[US27inKS]

I agree with Chuck. The balsa core causes the deck to have structure much like an I-beam. Without the interior fiberglass, you've got nothing.

What has been done with success, but more work initially, is to save the interior fiberglass as a panel. Carefully cut around the area you wish to cut out, and very carefully remove the fiberglass by cutting the core out. Then you can grind off any remaining core material from your panel. Then you can replace the core. To reinstall the panel, wet out the balsa core, the apply thickened epoxy to the panel. Prop the panel in place making sure it has good adhesion all the way across. Then fix the cut lines and you're done.

Or you can do what I did. Hold a 50 x 60 inch piece of dripping wet 18-2 biax over your head for about an hour.

 

[US27inKS]

You're forgetting a very important part of repair from the bottom GRAVITY! Use vacuum bagging!!! What ever the interior skin was made of lamination wise I should be put back with the same schedule.

I can assure you that without vacuum bagging this job will be harder, and come out with more gravity voids than doing it from above and repainting the decks. You make it sound so easy and I wish you luck!!

I tried vacuum bagging mine, with no luck. I couldn't get a good seal on the stupid thing. So I used a piece of light plywood (3/16 if I remember) and braced it in multiple places. Yes it sucked.

 

[US27inKS]

I'm still trying to figure out why you are wanting to do twice the work, just to save a can of paint. Are you afraid the deck will look so much better than the topsides that you'll have to paint the whole boat?