One technique we used in the ole south - that actually works, is taking your cables and doing a loose knot at a point closest to the power source. The knot creates a magnetic field that causes the cable to blow apart there - but doesn't allow the rest of the current to travel any further...That is a very low tech solution for protecting gear. However this is good reading:
Link
For most in hull grounding to be effective on a fiberglass boat, one of the techniques was the copper plate running for to aft with additional copper looping from port to starboard to create a
Faraday Cage...
There is nothing to prevent a lightening strike - just various techniques to minimize the effect...if your boat is properly grounded, and such...(and seems there are tons of products that promote something that aides etc for it)... none of them are lightening proof...and usually due to the mast and the tallest structure and usually the backstays and forestays are not grounded out to the water - there is only one direct path and that is in the boat and out whatever path your boat has....