Aluminum intergrated fresh water tanks

Hello, I am a newbe and would like your expertise on how to remedy cleaning integrated fresh water tanks that restricts access to all parts. I'm sure this isn't new in boat owner circles, but as opposed to ripping out all subfloors and cutting new inspection holes,(don't forget this is a totally aluminum boat) there's got to be a better way. The problem inside of these two tanks, which are baffled and conected from each side of the vessel, is the potable paint which is popping off from age (1988 vintage). I would say both tanks included, hold roughly 200 gallons on fresh water. I have cleaned what I could. Now, I need remedies without the total dismantling process. My first idea would be connecting charcoal filters to each outlet. Any other suggestions other than selling the boat would be appreciated!

 

If you can't access all parts, you also have no means to gauge whether there are areas which are in need of repair too. This is not an ideal situation. If your only method to fully inspect is to remove and cut inspection ports then that is what I would recommend. All areas of a tank/boat must be designed/made for easy viewing, for obvious reasons. If you can't you're playing russian roulette with the structural integrity.

NO!!!...this will eat the aluminium. Graphite/Carbon is high up on the reactivity series as the electrical potential is huge and shall eat aluminium very quickly!

 

If the problem is flakes of paint, you want a regular filter, not a charcoal filter. If it's cleaning and keeping the tank from further deterioration, then I think you want to avoid chlorine and put a magnesium anode in it.

 

Flaking paint is a sign of corrosion. If by integrated you mean they use part of the hull structure as tanks, it would be really wise to cut access ports to check for deterioration of the plating and framing.

 

Flaking paint

Hi Gonzo, thanks for the reply. I don't see a corrosion issue but believe it to be failed adhesion from age or metal not prepared properly. The flakes are large and in various sizes. After twenty plus years paint submerged usually has met its match. I don't see any signs of leakage on the outside of the hull. I really believe it is a paint issue and would rather avoid cutting if possible. The standing remaining water is clear and shows no signs of contamination.

 

Thank you Ad Hoc for that information. I am aware of the sensitivity of dissimiliar metals with aluminum but really dropped the ball on that one! Maybe a better approach would locate any type of filter outside the tank? And while your into this, what's your response to coating the entire tank inside with Portland cement? Seems I heard of this approach but don't know much about the aluminum factor it would have. I appreciate anyone's input on this. Thank you all.

 

Aluminum and alkaline substances (like concrete) are a bad mix.

 

Thanks for the information!!

 

We sandblast the inside of tanks on small metal vessels.

Leave the tank tops bolted on.

Cut access ports in the metal hull skin , between frames, then sandblast the inside of the tanks from the outside of the hull. Two holes are needed...one for the blaster to work thru..one for exhaust and utilities like lighting

Once blasted the tanks are immediatly painted...

The hull plate tank access ports are welded up..the tank top access plate is removed and the bare metal plate is prepped mechanically with grinders and painted.

Dont try to blast from the top down..you will make a mess and do a poor job

. Cut a hole thru the hull and work from the outside