Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Thu, 28 Nov 2002 21:27:54 -0500
Message-ID: <redirect-1890857@logan.com>
From: Newlan2dl@aol.com
Subject: Re: [LML] Re: Body Work
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Hi Bob

On those spider cracks, were they on top of the cored areas or on the solid 
laminates?  And was that near a hot spot on the engine?  If it happened on 
top of the cored area, I'd router out the core, laminate in a couple layers 
of tape, recore with high temp. epoxy/ microballoons/fumed silica (Cabosil) 
then retape over it.  

If it's on the solid laminate, is there something poking it from underneath 
that's stressing it?  Check that first.  If not, you need to take off the old 
repair fabric and try some more layers of tape but I would use carbon fabric 
in the plus/minus 45 degree and zero- ninety degree orientations.  And you 
will have to grind out most or all of the old bad structure since that has 
apparently fractured anyway.  If it's thin skinned, you may have to do this 
in two steps.  Laminate in the repair tapes and once hard (but preferably not 
cured), grind out the old material all the way down to the newly laminated 
repair tapes.  Essentially, the repair tapes are used as a form and you end 
up with all new material in the area.

Anyway, it is important to give it several different fiber orientations.  
This will give it quasi-isotropic strength.  Use a high performance toughened 
epoxy like Applied Poleramic's DR-5 or hi temp DR-7, and lastly, vacuum bag 
and peel ply it.  This will give more fiber for the thickness and with the 
toughened epoxy, be a LOT more crack resistant.  For carbon fabric, here are 
a number of outlets but you can get 5.7 oz plain weave from Svendsens Marine 
at (510) 522-7860 and they can ship.

Applied Poleramic is in Benicia, Ca. (925) area code but I don't have their 
number here.  They do sell gallon quantities and they are pretty reasonable 
in price.

Dan Newland