i used a similar product made by hobart on my flatbottom this past week... it actually said "for aluminum boats" on the package. i used a mapp gas torch to heat the base metal and then used it to melt the rod. after i let it cool i actually stabbed it with a flathead screwdriver and then hit it with a rubber mallet a couple of times and it didnt budge a bit! i havent tested it on the water yet but ill be coating the inside of the 5 inch gash i patched with 3m 5200 sealant so it will be watertight.