Fuel tank steel thickness

Insequent · Jul 9, 2012

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?

Insequent · Sep 1, 2012

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.

bobofthenorth · Sep 2, 2012

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.

KevinCT · Jun 21, 2016

How are your tanks holding up?

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

Insequent said:
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?

Insequent · Jun 21, 2016

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.

Lepke · Jun 21, 2016

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.

Max Simmons · Jun 22, 2016

Insequent said:
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??

Insequent · Jun 22, 2016

Max Simmons said:
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.

bshillam · Aug 30, 2019

Now that's a clean ER. If you ever decide to sell please offer this one to the group first. I love how professional the wiring is, the access in the ER is great. Wonderful job with the refit! I realize the post is years old. How are you enjoying the new engines? Would you do it again or choose another brand/power/etc?

Pete Meisinger · Aug 30, 2019

Care to share the cost ? My P.O. had both steel tanks removed, cut the bottoms of them and reinstalled with new bottoms. Of course the engine had to come out. This was over 10 years ago and I believe the cost then was about $8,000.00

New tanks are like a new engine. A great selling point but don't really add anything to the selling price.

It sure is beautiful work!!

pete

Comodave · Aug 30, 2019

I am planning on replacing one of my tanks over the winter. My tank is 210 gallons and I have a quote for 1/4” 5052 aluminum around $2200 plus shipping and any optional cleanouts.

Insequent · Aug 30, 2019

bshillam said:
Now that's a clean ER. If you ever decide to sell please offer this one to the group first. I love how professional the wiring is, the access in the ER is great. Wonderful job with the refit! I realize the post is years old. How are you enjoying the new engines? Would you do it again or choose another brand/power/etc?

The new John Deere's are great. I thoroughly recommend them! They now have 1800 hours.

Would I do it again? I enjoyed the process, basically all new systems which I am very familiar with having been onsite for most of the work. For the right boat, yes,I probably would do it again.

No plans to sell, it was always going to be a boat I kept for a long time. You cannot justify the cost otherwise.

Insequent · Aug 30, 2019

Pete Meisinger said:
Care to share the cost ? My P.O. had both steel tanks removed, cut the bottoms of them and reinstalled with new bottoms. Of course the engine had to come out. This was over 10 years ago and I believe the cost then was about $8,000.00

New tanks are like a new engine. A great selling point but don't really add anything to the selling price.

It sure is beautiful work!!

pete

I had a lot of work done, and don't know the cost of individual items as the labor in particular was not broken down in that level of detail. Overall cost is something I've never talked about. It was a stupid amount, no make that really stupid amount to spend! But I like the result! Materials for the refit came to US$350k in 2012-13. Did I mention I did replace just about all systems? I did increase the value quite a bit, but nowhere near what I spent.

For tanks, if you need to remove and replace engines for access then the cost increases a lot. In part because its the ideal time to replace a bunch of other stuff that is difficult to access normally so project scope expands quickly.

Comodave · Aug 30, 2019

Yes, I agree with the idea that with the engine out it is the time to replace hard to access equipment. At a minimum I am going to replace the aft head because I will be able to get to the area and run new holding tank hoses and water hose to the head. I am also going to replace all the hoses on the port side. Maybe the water heater. So the project does snowball...

Fuel tank steel thickness

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