Does alum boat seam filler shrink and swell in old boats?

[docksider]

There is that (usually black) material along major rivetted seams in most aluminum boats. In older boats, to what degree does that shrink when dry for a long time and swell shut when placed in the water. It seems I've noticed a bit of that temporary leaking in one of my old boats, all of which are leak free once left in the water for the season.

I just bought a 1963 mirrocraft that appears to be in great shape and which was professed to be leak free, but leaks a bit at a seam near the bottom of the bow/stem plate and a bit at a side seam near the waterline (below when I'm in the boat). I'm wondering whether to wait and see, goop it with 5200, or return the boat. When I asked a local dealer to confirm my impression that some leaks seem to be due to this dried out seam material, I was told "no, that doesn't happen as far as I've ever seen."

Do any of you know more about this topic?

Thanks!

 

[Bondo]

Re: Does alum boat seam filler shrink and swell in old boats?

Ayuh,.... The ole seam weltin' will shrink with time,...

I kinda doubt it ever expands... more likely, the leak fills with crud...

Btw,... 5200 isn't the stuff to use to fix it,...

Google Glu-vit... a Much Better product for the task at hand...

 

[docksider]

Re: Does alum boat seam filler shrink and swell in old boats?

I guess I've been lucky with earlier boats-- either no leaks or crud in all the right places. This mirrocraft is otherwise very nice and probably worth sealing up. I've heard about Glu-vit. I'll look into it. (Might have to decide whether to stick it in the water long enough to see if crud comes to the rescue again or just get on with something more official.)

 

[64osby]

Re: Does alum boat seam filler shrink and swell in old boats?

There is also Coat-It, same kind of stuff as Glu-vit just less expensive that some have used here.

I have a 63 Lone Star and it has a black filler strip in the seams, rubber made by Goodyear from what I've read. Leaked like screen door. Did the Glu-vit and all is clean and dry.

 

[docksider]

Re: Does alum boat seam filler shrink and swell in old boats?

Thanks for the reply and the info about the rubber (goodyear) and "Coat-it". It's helpful. I've ordered some Gluvit. Part of me is temped to stick it in the water for a few days to see if the leaking is self-limiting. I'm surprised so few have weighed in on that phenomenon. Thanks again.