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Old 07-09-2012, 11:35 PM   #1
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Fuel tank steel thickness

I have flaking rust on the bottom of my lateral fuel tanks, but no idea how big an issue it is. As far as I can tell there are no inspection ports anywhere to help with assessment, although I suspect rust issue is mostly an 'outside to inside' issue.

I'm told that knowing the original thickness of the black iron that the tanks were made of will help assess the issue. Has anyone removed/replaced tanks, or know someone who has done this AND knows what the original steel gauge was?
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Old 09-01-2012, 10:15 PM   #2
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I now have 5" inspection ports, one in the side of each tank. I think there are two baffles, so I can only see 1/3 of each tank - aft end of one and fwd end of the other. The wasn't much water at all in the tanks, but some crud on the bottom that is pretty hard - 'dead bug concrete'? I don't think it will come out easily, and getting an 2 more inspection ports in each tank will not be easy. I am thinking of leaving the hard crud stay there.

Oh, and the tanks are made from 5/32" mild steel.

We still have some more checks to do but are starting to think that the flaking rust from the bottom (outside) of the tanks, which has taken 30 years to develop, isn't all that big of a problem.
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Old 09-02-2012, 12:08 PM   #3
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Gray Hawk's prevous owner cut inspection hatches in both fuel tanks, cleaned them thoroughly and then slathered some form of black stinky goop (that's the technical name) over the entire inside of the tanks. I'm glad he did that because it looks like it was a lot of work and I also think it was a really good idea so I'm particularly glad that he did it before I had to.
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Old 06-21-2016, 08:57 PM   #4
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How are your tanks holding up?

Back in 2012 you started a thread, and I'm curious how your tanks are holding up.

Quote:
Originally Posted by Insequent View Post
I have flaking rust on the bottom of my lateral fuel tanks, but no idea how big an issue it is. As far as I can tell there are no inspection ports anywhere to help with assessment, although I suspect rust issue is mostly an 'outside to inside' issue.

I'm told that knowing the original thickness of the black iron that the tanks were made of will help assess the issue. Has anyone removed/replaced tanks, or know someone who has done this AND knows what the original steel gauge was?
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Old 06-21-2016, 09:29 PM   #5
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The Stbd lateral tank had a pinhole in the outboard aft corner, and was weeping. The port lateral tank had a lot flaking rust underneath, but was not leaking. The two aft tanks were in better condition, but did have a significant amount of rust as well.

I replaced all four tanks, with epoxy painted steel. I increased the aft tank sizes by 120 GL each. Total tankage is now 1240 US GL. Removing the tanks meant removing the engines. So I re-powered. Basically the ER was taken back to bare hull, painted, and mostly new stuff put back. A major re-fit.

Pics of rust below. First one show aft corner of tank where the leak was situated. Second pic after tank removal. The tank was resting against the hull side, trapping water. Water entry was from ER vents with vertical louvres that had no dorade protection. Water entry would mostly have been rain. It took over 30 years, but it ended up a big problem. There was a lot of flaking rust along the bottom edge of the tank.
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Old 06-21-2016, 11:12 PM   #6
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I have 1942 steel tanks totaling 2000 gallons. Never opened until a couple years ago I put in ports. Outsides had to be inspected with a remote camera and appear to be well painted. Insides had light surface rust and some deep pits in the bottom that I welded. Tanks were clean, but I had been using a quality conditioner/biocide for several years.
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Old 06-22-2016, 12:15 PM   #7
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Quote:
Originally Posted by Insequent View Post
The Stbd lateral tank had a pinhole in the outboard aft corner, and was weeping. The port lateral tank had a lot flaking rust underneath, but was not leaking. The two aft tanks were in better condition, but did have a significant amount of rust as well.

I replaced all four tanks, with epoxy painted steel. I increased the aft tank sizes by 120 GL each. Total tankage is now 1240 US GL. Removing the tanks meant removing the engines. So I re-powered. Basically the ER was taken back to bare hull, painted, and mostly new stuff put back. A major re-fit.

Pics of rust below. First one show aft corner of tank where the leak was situated. Second pic after tank removal. The tank was resting against the hull side, trapping water. Water entry was from ER vents with vertical louvres that had no dorade protection. Water entry would mostly have been rain. It took over 30 years, but it ended up a big problem. There was a lot of flaking rust along the bottom edge of the tank.
Do you have any pictures to share of this major upgrade??
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Old 06-22-2016, 06:36 PM   #8
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Quote:
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Do you have any pictures to share of this major upgrade??
Sure, here are a few.

Starting with epoxy painted new fuel tanks. Then partly installed stbd aft fuel tank.

Then space between aft and lateral fuel tanks on port side, subsequently used for water system.

Port JD engine installed.

Electrics on stbd side against rear fuel tank.

Pic from entrance to ER.

Helm shot - not obvious, but new 230 VAC 50Hz switch panel, and new/rewired 120VAC and 12 VDC panels.

Can show more pics if you are interested in anything specific.
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