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