One of the curses of aluminum boats is corrosion where the railing posts are screwed to the deck. In the first photo the railing has been removed to reveal the usual mess below it. (The deck in this particular location had the usual "minor" paint blisters showing, and black crud had built up below the rubber gasket.) In the next photo the mess has been sanded down to bare metal. Note that corrosion is halfway through the deck in one spot! This was the worse case, but every post had some level of corrosion growing under it.
In the next photo, the aluminum step plate has been removed. Note that, though is a bit of corrosion near one of the screws, and some black crud hiding below it, there was none of the deep, ugly corrosion found under the railing posts. My conclusion: Those rubber gaskets are bad news!)
In the next photo, I'm installing aluminum rivets in 17/64 inch drilled holes. The homemade rivet setter in the left photo works great if there's room to swing the handle. When there isn't, a ratchet and grade 8 bolt and nuts have to do. Get several for they wear out.
In the last photo the aluminum rivets have been 'set' and 1/8 “ thick plastic washers are glued on top of them with silicone (since the washers are tough to locate under the posts unless they are glued in place.) A rubber gasket is NOT used, to prevent moisture trapped below the gasket setting up a corrosion cell.
Update: After 4 years, the railing bolts are all still nice and tight, and minimal corrosion has reappeared under the posts.
