richg99
Well-known member
For anyone STILL not convinced Pressure Treated wood is an issue with an aluminum boat.
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http://www.bbcboards.net/showthread.php?t=1017797
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http://www.bbcboards.net/showthread.php?t=1017797
TinBoats.net
The original aluminum boat site!
For anyone STILL not convinced Pressure Treated wood is an issue with an aluminum boat.
- Thread starter richg99
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Well yes, but not so fast ... as UNcoated wood cores can cause the same corrosion issue!
YES - PT will corrode tin; it is a well known fact.
YES - Use of stainless steel fasteners in aluminum will cause the tin to lose electrons to the SS, a more 'noble' metal, i.e., galvanic corrosion.
BUT - In the picture shown, the corroded holes are not located where the SS bolts are. This looks exactly like the transom on my Starcraft where I had to replace both the inside & outside transom skins. In that case, it was not PT wood that caused the problem, but UNtreated wood with any non-corroding coating on it ... i.e., bare plywood. This was confirmed with a phonecall to Starcraft Tech Support. Lund also used 'bare plywood' for a few years there, as I've seen this more on Lunds than any other brand.
Bare, uncoated plywood is bad as it WILL get wet and that damp wood sits against tin. Yes, galvanic corrosion will build up in the hull due to dissimilar metals, but if wet - and worse, if left wet with saltwater - then the tin can corrode from the dampness, regardless of any SS hardware to tin effect.
Summary - A boat with a transom of non-PT wood that is UNcoated wood, can suffer the same fate as pictured. Coat any wood core materials used with epoxy or that Old Timers spar varnish treatment (which I opine is inferior, but that's another topic of discussion).
I myself have only seen transoms like these on boats known or confirmed to have been immersed in saltwater, even once ... where a tall stern wave wet the transom core.
YES - PT will corrode tin; it is a well known fact.
YES - Use of stainless steel fasteners in aluminum will cause the tin to lose electrons to the SS, a more 'noble' metal, i.e., galvanic corrosion.
BUT - In the picture shown, the corroded holes are not located where the SS bolts are. This looks exactly like the transom on my Starcraft where I had to replace both the inside & outside transom skins. In that case, it was not PT wood that caused the problem, but UNtreated wood with any non-corroding coating on it ... i.e., bare plywood. This was confirmed with a phonecall to Starcraft Tech Support. Lund also used 'bare plywood' for a few years there, as I've seen this more on Lunds than any other brand.
Bare, uncoated plywood is bad as it WILL get wet and that damp wood sits against tin. Yes, galvanic corrosion will build up in the hull due to dissimilar metals, but if wet - and worse, if left wet with saltwater - then the tin can corrode from the dampness, regardless of any SS hardware to tin effect.
Summary - A boat with a transom of non-PT wood that is UNcoated wood, can suffer the same fate as pictured. Coat any wood core materials used with epoxy or that Old Timers spar varnish treatment (which I opine is inferior, but that's another topic of discussion).
I myself have only seen transoms like these on boats known or confirmed to have been immersed in saltwater, even once ... where a tall stern wave wet the transom core.
onthewater102
Well-known member
There is a rubber washer on each SS bolt head pictured there...easier to see in the larger original pictures. Amazing what a $0.20 part will save you in the long run...
The boat looks like it also spent a lot of time in the water, probably next to a dock. I'm also betting there was always enough water in the boat that the transom wood was always wet. If aluminum is always wet and there is just enough air flow, the aluminum will oxidize. I fixed a boat for a client who purchased an old Duracraft to restore and the previous owner had filled underneath the floor boards with poured in liquid foam and it was always wet and the pitting was horrible and there was no wood in contact and no stainless either.
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