Glass work is not so hard
John, Sounds like you have a nice little project. I would suggest not taking a short cut in the process. If you do, it will only cause you to 'fix' it later, which usually is more costly. I have done a lot of glass work. Here is how I would suggest you go about it to minimize the work and maximize the results. First, fill the old hole, then install the new autopilot to the original instructions. Filling the hole is not hard. The steps are: 1) use a round course file to bevel the old hole from the outside. 2)Glue a piece of corrugated cardboard behind the hole. 3)Using latex gloves, cut a piece of fiberglass about an inch larger than the cardboard. 4) Use a small paint brush to apply resin on the cardboard and surrounding area behind the hole. 5) Spread the fiberglass matt on the resin. 6) Paint a heavy coat of resin over the fiberglass. This completes the backside work. 7) Cut 4 or 5 round circles of fiberglass the same size as the hole. 8) Cut one circle of glass slightly larger, the size of the bevel in the gelcoat. 9) Apply resin to the inside of the hole (on the cardboard). 10) Place a small fiberglass cutout on the resin and paint with a layer of resin. 11) Repeat steps 9 & 10 for additional layers, placing the larger cutout on last. The resin for the last layer should cover the beveled area. 12) Ensure the resin and fiberglass is lower than the surrounding gelcoat. 13) After the resin sets (overnight) mix gelcoat with white coloring and fill in the hole (popcicle sticks work best). Cover the gelcoat with a piece of transparency film (this is the material used to create presentations that are shown on overhead projectors. You can usually get an old one from your office). Be sure all bubbles are removed and tape in place. The surface will dry to the shape of the transparency film. This will reduce the amount of sanding that needs to be done and hold the gelcoat on the vertical surface. 14) Use a small block of wood with 220 grit sand paper to finish. The fiberglassing should take about an hour. The gelcoat should take about 20 minutes and if you were very careful in placing the transparency film, the sanding should take about 5 to 10 minutes. Hope this helps. Bruce.
Thanks, John