During my career as an Italian marine surveyor, it has happened to me to survey boats struck by lightning.
I have to say that it is not very easy: one runs the risk of underestimating the extent of the damage and the components involved, and of not identifying everything that has been compromised.
The lightning-affected boats that I surveyed were always sailboats. In all the cases I analyzed, the boats were either in port, in the winged yard, or in the roadstead-that is, none of the boats were under sail.
It is important to consider that often, if the boat at the time of the accident was in the boatyard or in port and the owner was not on board, you only realize after some time what has happened. As long as someone does not go and turn on the electrical system, it will be very difficult to see anomalies from the outside.
All of the boats I have surveyed that were hit by electrical storms had only the burned masthead vhf antenna on view and only one had remnants of it on deck. Unfortunately, lightning-related damage will be of greater magnitude on boats with more developed electrical and electronic systems.
When I appraise a boat that has suffered this event I always have the support of an electrician I trust and certainly never lack an interface with an expert in on-board electronics also because I am often asked not only for an assessment on the extent of the damage but also and especially an economic assessment of the repairs.
I can say from experience that from such an event it is necessary to check every single electrical or electronic control unit on the boat, even the most distant one such as the bow thruster or the watermaker.
I always advise my clients to insure the boat with policies and bodies and in the commercial assessment have the marine surveyor detail every electrical and electronic accessory as best he can precisely so as not to create gray areas in case such a claim is reported.