bobocraft,
My first boat was a leaky 16' starcraft. Forget about any epoxy repairs. I tried most of them and they work for a short time (sometimes longer)but eventually, due to the constant movement of the alluminum, the repair seperates from the metal.
I found the best solutions is either welding the leak (tricky due to the thin gauge) or mechanically (replacing rivets) closing the hole. If you tap on a rivet, and it moves it needs to be reset or replaced. This is probably the cause of some of the leaks. Put a dab of silicon cement on each rivet before you replace or reset it as a gasket.
What I would do is when the leaks were getting out of hand is rip the deck up and on a dark night shine a light in the boat toward the deck. the light leaks will show.
Good luck,
