I have a couple of stripped out holes in my boat where a screw is into a layer of fiberglass and then wood. One is for the outside rail and the other is for a snap for the cockpit cover. Is there a Bondo type putty I can fill the holes with and then redrill? Is there some sort of insert I can use? Thanks for any help you can give.

Since neither hole you are dealing with is for anything high stress, I think you should be able to get by with a quick and dirty trick I've used many times over the years. It is nothing more than toothpicks in the holes and then put the screws back in. In some cases I've used a dab of glue on them but sometimes that isn't even necessary. Good luck.
John

Dowel rod is your best bet. Drill the hole slightly oversize then epoxy it in.

theres a few ways you can go about this:
you can go to West Marine or BoatUS and get some MarineTex....its a bondo type putty you mix up and fill the holes up with and redrill as you were saying...

You can also mix up some resin with a filler like micro-balloons etc into a peanut butter consistancy paste and fill the holes up with that.....or

the cheapest and fastest way, you can get some 5min epoxy from homedepot...some toothpicks....mix up a batch of epoxy and glob some on a bunch of toothpicks (how ever many will fit into the hole) and leave them there till the epoxy sets...then cut flush with side cutters and you are back in business

guess i was typing too long and got beat to the punch!

MarineTex great stuff better than new.

You can also take a piece of zip tie and stick it partially in the hole. Start the screw and then cut the zip tie off as needed so the screw goes clear in but the zip tie is not sticking out from under it.

I've done the piece of zip tie and used some strands of wire as well and then put a little 3m 5200 on the threads so it won't vibrate loose.

If all else fails, just put a bigger screw in it

Not for every hole, but it's hard to beat a small machine screw with a flat washer and nut on the back side. Of course it needs to be accessible.