Reply With QuoteThere is no good reason to paint an ali tank. If you get corrosion it'll be from a galvanic reaction and paint is unlikely to prevent that.
Getting replacement tanks in my sharkcat in the next week or two, pulled the old stainless ones out and they were coated in a bit of epoxy resin, should I coat my new ally tanks in something to stop any possible corrosion ? I've heard of people glassing them or clear coat paint also. I was thinking possibly tectyl ? Keen to hear what you guys think.
There is no good reason to paint an ali tank. If you get corrosion it'll be from a galvanic reaction and paint is unlikely to prevent that.
I used gel coat on my ali tank.
Chris, are you saying that oxidisation, humidity and salt will not help to deteriorate a shiny new ally tank?
Having asked you that, I am about to pull a leaking (presume corroded) alum tank out of a 10yr old fibreglass boat. The autopsy will be interesting and will no doubt effect how I build and install its replacement.
Cheers, Pauly
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Actually the oxide of aluminium is very stable and you may well be better off not painting it. Any paint will probably get scratched in places and this can lead to corrosion starting. Also if it is sitting in water it will corrode. Your best bet is to make sure that the compartment is drained. I have also seen advice that you glue plastic strips to the bottom of the tank so that it doesn't sit in water.Originally Posted by Shark Poker
I have had two aluminium tanks corrode and crack (no I didn't follow all of the above advice). I am currently fitting a plastic tank from Sant Marine - a least I know it won't corrode!
I have often wondered how a tank coated in something like rhinocoat would go. The only issue I could see is if water got between the coating and the alloy.
It is more likely that the tank is leaking due to welds fatiguing over time than corrosion. Painting aluminium or Stainless stops the protective oxide forming on the surface. Assuming your new tanks are built to a suitable standard and are at least 4mm thick they'll last a long long time without painting.
Built heaps of tanks best thing to do is buzz the outer shell with orbital sander prior to assembly clean down after testing with decent thinner or acetone and paint with Joton Jotamastic 87 or similar with roller or large brush this should give years extra life to alloy tanks probably adds 100 bucks per tank but well worth it also remember fuel cell drainage if water can get in Cheers Rod
Have a look at KB coatings if you want to coat it with something.
My limited experience with ally tanks is that they leak due to corrosion caused by water, from the inside.
Oil floats on the surface of water in the same way that water sinks to the bottom of a fuel tank. If there was salt in the water, its more obvious.
We replaced a mates' tank recently (Quintrex from 1990's) and the holes were in the bottom of the tank. Not the welds. Also I saw the same problem on some tanks from a local ferry company.
Considering that old tanks look terrible when removed from under the floor after many years, this is a very reasonable question from the original post on this thread.
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There is a couple of plastic tanks that will fit in a sharkcat hull easily, I looked at them when I did mine, but couldn't find anyone here is Aus that was a supplier, and didn't want to go the import route.
My boat has a plastic Sante tank and it great after 10 yrs not sure they make them to fit a cat in particular but I would imagine they would have something to suit ..Matt
A bad days fishing has got to be better than any day at work......
Yes they do, there was two sizes that would fit in an 18' cat without any modifications.
Hey Lembo,
I have just finished up making my two tanks for my Shark Cat CC.
Mine are made out of some 5mm 5083 that I had left over from a previous build.
I haven't coated mine, but I do have a boat builder mate in the States that swears by using Coal Tar Epoxy on all his builds.
I bought some 6mm x 75mm Nitrile rubber that I will cut up into strips to put on the bottom of each tank, using 3M 5200 adhesive.
Mine will be bolted to each bulkhead, not foamed in. The fuel tank compartment will also drain into the hull.
Regards
Con
thanks for the input guys, I pulled the old tanks out and they were sitting on some bits of rubber with cross beams going over the top. also a bit of epoxy bog sticking it down.
the previous owner swore that the boat had 120 litre tanks in it, but after removing and measuring they are actually just under 180 litres, maybe 170/175.
the tanks are going into a fully sealed compartment, with the only access will be through a bulkhead with a bung, so I can drain it just in case. but it should stay dry, I know ally coated in paint can have dramas if moisture gets between paint and ally. that's why I was thinking a coal tar type stuff.
thanks for your ideas guys very helpful.
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