Subject: Re: [harryproa] Re: Materials list, Price!!!!
From: "Rob Denney" <proa@iinet.net.au>
Date: 3/4/2006, 8:06 AM
To:
Reply-to:
harryproa@yahoogroups.com.au

The plan is to glass one side of the Polycore first to make it stiff enough to hold it's shape.  The big saving will be the lack of fairing as it will come off the table smooth and fair.  The downsides are yet to be discovered.....
 
regards,
 
rob
----- Original Message -----
From: Mike Crawford
To: harryproa@yahoogroups.com.au
Sent: Saturday, March 04, 2006 7:57 AM
Subject: [harryproa] Re: Materials list, Price!!!!

<<You have longitudinal strength in triaxial where needed... Don't really see how a resin filled seam weakens the structure as it is part of the web of the I beam structure.>>

  I'm familiar with sandwich construction, and I don't question that you can make a world-class boat out of polycore. 

  I'm just fond of a boat that has some reasonable structural integrity even before the glass goes on.  A resin seamed tortured polycore hull isn't going to hold much tension (or shape) prior to glassing.

  Thanks for the nidacore reference, by the way.  I need to replace the bunk shelves in my current boat, and this looks like a much better solution than the plywood I inherited.

       - Mike


Robert wrote:
-You have longitudinal strength in triaxial where needed and extra
uni in concentrated areas. A bit of movement in the structure
shouldn't matter provided the material isn't brittle and the stress
and strain parameters coordinate and the bonding is good. Don't
really see haow a resin filled seam weakens the structure as it is
part of the web of the I beam structure.

regards
robert



g-- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@g...>
wrote:
>
> << 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>>
>
>   I think that kiri or cedar would probably test differently than
balsa,
> but I'm still willing to buy the argument.  For the sake of
discussion,
> let's say that polycore is stronger in collision.  But what about
as a
> complete structure taking a pounding in a storm?  That's a
different
> kind of strength.  I'd have more faith in a strip-planked boat with
good
> longitudinal strength throughout the entire hull, than in a cored
boat
> that's going to have resin-filled seams that won't offer as much
structure.
>
>   That's really the crux of the matter for me.  What's more
important:
> collision or pounding?  I'm personally more concerned about the
latter,
> but there's clearly no right answer.
>
>   Of course, if tortured polycore could save me a few hundred kg,
and/or
> a thousand hours, I'd put the intellectual argument aside and jump
on board.
>
>        - Mike


>


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