Sealer for pontoon.

horsefly60

Seaman Apprentice
Joined
Apr 3, 2018
Messages
36
What's the best below water level sealer for pontoon. No leaks just pitting at this point. Want to seal them before the summer.
 

stresspoint

Lieutenant Junior Grade
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Sep 19, 2022
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1,045
pitted aluminum is gonna be pitted aluminum , as a welder you would know that , putting a dodgy patch on a pitted area is only going to cover a issue "not fix it".

put some gloves on and smear a tube of 5200 over the area , it will seal but for how long ??????.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,073
Depends on the extent of the “pitting”.

If it’s light surface pitting you can just sand it down to clean metal with bronze wool and apply a “aluminum” sealer to minimize the rate of oxidation going forward.

I used the Woody Wax Tower Treatment system few years back to restore the supports of my hardtop. Worked great. I apply the included metal sealer once a year to maintain it

If you need a filler, there a numerous aluminum epoxies on the market. I’ve used Devcon in the past with good success

 

stresspoint

Lieutenant Junior Grade
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i think i would get to bottom m of the reason why its getting pitted before deciding how to deal with it , stray currents in a marina ???.
 

dingbat

Supreme Mariner
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Nov 20, 2001
Messages
16,073
Pitting corrosion is almost always atmospheric related
pH below 4 or above 9
Stagnate water (low O2) will do it every time
Salt is deadly to aluminum as the pitting of my hardtop demonstrates
 

stresspoint

Lieutenant Junior Grade
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Pitting corrosion is almost always atmospheric related
pH below 4 or above 9
Stagnate water (low O2) will do it every time
Salt is deadly to aluminum as the pitting of my hardtop demonstrates
lots of allycans down here in Australia, seen some pretty badly rotted boats from pitting .
Queensland up north was the worst ,where there is also humidity to exasperate the corrosion.
some owners of boats had people come out to check the voltages in the water at the marinas where some were moored, shallow brackish salt water.
stray currents and alloy boat are not a good mix ,but in saying that , its surprising fish don't get electrocuted up there .

op if the boat has started to pit then a cover up with a sealant such as 5200 is only going to last a short time if not treated first , even treated it does not last too much longer ,
finding the root cause will save the sealant from just being pushed off the hull as the reaction that is causing the corrosion continues.
iv seen it all before when people do patch up jobs just to sell a boat ( even done a couple myself for people that just want to stop the leaking) it just peels off and leaks again in a short time.
i know its a shitty situation having your boat rot away ,weld/ plate it up and be done if you are keeping the boat its the only safe way..
 
Last edited:

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,073
lots of allycans down here in Australia, seen some pretty badly rotted boats from pitting .
Queensland up north was the worst ,where there is also humidity to exasperate the corrosion.
some owners of boats had people come out to check the voltages in the water at the marinas where some were moored, shallow brackish salt water.
stray currents and alloy boat are not a good mix ,but in saying that , its surprising fish don't get electrocuted up there .
I agree with everything said, but let’s not conflate the causes.

While the most common cause of corrosion in lower drive units, stray current is not the cause, it’s the facilitator.

Galvanic corrosion requires dissimilar metals in contact or very close proximity to each other. In this scenrio, aggressive corrosion begins at the point of contact between the dissimilar metals and progresses from there.

In this case, one would assume the engineers did their job and isolated the aluminum pontoons from contact with dissimilar metals. Even if they connected the log to a ground source, the corrosion would have started at the point of contact with the ground cable and moved from there
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
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49,538
the aluminum is fastened with stainless hardware. the only thing that would be worse from a galvanic standpoint is if there was a copper washer bolted between.
 

airshot

Vice Admiral
Joined
Jul 22, 2008
Messages
5,080
In my area, folks have claimed good success with a product made by "goop" .....it is a sealer that is brushed on and has fibers in it that plug small cracks and pinholes. Reviews have been very good but not sure it has been out long enough to determine long term use. On my small Jon boat, the bottom has cracks and pinholes which I covered with a product called
" leak stopper". It is a clear roofing sealant available thru home despot and tractor supply. Coated both inside and outside of my beat up aluminum Jon boat. 8 years later, still no leaks. Can be brushed or rolled on.
 

horsefly60

Seaman Apprentice
Joined
Apr 3, 2018
Messages
36
Depends on the extent of the “pitting”.

If it’s light surface pitting you can just sand it down to clean metal with bronze wool and apply a “aluminum” sealer to minimize the rate of oxidation going forward.

I used the Woody Wax Tower Treatment system few years back to restore the supports of my hardtop. Worked great. I apply the included metal sealer once a year to maintain it

If you need a filler, there a numerous aluminum epoxies on the market. I’ve used Devcon in the past with good success

Ya just a aluminum sealer is all I need. But wanted opinions. I been working on boats over 50 years. Somehow a cadet on here. When 2 years ago I was a Admiral
 
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