Ok, I've got this far on the repair. What's my next step? I have epoxy and microfibers on standby, what else will I need? Can I just stick the bottom pieces back down, or will I need to tape the seams and blend in as well?
Gonna be waay better with new divinycell (Herex etc)
Short version that will work:
Fill foam with epoxy/q-cells (about honey consistency) an scrape off well with squeege so only filling the holes. Allow to cure.
Sand flat
replace divinycell - use epoxy q-cell mix again but a bit runnier this time, and make sure both surfaces are coated, bung in the d'cell then a sheet of plastic over the d'cell, then a piece of cardboard about same size (or tiny bit smaller) and sandbag it. Then tape around the board real tight with plastic masking tape (poor mans vacuum bagging 
Once cured, feather out edges of glass about an inch and give it 2 x 4oz glass.
Almost 3hrs and haven't come back yet
Madly trying to undo mess with acetone..... or going so well you are still looking at it with beer in hand?
So little faith. Needed to wait for the temp to come down a bit. It's hot here.
First I sparingly wet everything out with resin.
The mixed microspheres into the remainder to make the glue/filler. I was aware I didn't want this on too thick, which would prevent the skin pieces from settling down, so I scraped at lot of this out.
In retrospect I should have filled and faired the chunks out of the foam before going for the final glue up. Live and learn.
Builder's film over the top followed by strips of cardboard (trying to preserve the concaves...)
And then bags of gravel for weight. Luckily I live right next to a Shinto temple, so I have access to lots of gravel (those guys really shouldn't take Sunday off.) 
Select to expand quoteikw777 said..
In retrospect I should have filled and faired the chunks out of the foam before going for the final glue up. Live and learn.
I do seem to remember saying that 
I reckon it will be fine.
IF the monks don't come over and smash it up
If I'm not happy I'll grind it out and start again. It's just a glass over foam board.
Ok rocks are off and I've done a little sanding. I'm quite happy with the way the contours of the bottom have turned out - mostly preserved I think. I'll let this cure for a few more days and then I'll grind out a depression all round for glass tape... Then big blue can return to action, shredding up the Bay.
