Weld repair to Aluminum Hull - foam and floor considerations

Waldguy

Cadet
Joined
Aug 18, 2006
Messages
7
My 16' 1998 Fisher Spectrum has been leaking since I got it in 2011. I filled the hull with water and found the leak - at the support of the front bunk.

I poked a hole in the floor. From what I can tell, the crack is near the stringer (I think that's the name of the longitudinal support). To complicate - there seems to be foam fill along the outside third of the hull. The crack seems to be in the foam section.

I'm prepared to chop a hole in the floor, but am unsure how big to make it and where to go from there. I think I have to make it big enough to remove the foam, weld, then replace foam and floor hatch. Anyone know these boats or what to do? I have zero experience with this. I do have a good aluminum welder lined up.

Any help or advice is much appreciated - from how to cut the hole, to removing the foam, to healing the cuts, to new foam or not!
 

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Waldguy

Cadet
Joined
Aug 18, 2006
Messages
7
Well, left to my own research, as the crack is limited, and I don't want to mess with all the foam, I will likely try a fill with JB Weld or, more likely, 3M 5200 from the outside only. If it doesn't work, not much lost.
 

chevymaher

Commander
Joined
Mar 29, 2017
Messages
2,914
Secret to JB Weld. No matter what they say is the drying time. 48 hours for a full cure so it isn't brittle.
 

Picky fisher

Cadet
Joined
Dec 30, 2018
Messages
17
Fixed a crack once in brothers boat by drilling each end so doesn't spread then 5200 it.put patch down then buck rivet patch make sure to 5200 rivets as they go in. His boat is still great takes a beat down from erie every year.
 

Grub54891

Vice Admiral
Joined
Jun 17, 2012
Messages
5,908
Calculate where the Crack is, on the inside. Drill a 6" hole with a holesaw, clear out the foam, go to a good aluminum welder and have it repaired. Replace the foam, add a deck plate.
 
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