Try sailnet.com
I've been looking for information on the same subject. At sailnet.com they have a bunch of articles on all kinds of subjects. Do a search using "grounding", "lightning", "electrical" or something along those lines...can't remember exactly what word I used. There's one article in particular that even talks about the proper dimension/material for a grounding plate (if needed) and also what size wires to use to bond metal items together. Good luck.Aubrey, GusBus II