Re: 1988 Sea Nymph GLS - 17'
PMC, I'm considering a bare hull as well, so I've been reading a ton on this subject on various forums. This is a good quote from a poster on "capmel.com," a Florida fishing 'zine, regarding bare aluminum hulls, both welded and riveted, in salt:
Aluminum boats are much more popular on the West Coast (of the US) than here. I still keep one out there that I've had since '98. The bottom is unpainted and it has held up just fine.
There is no reason to paint an aluminum hull except for cosmetic purposes unless the boat is kept in the water. In that case you need to use special bottom paint that contain no metal at all such as Interlux Trilux. They leach hydrogen peroxide instead of metal to inhibit growth. Rustoleum or galvanizing paint will cause galvanic corrosion when submerged in saltwater.
If you leave the hull bare, it will rapidly take on a dark "patina" that will inhibit further oxidation. As long as you control galvanic corrosion with zincs on the transom, the hull will last longer than the rest of the boat.
A product called Sharkhide is very popular out west among people who like to keep their boats shiny and new looking. You can put it on yourself, but it has to be re-applied every few years.
Riveted aluminum hulls don't hold up as well in salt water as do all welded designs. That's in part because the folded parts of the hull and the areas under the rivets are subjected to crevasse corrosion. Oxygen can't get in to produce a protective oxidized surface layer. So the rivets loosen faster if the boat is used in salt water.
I've read several similar discussions regarding riveted aluminum boats in salt water...and they all say that if it's trailered, you have nothing to worry about. Take this for what it's worth, as it's all just internet knowledge to me. Cheers.
