SlimeTime, the seams have a sealant strip in them, at least 1/16" thick, 3/8" wide of something that would have to be all cleaned out before I could weld it together. And to get a good weld on the old metal, both surfaces need to be cleaned with a stainless wire wheel. I would do better pulling a pattern off this boat and starting with some new sheet metal.
I hope I just need to replace the messed up sealant - and there's some really obvious bad spots - then paint the bottom inside and out. The water was in the boat for about 1 1/2 hours, maybe there was some condensation but I did see water seeping through the seam sealant in a couple bad spots. It's really only coming through maybe 5-6 spots in the front and both rear corners just a little. Once the water got on the outside, it ran towards the back of the boat dripping the whole way.