I'm renovating a 35yr old, 14' aluminum hull and used Gluvit to seal the interior....I have a thread going here that I update...
http://forums.iboats.com/showthread.php?t=299404
The interior paint was worn and there was some rust stain from a steel gas tank sitting in water. I may have overkilled a little but went all the way with the prep...
1) Scuffed the paint with 80 grit sandpaper
2) Applied a gel type paint stripper
3) Scraped the blistered paint
4) Wire wheeled the stubborn spots, seams and around rivets
5) Acid washed with phosphoric acid and a Scotch Brite pad
6) Thoroughly rinsed and dried
Gluvit is expensive ~$45 a quart and you do need to mix it thoroughly. I was mainly interested in the seams and rivets. To make sure it creapt into the seams as much as possible, I tilted the boat then applied, allowed to cure then did the other side. Using a roller and foam brush, I was able to get a good coat on the entire floor and walls of the hull.
Gluvit has no UV protection built in so it needs to be painted. Just be sure to scuff and wash the surface before painting.