Useful Life - Steel Diesel Tanks?

[cekramer]

I am considering purchasing a 1972 Moody with two steel diesel fuel tanks, my question is what is the useful life of such tank material? Not stainless steel.

Thanks for any opinions.

Chuck

[speedoo]

To give you an idea, a lot of Kelly Peterson 44's were built in the late 70's with "black iron" diesel tanks. My understanding is that many, if not most of those tanks have now developed leaks and have required replacement.

I assume "black iron" is similar to non-stainless steel.

[Cheechako]

Black Iron would be preferable to steel reportedly. Stainless steel in the bilge can be really bad. I bought a 1985 boat in 1992 with three tanks.. one in the bilge. I started to fill the bilge tank after I purchased the boat, while I was pumping suddenly a question entered my head "why was that tank completely empty...?" I stopped and checked the bilge... 2" of diesel! The tank was removed and it had two holes, one about as big as a pencil eraser..... right where it sat on a fibreglass support beam (lack of oxygen) an older boat with metal tanks or any sort in the bilge will likely develop problems at some point....

[DeepFrz]

The length of life of your tanks depends entirely on how well they were built, how well they were mounted and how well they have been looked after. But they are getting a little long in the tooth if they are the original tanks.

I think you will have to consider that they are past their usable life and then after inspection if they are still good, consider that gravy.

[forsailbyowner]

My 1976 morgan outIsland has original steel tank. 5 yrs mine no problems yet. Owners manual describes as aluminized steel, whatever that means.
Steve

[clockwork orange]

Have a really good look to see whats involved to replace them,if its going to be a huge job you may want to pass on the boat because its only a matter of time before they start leaking. I once replaced a iron fuel tank on a Grand banks 42 trawler woodie, i was actually replacing some stove in planks on the bottom when i noticed they were saturated with diesel, i took some planks off and found that the tank was shaped to get maximum volume so had a definate low corner which had rusted through from the inside where water had laid there,there was absolutly no way to get it out without removing a lot of stuff so i removed it from the bottom,fortunatly i was working there anyway.
We have 2 boats in the shop right now with leaking diesel tanks,both of them with aluminum tanks in the bilge, so they are probably no better, both of these boats have no provision for removal,in fact the Cherubini 44 had the engine on top of it which had to be removed. Each of these tanks will cost at least $8000 to replace because of a lack of forethought.
Steve

[redcobra]

Just repowering a 1975 Pearson with a painted steel tank. After removing the engine (old) and looking at the tank (round and painted red) and although it didn't look TOO bad I decided to replace it as replacing it meant either removing the engine or cutting into the cockpit sole. After it was out and I inspected it in the light, boy was I glad. Several rusting spots that were slightly soft were in areas that couldn't be seen until removal. It was the original 1975 tank.

New tank came (in 7 days) from a place in NJ. Square epoxy coated aluminum. Impervious to Biodiesel etc. The marina has constructed a square fiberglass tray for it to sit in, and for the first time in 5 boats.....I'm gonna have a FUEL GAUGE.
Hooray..., no more yardstick stick down the fuel inlet.

[speedoo]

hey redcobra... could you post the info on that place in NJ? And I'd be very interested in hearing your thoughts on why you went with them. I'll be replacing some tanks soon.

[Evan]

20 - 25 years is about all you can expect for a painted steel tank (black iron = mild steel). Less if there is water on the bottom of the fuel or if the exterior gets wet too often.

Aluminumized steel is steel coated with an aluminum paint. Good for corrosion resistance.

[redcobra]

I don't know the name of the place. You can call Connie Markley at Markley's Marina in Essex MD and ask her. It's where they get the tanks for the work boats they build.

[speedoo]

Originally Posted by redcobra

I don't know the name of the place. You can call Connie Markley at Markley's Marina in Essex MD and ask her. It's where they get the tanks for the work boats they build.

Thanks, just spoke to Connie. It's Atlantic Coastal Welding in Bayville, NJ.

SpeedyTanks.com: ACW Marine Fuel Tank Fabrication Experts

I'll be calling them soon.

What made you go with aluminum (vs. mild steel) and would you mind telling me what your cost was and the tank size?

Thanks.

[Cheechako]

Any tank (steel, alum, stainless) that is in the bilge, gets wet, and has a support or something in contact with it where the water can just sit in contact with the tank will have problems eventually. For that reason I replaced the one I mentioned above with a tank made of Titanium. (lucky me, I ran an aircraft fabrication shop at the time!) More recently for an aluminum boat builder using a complicated V bottom tank, I was paying about $7 per gallon tank size for ABYC certified Aluminum tanks. (80-145 gal tanks) I would think a cube or rectangle might be less, but a one off might not be I suppose...

[Pblais]

We have all stainless tanks. They do however have the ability to be removed easily. With enough cursing I think I could pull all three in less than a day with a little help just doing the lifting up the companion way. They we made to be installed after the boat was built. Nothing destructive is required.

You get into some of the older Allieds like the Sea wind and removing the tank is major surgury. You have to rip up the 1 inch teak soles to get so you can even see them. Some are impractical to remove. You end up leaving them and using up lazerette space for new tanks.

If you can get the old tank out with some effort then at least it could be done if you had to.

[speedoo]

Originally Posted by Cheechako

Any tank (steel, alum, stainless) that is in the bilge, gets wet, and has a support or something in contact with it where the water can just sit in contact with the tank will have problems eventually. ...

OK, if this is true (and I have no reason to doubt you) then the choice for a durable tank that is close to the bilge would be plastic. But plastic tanks cannot include baffles so if I need a water tank that is about 6 feet long, I would have to go with two three foot long tanks to get a baffle effect.

On my boat the water tanks are under the cabin sole, very close to the bilge, and replacing them is a huge job. The fuel tanks are much more accessible... at least one of them is. So I may go with aluminum or black iron for the new fuel tanks, and plastic (Ronco) for the water tanks.

Does that make sense?

[redcobra]

Regarding water and aluminum tanks, this should be read:
Boats, Yacht: How to Install an Aluminum Fuel Tank

My tank is a 34 gallon tank and I don't know the cost as I haven't gotten the final bill from the yard yet. They did build a glassed in tray with drain holes and the tank on slats as per the builders instructions (see link above). The baffles seem to work well also as there is very little sloshing when I was rail down at 7.2 knots in 15-18 knots with gusts to 25

She moves like a freight train under sail with the new rigging and sails, and the new diesel gets me 7.3 knots at 2700 rpm with the new 3 blade maxprop, even dead into 15 knots of wind (wind instrument was reading 22-25 knots and boat speed was 7+).
And, IT BACKS UP!