My 14' jon boat has a crack in the center "ridge" right where the flat bottom bends up to form the bow. I believe it will need structural support as well as sealant to be fixed. (This part of the bow is dragged across a carpeted support when I trailer the boat. I suspect that may have caused the crack in the first place.)
I've read several recommended methods:
1) JB Weld. Heard this tends to crack, though.
2) JB Weld + patch. JB Weld leak, then put aluminum patch on top and JB Weld it on, too.
3) Pay a welder to weld it. I hear this should cost around $50?
4) Seal leak and affix aluminium patch with 3M brand "5200" polyurethane sealant.
I would not use jbweld on a crack like that. I can see jb weld for patching a tiny pin hole or something, but for this i would not use it. I personally would pay a welder to weld it. $50 is not that much money to have the job done well. You will need to take a wire wheel on a grinder and clean that area down to bare aluminum so the welder can make a good clean weld.
I agree. You might be able to get away with a JB type fix for a while, but it probably wouldn't last forever like a re-weld. However, if welding isn't an option, I would clean and prep the surfaces on both the inside and outside of the crack. You can then apply a "snake" of JB weld marine epoxy putty (there are other brands too) that is about 2 inches longer than the crack itself so that you have about and inch of overhang on either side. (The JB weld putty is a two-part epoxy that is activated when you knead it like bread dough, or play-doh.) I would then lay the "snake" and push it in to place very evenly. It should ooze out of the crack and come out of the bottom of the boat a bit, but that's ok. Once you've smoothed the snake out nicely form the inside I would then move to the outside and smooth out any of the JB weld that came through. I would then allow that to cure fully sand smooth, then apply a second "snake" on the outside of the crack and smooth it out and let cure. You'll then want to prime and paint the fully cured, and sanded JB repair. It may not last forever, but it may buy you a few more seasons and would only cost $20-$30, but if you can find an aluminum welder in your area they might be able to fix it for less than you think. Good luck. Keep us posted.