Cutout repair steps

After removing any remaining caulk from around the openings,  I ground down the glass so there was a long bevel of about width of the radius of the existing opening.  A large piece of 1708 was cut out with ample overhang to give a good bond to the back surface.   These pieces were laid out on a piece of Peel Ply  and pressed perfectly flat and smooth.  They were then soaked with epoxy and left to cure.  After curing a bead of thickened epoxy was spread around the outside edge where it would contact the back of the opening.   The pieces were inserted behind the existing glass work. 

There are any number of ways to keep the pieces pressed up against the backside while the epoxy cures.  It all depends on what you have to work with.   In this case,  I opted for the bungy chord method.   A small hole was drilled in the center of each piece and a loop of line fed trough with a small nail to keep it from pulling through.   Then bungy chords were attached to the loops and connected to an anchoring point directly opposite.  This creates a enough tension to keep the pieces from moving while the epoxy sets.    Remember to wipe off any squeeze out that occurs inside the opening.   I didn't and it only created yet more sanding to do.

Once the backer pieces have cured your can go ahead a layup your glass to fill in the hole and fair it to the hull surface.   Notice how much area is ground away around the openings.   This gives a nice large surface for the glass layup to adhere to.