Spend a few days reading on lightning strikes, here on the forums
, & online. Professional Boatbuilder
magazine is an excellent reference www.Proboat.com
as those who write the articles in it are incredibly sharp, & tend to be at the top of their specialties in the various areas of boat construction, design, & repair. Ditto on onboard systems. Or at least such was the case the last time I read an issue.
As to lightning, a strike can make things look horrid, but cause primarily cosmetic damage. Or there can be little evidence to the eye, but the damage is catestrophic. Which, the latter worries me. As, for example, a strike can destroy a good percentage of the resin in some areas of the boat without such damage being visible. And this would of course destroy the hull in those areas, structurally. But since glass doesn't conduct electricity, there can be just enough cooked resin & paint
in place so that the damage isn't visible, nor obvious. Even though things in that area are toast.
So with such damage, or the possibility of it, short of some really fancy, & in depth
Non-Destructive Inspection/Testing, I'm not sure how you'd rule
out a boat as not having such damage. However, figuring out specifically what sort of testing might work in such a case, & who's qualified to do it, could be quite a challenge. And once you did find the right folks, odds are such testing & inspection will be very expensive.
Look up NDT forums
(non-destructive testing) www.ndtforums.com/
, & similar, online. They'll likely have better insight into this. Though there's definitely some info on the subject here on CF. And if you want to "pay it forward", once you do some self education on the topic, come back here & tell us what you found/learned; please.
BTW, with lightning, it's not uncommon to see that it exited the boat in quite a number of areas. So that it may have done damage that is both visible, & non, in lots, & lots of areas.