Mirror 68440 - Doc is a wooden boat built in 1987 and in June 2014 was damaged during a training session at Restronguet SC. Collision was with the bow rubbing strake on 15563 - Blyskawica.
First step was to cut away the damaged glass fibre tape & resin and most of the damaged ply with a sharp chisel. Then remove varnish around the hole using coarse sandpaper (80 grit used dry). Then I marked out the area where the patch would go with a very short ruler and marking knife across the grain and ideally a scratch awl (if you have one, or something similar) along the grain (don't cut too deep). In this case the damage was just above deck level, so I used the surface of the deck to define the bottom edges of the patches. Because the damage runs over a join, the patch in the topsides has to be longer than the visible hole on the inside, and run all the way to the outside face of the bow transom, so I didn't draw around a cardboard template as I would with a floating patch in one panel.
Made up patches and glued them in. Very awkward place to get clamps into, could only get one of my deep throated clamps on each patch because of the bow shapes. Once patches are glued in, clean up with sandpaper etc. prior to adding glass fibre tape and resin. I use 40mm wide open weave tape (it's easier to wet out and get to go nearly transparent) and after the resin is dry, rub down and apply a second coat of resin. This is just cosmetic, but it makes a smoother surface to varnish.
With tape and resin dry, rub down with fairly fine wet & dry (I used 240 grit) used dry so the varnish will bond. Using International two-pack, first coat was thinned with International Thinners no. 9. After that I was able to put on two coats per day to build up the coating thickness (weather was warm which helps) and rubbed down every two or three coats. I applied filler (epoxy resin & filler addititve) to the outside and rubbed down prior to adding more paint.
After the final coat of varnish and paint, the repair is complete.