I'll second the epoxy sealer. Was getting little pin holes in my 14' aluminun. After giving it two thick coats of the sealent, there has been no leaks since. If I remember right, it was a marine sealer that you can find at marien supply stores.
_________________________
They say that the man that gets a Ph.D. is the smart one. But I think that the man that learns how to get paid to fish is the smarter one.