Not to beat a dead horse, but that np2 is paintable too.
I used to have a welding service, my canoe was flipped over behind my scrap bin (not a good idea). I asked one of my son's to unload the scrap from my truck. He thought it a good idea to throw the scrap metal into the bin, from like 10 yards. Needless to say a short piece of 7/8 bar stock found it's way to the side of my 20 year old canoe. It did not punch a 7/8 hole, but it did make a large 1/2 moon gash in the side. A nice dab of this goop and it was fixed, until the tornado wrapped it around a tree a few years later,
If I had leaky rivets I would get a tube of this stuff, flip the boat over now and cover every rivet, I would do the leading edge weld on the bow, I have rewelded several of them, they seem prone to wear and leaks.
Sorry to obsess over your leaky boat but this stuff just works so well. It seems to last forever.