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Island Time

Alloy Boats and Water Tanks

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Yes correct for the inside of the tank IT. But if the tank has sat on something conductive and saltwater has managed to get between the two,(because it's a boat and the tank is in a bilge area)  then pitting could have taken place. However, this is a localised problem between just that area of tank and whatever the other part was that it sat on. Earthing would not solve the problem. Even possible that is could worsen the problem. Check what the tank has been sat on. One of the biggest mistakes made is treated timber. I would isolate the tank by sitting it on some thin rubber or plastic. Even a simple line of silicon or sealant, then allow to dry, then fit tank.
Basically, this kind of corrosion is galvanic corrosion. Isolation being best remedy. The other kind is electrolytic corrosion and that is usually solved by earthing.

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Just to be that guy, Electrolysis doesn't require salt water - Any water really will start it unless it's pure water, Pure water is used to clean power lines as it doesn't conduct electricity but even slight contamination will allow a electricity to pass causing the corrosion to start/continue.


Wheel's, Is the treated timber comment something specific? 3 gin's down and cant figure it out :P



Here's some guys cleaning power lines

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Thanks "that guy". ;-)
Yes the treating chemicals used in most (there will be exceptions of course) Timber treatments, are often Copper and Arsenic. It depends on grade as to what and how much of course.
I learned this by an example about 30yrs ago, when a guy next door was working on his runabout. He had a piece of treated timber across the stern as a spacer that his outboard was clamped to. He had removed the outboard and not actually sure why, but also removed the timber. Underneath, the Aluminium transom had almost completely eaten away. Holes like Swiss cheese. And that day I learned all about Timber treatments and what was in them.

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Miss NZ

Yes I do know as I had company building alloy yachts in nz since 85

Stopped in 2000

I used Intenational Paints tank liner

No failures

Simply I sanded the tank plating before fabrication

The acid washed then painted iton

Search millennium 55 sailing my last build on youtube


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