Rusting water tanks

[kiwikol]

Has anyone had experience of rusting steel water tanks and decided to line them with something other than paint? I don’t mind a bit of rust in the right places but it’s almost impossible to adequately prepare and paint inside a water tank, and when one side of it is actually the hull plating, it give me insomnia (like the rust suffers from!). I’m thinking of making up a prefabricated butynol liner or something similar but anticipate all sorts of problems with making connections between baffled areas, venting flanges etc. Has anyone regained their sleep with a solution?

 

[alan006]

Why not cut the top of the tank off. Treat and repair the inside of the tank and buy a flexible tank to sit inside the old tank.
This way there is the minimum alteration to your exsisting pipework as well.
Hope this helps.

 

[Billjratt]

And it would let you have a look at the inside of the hull plating as well....

 

[oldsaltoz]

Cutting out the top of the tank and fitting a liner, plastic tank or flexible tank may not solve the problem as condensate forms between the liner and hull.

If you decide to follow this line I would install an insulation layer and a breather gap to avoid condensation.

A self contained plastic tank that will not contact the hull might be OK, but you would need to drill some drain holes in the bottom or lower edge of the old steel tank.

Hope this helps.

Avagoodweekend......

 

[kiwikol]

Mmmm! The question of condensate is an interesting one. Elsewhere in the boat I have installed polystyrene insulation against the hull plating, carefully snug fitted but removable, the theory being ‘no air space, so no water, so no condensation’. Later inspection has proved this to be substantially correct as I have never found any condensation when sections have been removed for examination and the paint has not deteriorated. A breather gap I believe would actually allow air (and therefore water vapour) to reach the cold surfaces and condense (unless sufficient air circulation to allow evaporation).
My tanks are somewhat trapezoidal in section and so a purpose made shape would be necessary and I was thinking a rubber liner would be more accommodating to irregularities. I would obviously have them (fairly) easily removable for annual inspection of the hull (to reduce my insomnia).
Oh, and if I drill holes in the bottom of the old tank I would sink! Well, that would solve my problem I suppose!!
Thanks for your comments guys.