Well I didn't want this to turn into a lengthy exchange but I am befuddled by that last post from bflat. This is an interesting subject and it won't hurt to discuss it a bit more--might help in fact.
That quote from a meteorology professor is mighty strange. (I might mention that I happen to know an ex-meteorology professor who said that humans cannot possibly be the cause of global pollution and climate change--so go figure.) It is a statistical fact that boats are hit by lightning from time to time but it is very rare and not ever having witnessed it at a marina is merely anecdotal. It is a documented fact that boats have been struck by lightning--sometimes with extensive damage, sometimes with no damage at all. For example, that mention I made of boats being more likely to be damaged in fresh water was from a study by the Florida Sea Grant. Must have happened or they would have had nothing to study.
What I know about lightning is very limited, but I do know that it can be seemingly capricious and unpredictable. Scientist who study it are often perplexed, for example, who can explain ball lightning? What is known is that lightning is caused by a buildup of an immense static charge by friction in the clouds, and the charge can become so high that it arcs to the ground from miles up in the air. My own house was hit by lightning and suffered some damage (before I moved here) and lightning has been observed hitting lightning rods and antennas, and masts of sailboats, so I don't see what the "immense size of a lightning bolt" has to do with anything.
For what it's worth, I have a theory about why you don't see it that often around moorings with large numbers of boats. There are a lot of very expensive boats there and I am sure most or all of them have properly grounded masts. It is possible (and again this is just a guess) that the large number of grounded masts is able to dissipate the charge in smaller amounts that are not visible or noisy. (This sort of thing has been known to happen.) There is a thing called the "Cone of Protection" (not to be confused with the "Cone of Silence"
) that is provided by grounded masts, lightning rods and so on. The cone's apex is at the top of the mast or rod or antenna, and the radius of the bottom of the cone is equal to height of the mast ( or whatever). The taller-masted boats could be providing many of these cones that protect the other boats.
Or there could be a tallish building on shore whose cone extends out to the moorings. Or the sea is so vast that it is dissipating all the charge. Or maybe your professor is right. Who the hell knows? At any rate it is a very interesting subject but it's not going to keep me off the water unless thunderstorms are imminent (then I would have plenty of other reasons not to venture out). If I can ever get in some multi-day cruises and a storm comes up, I'll just have to take my chances.
By the way, I can remember one time when I was in a small, open aluminum boat on a lake in Alabama when a thunderstorm came over. There was lightning hitting the water within 200 or 300 yards of us. It was very scary, especially way back then when I didn't even know what little I know about it now. For example, I thought the electricity could travel through the water and come up and electrocute me through the metal hull. Anyway, I survived that unscathed, so relatively speaking I will feel much safer inside the cuddy of a PocketShip (with the mast down).