cutting fibergass hole

i have always used my angle grinder and cut off wheels. or even my dremel for tight stuff. I also like to drill holes at the corners and connect the dots. a round hole is less likely to start a crack then a sharp square corner. as said. use masking tape. 2 layers min. if your going to use any tool that has a base that rides on the hood while cutting (like jig saw) use 3-4 layers of tape so the tool base dont gouge or scratch the gel coat. a foam sanding block will dress the edges nicely. id use 120 grit.