I did take a close look at the bottom of the boat when I bought it and a few times more when I floated it looking for leaks and installed the new trailer bunks. I didn't notice any cracks between the rivets. I was aware of the issue as it was noted by several other threads on here during my research. I think that it has been relatively lightly used from the condition of most of the hull. This boat has transferred hands several times, as close as I can tell from the ghosts of old reg numbers on the hull, I'm at least the 4th owner.
I don't think that you would suffer any weld quality issues if you only welded from the outside, but I'd be really concerned about any of the foam igniting. If you got the old waterlogged stuff in there, you will probably be ok, but I wouldn't chance it. There aren't many places in the bottom panel of the hull that are more than 1" away from some kind of foam, and aluminum loves to spread the heat around.
I'm not sure how significant your cracks are, but would you be better looking at something like Steelflex? The likely hood of visually finding all of the smaller cracks visually isn't very good, so you'll probably be constantly chasing them as they continue to show up.
Good Luck!
I don't think that you would suffer any weld quality issues if you only welded from the outside, but I'd be really concerned about any of the foam igniting. If you got the old waterlogged stuff in there, you will probably be ok, but I wouldn't chance it. There aren't many places in the bottom panel of the hull that are more than 1" away from some kind of foam, and aluminum loves to spread the heat around.
I'm not sure how significant your cracks are, but would you be better looking at something like Steelflex? The likely hood of visually finding all of the smaller cracks visually isn't very good, so you'll probably be constantly chasing them as they continue to show up.
Good Luck!