Subject: [harryproa] Re: Dimensions
From: "Robert" <>
Date: 1/11/2006, 8:49 PM

-1200x2400x10mm sheets $83 for polycore< $30/m2. This is the higher
density scrim that virtually eliminates resin ingress to the core 80-
90kg/m3 The compressive strength is 2.6MPa/m2 and sheer 0.5MPa. Check
out Polycore_Australia

Kiri $1.98linear metre 42mm wide up to 10mm thickness dressed =nearly
possibly get down to $35 undressed I think in the order of 270kg/m3
(need to check this figure)

All of these prices can come down with larger orders but they provide
a reasonable comparison with each other.

Need extra glass for the high stress areas for the polyprop to
compensate for the longitudinal stiffness of Kiri. possibly need
extra resin to saturate the scrim but this is ameliorated by reducing
bog.  There is a slight print through for polycore with chopstrand
but I wouldn't expect as much with the knitted fabrics..
Polyprop starts to soften at about 80C so I wouldn't use it for
boiling water but it should be quite good enough for any conditions
we are able to stand. This temperature range allows moderate heating
to allow shaping though I haven't found techniques for one off
building in my searches. I have used a hot household iron to shape
polyprop foam on a boogy board and I intend to try this technique on
the honeycomb to make grooves to encourage bending and for thinning
panels near the edge for joining without excessive fairing.
The glassed panels are transluscent and I was admiring the cockpit
floor and bunks of Bain's harry before painting as they allowed a
fair amount of light into the hulls. I am seriouslu considering using
suitable resin to leave sections above the waterline unpainted where
they don't get direct sun but it would mean much neater joints than I
am probably capable of.

Techniques for using polyprop honeycomb are on the rival company's
(nidaplast) website.
You can probably save in the order of 1-1.5kg/m2 or 30% of the
weight of the skin depending on thickness of cores, glass weight
glass resin ratio etc. Possibly more if you include fairing bog.
I believe it is suitable for using the KSS process and I think the
Harry hulls are suitable for the process, or even simpler process
with their lack of rocker and foam bows.
I have been checking out resin infusion. A good starting point is the
kssboat yahoo group. The general consensus from the group is that if
it is worth vacuum bagging it then you may as well resin infuse-
especially if you are short-handed.
Overall slighly cheaper for polycore, probably quicker, better
resilience, no chance of rot though as kiri is a very low rot timber
this is not a big factor, not as good for compound curvature but this
isn't much of a problem with a Harry. My main objection is that I
like working with wood but the weight savings can't be passed up.
I'll just have to have wooden trim. 

-- In, David Howie <dana-tenacity@u...>
> Tell your wife I've done over 150,000 miles. What really attracted
me was the
> idea of simplicity, a true minimalist boat. When you've lived on a
boat with
> two heads, hot and cold pressured water, generator, etc.etc.  etc.
you realize
> that all you do is repair/maintain equipment instead of enjoying
yourself as
> planned. I want to get back to the style of my first boat: compass
sextant and
> leadline. Interesting in one of his articles Rob said he started
off by
> looking at a simpler rig and ended up simplifying the whole boat.
> Rob, whats the current state of affairs with this poly honey comb
business? Is
> it better faster cheaper? Are you ready to run with it? Is it
available in
> NZ?

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