Any of the non epoxy based paints, that are made for under water, will work pretty good, rule of thumb is use non-epoxy type paints below water line if bot is not going to be in water more then three months at a time, although most paint would go six months without a problem, if you are using a good grade.
Another general rule of thumb is if that boat goes 80 or faster, best to have an SS below the water line, this is just a general rule that has been used for years.
Two of the best, since Imron is no longer imron, is the glasuit HD SS or the PPG Concept, a little more money then some that were mentioned but worth it if boat will get any abuse.
The best of the best was Durathane (ppg) but I'm not sure its even made anymore.
Above water base clear is great and will last longer.