Subject: Re: [harryproa] Building methods / materials
From: "Rob Denney" <>
Date: 4/9/2008, 11:29 AM


Col is a very smart bloke, has been designing boats for yonks and has
always been full of ideas, most of them good. Experimentation is a
good thing and so is caution , so talk to Col and at least a couple
of people who have built with it. Maybe build his little canoe as a
test. Then do the numbers and decide which suits you best.

I worry about corrosion of alloy and screw attachment of ply, which
often rots around fastenings unless they are individually over
drilled, filled with glue and redrilled. I also think
glass/ply/alloy will be heavier, maybe more expensive and require
more finishing. Could be wrong on all counts.

If you talk to Col, say hi from me, tell him your boat will almost
certainly be 20mm foam or Polycore with one and a half layers of 600
double bias each side and some serious strength required around the
mast and the beams, but no other bulkheads. Surface area of
Visionarry lee hull is 57 sq m. I will be very interested to see
what he suggests, and how it competes with the panel build method.
Also ask him about the large flat)ish) cabin roof and floor areas



On Wed, Apr 9, 2008 at 3:40 PM, Tim Barker <> wrote:
> Hi Rob/ all
> Visited Col Clifford today , as much to see his radial engine as have a
> yack about build methods, very interesting guy and very cluey.
> What are your thoughts about the alloy internal frame system , as a
> person who has done quite a bit of metal fabrication it makes sense to
> me and offers some build speed advantages as far as i can see . Coupled
> with the idea of glassed ply skins it should be very cost effective
> tough and simple to build.
> For those on the site who arent familiar the method involves standard
> ally extrusions and cast ally fittings which allow the frame to be
> fabricated from ally without welding, it is then skinned in ply or
> composite however the skin basically only has to act as a waterproof
> membrane not as a structural member and also to hold the structure in
> tension, light strong simple .
> What are the various opinions out there.I myself am very suspiscious of
> ply or timber however i know that this is a fairly basless predjudice
> given modern methods and materials hence the ongoing investigation of
> different methods and materials.
> Coupled with the relative costs of some of the composite cores on the
> market and the slowly dawning realization that using these composites
> may result in a craft not much lighter (if at all) but substantially
> more expensive than a craft using ply skins has certainly eroded my
> predjudices.
> Cheers Tim

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