30 year old black steel fuel tanks

Had my GB 42' fuel tanks cleaned today. Was concerned because they are 30 years old and as everyone is aware not easily or cheaply replaced. Seem to be in excellent shape for their age according to my tank guy. I snapped these pics just for the record but not sure what anyone can really tell from them. Seams are good, no flaking in the bottom and no water in fuel. Actually, very minimal gunk in the bottoms as well. I can't find any hint or record of them being cleaned in the past and I have a gazillion receipts back to when it was a new boat. I assume I should just consider myself one of the lucky ones.

Very nice tanks. Look new

What did that cost you...ballpark figure?

$830. Polished/filtered 300 gallons of fuel as it was pumped into storage tanks. Opened the inspection ports and used a vacuum and pressure "washer" of sorts to clean and blow the gunk that was there into the open area where it was sucked out. Wanded through the baffles and inspected with a scope. New inspection plate gaskets put on and then the fuel was refiltered as it went back into the tanks. Took about 7 hours. He did add a quart of FPPF Marine Diesel Treatment which he swears by. I believe it is more for water dispersion than it is a biocide to deter growth.

Nice...what a good feeling to get that confirmation! Money well spent. I can only hope for similar results with my new-to-me 40+ year old boat....

My 1986 GB 42 tanks rusted through from the outside. The tanks were set on neoprene pads under the tank corners where water (condensation, etc.) can collect unseen. After 29 years, they were replaced.

All I can say is yuck. I sat there all days when they were doing it wondering if I had a $20K bill in my future. Mine look great from the outside and I can scope the top to check for water on top which, from what I have repeatedly read, is the #1 killer or so it seems. Can't get under the bottoms so haven't a clue. The tops of mine are smooth and clean. The tanks are painted a gloss black but it appears to be an all over painting and not something that someone did to make it pretty and the paint is not particularly new. I say they are 30 years old but I guess it is possible they were replaced in the past. would have to sometime between 1997 and 2012. I know the guy I bought the boat from and I have been in touch with the original purchaser so I know what went on with them. The middle guy...haven't a clue.

I will say that the best thing about my boat is that all but 4 of it's 30 years was spent up on the Great Lakes where it was out of the water 8-9 months of the year and under cover. The teak decks show that more than anything. Being out of the elements slowed down the aging process tremendously.

In my experience tanks fail when water can get underneath but not air. The water causes the tank to corrode and pit until finally the tank develops a leak. There are two things you can do. One is to have the inside of the tank coated. Felix Marine has a process for this. The other is to wait until the tank leaks. Felix Marine has a process for this as well.

Should your diesel tank leak I would contact Felix Marine before I spent 10-20k on new tanks.

Great deal and great tanks. Someone here charges $1 per liter for polishing. Not only do you have clean tanks, and fuel, you look to have good tanks. Must be a big relief.

Now just keep the Outside dry and you will get another 30 years.

I think I check for moisture on top of the tanks as much as a I check my oil. I read a lot about the seal of the deck fill plate going bad. How do I replace that? Assume it is from the top, form the deck. Does it unscrew and have a simple gasket underneath? Right now they don't leak so I am leery of doing any get ahead of the problem preventative maintenance....

A pleasant surprise to find 30 year old tanks in new condition!
I replaced mine due to external corrosion on the bottom of the tanks. Now they sit on spacers to allow air circulation on all sides.

Most fill plates are screwed to the deck and have a hose tail fitting below. To replace the gasket, just remove screws and loosen the the (usually hard to access) hose clamp. Then pry up the deck fitting.
I used butyl tape to re-seal the deck fittings. Make sure the hose clamp is tightened well, or any deck leak will trickle into the tank rather than onto it.

tiltrider1 said:

In my experience tanks fail when water can get underneath but not air. The water causes the tank to corrode and pit until finally the tank develops a leak. There are two things you can do. One is to have the inside of the tank coated. Felix Marine has a process for this. The other is to wait until the tank leaks. Felix Marine has a process for this as well.

Should your diesel tank leak I would contact Felix Marine before I spent 10-20k on new tanks.

Click to expand...

My 30 year old tanks are not as nice as the OP..... just had mine cleaned and found some top rust and a small leak that I can’t see the source. The tank removal is scheduled this week. I’m curious about the repair claims... local Felix Marine repairs Electrical issues and equipment Installation not tanks or mechanical issues.

Here is what you don't want to find!

I replaced mine w new aluminum 12 years ago.
One was leaking. Decomissioned years befor that.

Contact the Felix Marine people in Seattle. They should be able to hook you up with some one local.

I have heard from many a happy customer recommending the process.

Awesome. My 40 year old sailboat also has black iron fuel tank is excellent condition. I've always tried to keep her pretty full to minimize corrosion. I spot blasted the exterior 25 years ago and covered it with coal tar epoxy. Still good as new.

I'm more worried about my fiberglass tanks on Last Tango, 1980 Ocean Yachts 49+2 Trawler.

Great thread, Firstbase. Thanks for sharing.

You are welcome. To say I am relieved is a huge understatement.

I have no comparison but the price seems very reasonable for what was done.
Nice job

Before I called the company I searched around and it seemed like $700-$900 was the cost range stated by others and what I was sort of prepared for. When I spoke to the guy over the phone he estimated it at about $800 but that could be higher depending on what was found. I had about 300 gallons total in the two tanks which was polished. Had they been full it would have taken more time and I'm sure the cost would have been somewhat higher.

I really appreciated that he explained and showed me everything. Inspection port gaskets (old ones were bad and he made new ones out of neoprene), inside the tanks after he opened them and after cleaning, the filters showing what came out of the fuel, even the inside of the tanks he was using to temporarily store the fuel while he was cleaning the fuel tanks. Oh, and when he made the gaskets he made a donut not just a big round circle of neoprene. He explained why but can't remember really. Anyway, he gave me the circles of neoprene he cut out in case I needed then for something else. Not a big deal but nice of him.

All told, not sure what I could ask more of him.