I don't have a metal boat, whether it a lumi or steel, but I have seen some damage done, whether it's sitting at the dock or purposely caused by de-rust parts.
A few questions :
Is this a salt water boat ?
Will the boat be in the water year round at a marina ?
Most of the time the damage is caused and accelerated due to electric power leaching into the water. usually at marinas
If you hang a piece of zinc in the water, that will draw all of the damage before anything else.
I'm not a chemist, but what I know is electrolysis requires two metals and a salt bridge. The salt bridge is usually slow,but over long time will do damage. But if you introduce a power source to the salt bridge ?
You can watch the metal disappear.... so to speak ( see the de-rusting of the gas tank thread in the main forum)
Aluminum boats (& aluminum fuel cells [esp below decks]) also suffer when water is trapped between 2 surfaces too long w/ no air movement to encourage the water to dry. Water sitting in the drip rails around hatches, water between foam & a fuel tank that wasn't painted 1st, in a folded seam in the hull, between wet wood & aluminum, etc. It does NOT have to be dissimilar metals, although that certainly makes it worse.
In many cases it looks like a flimsy, swiss cheese hole filled mess.