentioned, the 32' Java
cat rammed a 75mm iron rebar sticking out of the bottom he hit at
about 8mph and gashed a large hole. He thought he was sunk 8^0.
But Steve Brown and I were thinking about the ability of
hitting something at sea because of our high speed, we needed to do
something so we built in a 45deg crash bulkhead behind the bow from
1m high to aft at the bottom. Thus the owner just backed off the
rebar rod and didn't sink!! He was amazed and motored back to the
harbor and it's boat lift without a problem.
With well thought out joints, a tortured ply boat can easily
stand much abuse. I designed my multihulls to sail over reefs, be
beached in storms at high speed to without much damage as it may be
survival tactic because during bad storms, many inlets can't be
used, especailly here in Fla, Carribean.
For those wanting better crash protection, using a layer of
Kevlar or similar aramid cloth on the outside of either ply, plank,
or fiberglass hulls. I'm building a composite monocoupe body/chassis
EV for production and I'm putting a layer of Kevlar on the inside
for crash protection to hold everything together in a very bad
crash. My first one was done in epoxy/ply though 8^)
http://www.austinev.org/evalbum/168.html
The white one is the
mock up for my composite EV which the tooling is now done and
building the first one. Browse around if you want to see some rather
cool EV's!! Several from Aus.
http://www.evproduction.org/wiki/index.php?title=Progress_Pics
Here
are some pics of the new version.
I now don't use glass on my ply except under the waterline up
100mm above it, mostly for worm protection though I make a 25mm dia
glass keel from bundling up unidirectional glass like chopper gun
feed for cheap or uni glass sheets rolled up into a bar that's put
on the botton centerline to protect the bottom in grounding. this
can be used anywhere one neds extra strength like crossbeams, ect. I
also use it in my EV as a rollcage/frame between the innner/outer
skin.
>
> I am currently discussing with a couple of prospective builders
using Kurt Hughe's cylinder moulding technique. With some
variations, this also has potential.
That's a good one as is Constant Camber. If you really want to
sell composite ones, making a mold from one for others to use would
greatly speed up Harry construction. Finishing a raw fiberglass
construction is hell.
I like wood/epoxy as you can finish it clear and the
imperfections of being perfectly flat just don't show, saving much
time, materials.
I would be very interested in hearing more about your Proa's, design
and construction.... performance... lol... tell all... the more
details the better. :)
eagerly awaiting
Scott
This doesn't seem to be the list for that though I'd like
to find another Proa/or multihull list that has a wider range of
interest if anyone knows of a good one, please let me know?
Almost everything in the technic is in WEST System Manual
which is where I learned it from 25 yrs ago so thay's a god place to
find out about it. Anyone doing wood/epoxy should read it front to
back and you wil build a much better boat. I don't use their epoxy
as too pricy and stiff. I like epoxies for wood to have the same
bending, strength traits so you don't get hard spots that cause
fatigue breaks.
HTH's,
Jerry Dycus
>
> regards,
>
> rob
> ----- Original Message -----
> From: jerry freedomev
> To: harryproa@yahoogroups.com.au
> Sent: Friday, March 03, 2006 8:57 AM
> Subject: Re: [harryproa] Materials list, Price!!!!
>
>
> 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
>
>
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