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"Aluminium boat trailer flaking / disintegrating"
September 13, 2016
Q. My question and issue is with a large heavy duty boat trailer. The aluminium rails used to build it are from a semi truck. There are some areas on the rails that are literally flaking off. Some area's swell up and crumble away. Its similar to a piece of OSB plywood that's been saturated in water.
The trailer has only been used in salt water 6 times and thoroughly rinsed off.
There are steel axles and the tongue framework is steel, but this is not the affected areas. I have included pictures to show affected areas.
The trailer was like this when I purchased, but I need to know how to stop it please.
Any suggestions or a product to use, would be greatly appreciated.
Boater - Olympia, Washington, USA
A. Hi Paul. The bad news is that this sounds like an old aluminum outboard motor I had which just crumbled away. There were areas that looked halfway between aluminum and what an aluminum colored sugar cube would look like. And it had zero structural integrity; you could just break pieces off with your fingers.
A trailer with no structural integrity sounds dangerous, so I'd suggest that you have it lightly sandblasted to see how much sound metal you actually have left. Alternately you could just blast it with a pressure washer and see what happens. But there's really no sense trying to fool yourself about how much worthwhile aluminum is still there, or trying to encapsulate porous powdery aluminum into a clear coat to pretend it's still aluminum.
After you've blasted or pressure washed it, you could try treating with a "salt remover", then clear coating it.
I don't know whether this happens because of the aluminum sitting for prolonged periods in salt water, or from galvanic corrosion of the aluminum caused by contact with the steel because I also bought my motor many years old, but my guess is that the aluminum on your trailer was in terrible shape long before you bought it.
Ted Mooney, P.E. RET
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