[C320-list] mounting in fiberglass?

[Joel Krauska]

Sorry if this post is naive, but there's a first time for everything!

General question:
How thick is the fiberglass on the boat on average?  1"? 2"?

Actual issue:
I'm replacing one of the round cabin lights in my forward berth.

The old mounting holes don't line up with where the new mounting holes need
to go.

Fiberglass is tough stuff!

Any hints on doing a surface screw mount?

Predrill a hole?
What size bit?
How deep?
Hammerdrill?
Special bit type?

Should I use expoxy or something to help set the screw in the glass?

Is there something I should /treat/ the fiberglass with to soften it before
I screw stuff in to it?

Mostly I'm worried about popping a hole up on to my foredeck on accident,
but I'd love to hear how other people do this.

Thanks,

Joel Krauska

Grace #802