Also, the tanks sit strapped to benches in the compartment so they are exposed on all sides except the bottom.  I've noticed that when they are full they sweat pretty bad and was wondering if I shouldn't put some type of matting underneath them to prevent moisture build-up. 

 Thanks for any advice.

2932 WESTFIELD ROAD

GULF BREEZE FL. 32563

850 934 8609/554 6172

Jim

"From birth, man carries the weight of gravity on his shoulders. He is bolted to Earth. But man has only to sink beneath the surface and he is free."
-Jacques Yves Cousteau,

As far as putting anything under them, upon reflection, I guess that since they have been in the boat or 23 years and the limited amount of pitting that I'm seeing now is all that has occurred over that period, I'll probably just put them back in the way they were installed by the mfgr. Apart from the bottoms the rest of the tanks are in great shape, just dirty from 23 years of dust and grime.

Thanks for ya'll help.

 I am one of those people that can NEVER pull off a shortcut without having it come back and bite me in the butt at a later time.

 if this was my project and I knew that the tank  was compromised as described and chose to smear bondo / jb weld / fiberglass /undrecoaring or any other quick fix that sounded like it will prevent what I already know is gonna happen anyway, I wound just have to adjust My priorities to do the long term fix rather than have the unexpected shutdown the nite before the big fishing event or cruise of a lifetime or try to explain away the "I think I smell gas feeling" that will come up at some point in the future. ( my luck would have it start leaking abought the time I decide to sell it and I would be looking at tearing the tank out and doing all of this in order to make the boat sellable)

 Hopefully whatever you decide will work out. Good luck

 EDIT///Slow typing and eating a sandwich strikes again/ sounds like you have everything under control

WOW!!!!! WHAT A RIDE.

After you have it repaired, I would entertain having the entire tank Rhino lined on the outside. It will isolate contact with everything that might cause more bad spots or wear spots including moisture from sweating. And it will be a little bit insulated and corrosion will be less likely too.

Pictures

http://www.forumpictureprocessor.com/pictureprocessor/galleries/usergallery.asp?gallery=1238

I'd probably fiberglass at least the bottom of the tank if it showed pitting. Couldn't hurt.

Jim

Crap!!!  Luckily mine ain't nowhere near that bad. 

Actually, after scrubbing them off with some a scouring pad, it turns out that some of the areas that I thought were corrosion were actually "mineral" deposits that, once removed, exposed solid un-affected metal underneath. These deposits must have been calcium based because the vinegar wash that Sealark suggested went to town on them.

There was only one spot about the size of a dime on the port tank that actually had pitting and that was only about 1/16" deep on 1/4" thick aluminium.  I like the rhino lining idea unless there is a good reason not to go that route. 

Thanks again for ya'lls help.

You could do the hillbilly redneck thing and smear the tank with some really sticky, thick, high temp grease or even spray it with tar that has been mixed with gasoline in order to spray it. The gasoline will evaporate and leave a tar skin behind.

It will smell for a few weeks but the tank will no longer corrode or accumulate mineral deposits.

"From birth, man carries the weight of gravity on his shoulders. He is bolted to Earth. But man has only to sink beneath the surface and he is free."
-Jacques Yves Cousteau,