Rust on fuel tank

I have a 1979 Californian 34. My fuel tanks are showing rust on the outside but not leaking. Any suggestions on what to put on them to stop the rust and to seal them?
Thank you

New decks above them.

pete

96commander said:

I have a 1979 Californian 34. My fuel tanks are showing rust on the outside but not leaking. Any suggestions on what to put on them to stop the rust and to seal them?
Thank you

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POR 15 has a kit that I used to coat the top of my fuel tanks. I purchased the kit from Eastwood.
They had a lot of rust in the area that was adjacent to the air intake vent. But after scraping off the scale/rust it was still sounding solid.
The kit is 3 part. A cleaner, and etch, and a sealer.
You'll need a respirator when you apply the sealer.
All in all it was a pretty easy job once I cut out the luan to get access to the tank. Just a little messy.
Hope this helps

Much appreciated! Thank you

POR 15 is good stuff but a PITA to do. The results are very nice though. I used some on my boat yesterday.

I used it on a motorhome battery tray / compartment and really like the stuff. Only warning is it is very hard to keep a partial can. They sell multi packs of small qty.

Rust on tanks means moisture. Were did the moisture come from? Then the big questions, are any of the 6 sides of the tank up against a wall and how will you deal with that side?

With so little info it is really hard to advise you on how to proceed.

If yours is like mine, one of the weak points in the 34 design is that the shaft logs are immediately underneath the fuel tanks. I have PSS seals and while they are dry for the most part, they do put out a small spray of salt water which then contacts the bottom of the tank. I had surface rust as well on my starboard tank and used the POR-15 system to paint and treat that area. So far, it has worked very well.

Luckily, I can see all of the sides of the tank and the tops and sides of my tank do not have any rust issues.

I say “tank” because a previous owner replaced the port side tank with aluminum but the starboard side is still original steel.

I ordered the three parts (cleaner, metal prep, and POR-15) from Amazon. As has been stated, the paint does not last long after you open a can so I ordered the six pack of the small cans so I can use one at a time. The unused ones, I store in the refrigerator which is supposed to help with shelf life.

I'm going to try Coroseal cleaner and primer on mine, and I might finish with a top coat if I'm feeling fancy. The rust in my case is on the top of the tank, from water intrusion at the fuel fill fitting, which needs to be re-bedded as well.

tiltrider1 said:

Rust on tanks means moisture. Were did the moisture come from? Then the big questions, are any of the 6 sides of the tank up against a wall and how will you deal with that side?
.

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In MY case the tanks had a space behind them and I got creative with a small diameter paint roller on a stick and was able to coat about halfway down the outside.
And yes, I don't really know how must rust was on the outside.
(But it's no longer my problem)

Early in my trawler ownership I noted rust on the tank tops, outboard surfaces (yes, I could actually reach around between hull and tank), and near the shaft seals, as was already mentioned. I scraped and/or sanded as best I could and then rolled on acidic rust killer like Ospho before top coating. There was some limited access to the bottom sides too. For the tops and outboard sides where I would not often be inspecting, I sprayed on fogging oil to finish off. The original steel tanks were still fine when I sold the 1972 boat in 2015.