my limited understanding is that with lightning you really don't want to be the "spark gap" that gets bridged when the massive pulse comes through

i can see where an alloy mast makes a perfect antenna for the charge cloud to gather around and if it gets struck that the flow down to a glass hull would try to limit the flow and get carbonized in the process, sinking a glass monohull.

a wooden mast probably wouldn't have the same problem. be interesting to know if that sunfish was an oldy with wooden mast and board or a more modern sailfish? type with glass hull and alloy mast

on a cat like my old nacra there would be fireworks when the pulse came down the mast and met the nylon ball pivot, but from there it would streak out along the main beam and then discharge through 2 hulls, might be more sparks at the beam straps depending on size of the strike...

on my 5.2 the charge would also flow back to the rear beam via the mid-tramp pole so you probably wouldn't want to be sitting on or touching the rear beam when it came through (or holding the rigging) but the more paths to carry the charge the less the damage i think

but for most beachcats with rotating masts i'd say there'd be a big bang from the mast base, and maybe some molten nylon flying about, but as long as you were on the tramp/hull you might get a shock but not the massive burns that kill lightning victims

airliners get struck by lightning all the time but because the charge can't conduct anywhere they rarely notice anything but the bad weather. on inspection you can find tiny fused pits around the skin rivets where a bit of corrosion put up a fight against the flow and got fused as a result

final bit from the lightning useless knowledge pool

if walking in an area with a high chance of a lightning strike try to keep your arms and legs close to your sides so any plasma pulse flows around the body and smokes your clothes off. you really don't want it flowing between your legs and going between your arms and chest as the resulting constriction is likely to increase the burns at the most vulnerable parts of the body:o)