Fuel tank dilemma, help please

Just got bit by the weeping black iron saddle tank snake! Over Memorial weekend went down to check fluid levels and low and behold red liquid in my center bilge.....about 15 gallons worth. This happened over a week's period of time. Thank God my bilge pump didn't kick on.

Moved it to marine repair and hauled it out. I have port and starboard saddle tanks, 150 gallons each. The engines are 3208TA 375hp each. There is about 4 inches of room between outboard side of engine and tank. The mechanics are basically giving me 2 options. One is to partially disassemble motor, pick it up and move it over to center of bilge. The other option is to cut out side of boat from the outside, replace tank, re-fiberglass exterior then paint with awlgrip. Operator of services wants option two, cut out the side of boat.

I do have respect for this marina, been in business for 70 years, have done all my work for the past 2 years with not one invoice over what was quoted. They have done this procedure many, many times with excellent results. I just have a big problem cutting into a good hull along with that nagging feeling that I have compromised the hull strength.

Trying to repair tank with epoxy/welding to me is not going to happen nor do they recommend that avenue. So, if it is your boat, what direction would you might take? Thanks guys/gals

Yea not many great options on repair unless on the top, but with 15 gallons I'm guessing its at the bottom, did you just fill up?
I have seen on youtube where they actually cut the bottom out of a Grandbanks and the tank fell out through the bottom, not my idea of the way to go to me, which also includes your option 2, from a yard perspective easier I guess if a good glass guy is on staff, I would just have the engine slid over and tank removed, might even need to remove one exhaust manifold as well.

With this one, I'm in the "hoping to learn thru other replies" category. But help me understand one thing in your options. I get that if they cut through the outside they have full access to the tank and the plan is to replace it. Easy access but you have questions regarding the secondary bonding strength on the repair and a cosmetic issue, as unless painted over, I think the repair will be noticeable.
If they move the engine then they get some access, but then what? its not like you're fitting a built tank through that space?

BTW, if you're doing one tank, is it at all advisable to look at he other one closely?

What terrible timing for this to happen towards the beginning of the season!

Marlinmike said:

Yea not many great options on repair unless on the top, but with 15 gallons I'm guessing its at the bottom, did you just fill up?
I have seen on youtube where they actually cut the bottom out of a Grandbanks and the tank fell out through the bottom, not my idea of the way to go to me, which also includes your option 2, from a yard perspective easier I guess if a good glass guy is on staff, I would just have the engine slid over and tank removed, might even need to remove one exhaust manifold as well.

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Saw that vid...and from the bottom! Couldn't do it! Godd news is they have an exceptional glass guy. Repair would be much quicker doing the cut out but more expensive because of the painting of hull sides after work done. Turbos, riser and manifold need to be moved out.

I have seen a 41 Roughwater with 2 125 gallon tanks replaced with 4 60 gallon aluminum in the same space. The mild steel was cut out with a saws all. Worked out nicely with no engine or boat surgery.
Might not work for you but it is a thought.

If it was me I would move the engine. I don't see any way the hull strength would not be compromised. I am not saying that it would not have adequate strength, but I would not buy or want a boat that this has been done to. I would also do both tanks at the same time.

No Mast said:

If they move the engine then they get some access, but then what? its not like you're fitting a built tank through that space?

BTW, if you're doing one tank, is it at all advisable to look at he other one closely?

What terrible timing for this to happen towards the beginning of the season!

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Your right in that a full size tank could not be placed in that area. We're thinking a 2 part tank w/ cross over.

And that's my concern...the other tank!!!!!!

Gussets, modern epoxy, modern paint, the hull will be stronger than it was.

One would assume but I will have to ask anyway....Are you sure it is a bad tank? Could it be a fitting and/or line, return line, overflow, fuel pump issue or other? Have you determined by air pressure where in the tank it is leaking?

ragin cajun said:

And that's my concern...the other tank!!!!!!

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I would lean towards doing both tanks. I mean they're the same age and have been in the exact same conditions. At minimum I'd have it drained and inspected.

BTW if you go with the thru the hull option. I think I would involve a Naval architect. I've done it in the past. They come up with a plan of what to lay and how, then come back and attest that its been done as spec'd. With those two papers an educated buyer should understand this isn't an issue but in fact an upgrade, as now we have newer tanks and no structural issues.

Personally, I'm leaning towards moving the engine if it were me. Perhaps its an opportune time to rebuild the top end... some season. Sorry.

ulysses said:

One would assume but I will have to ask anyway....Are you sure it is a bad tank? Could it be a fitting and/or line, return line, overflow, fuel pump issue or other? Have you determined by air pressure where in the tank it is leaking?

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No such luck! Leak is from behind tank mid way up.

Pressure testing would be (IMHO) the first thing to do. Normally tanks are pressurized to around 3 psi for leak down testing. At that pressure it should be easy to find the leak. You would want to start out by removing as much fuel as you possible. Pressure should be brought up slowly to insure a catastrophic failure does not occur. You could just a easily find the leak at a lower pressure depending on its severity. I also like others have said would be suspect of the other tank as well. Test both.

Strange that the leak would be halfway up. Normally one would think of failure in the bottom due to corrosion.

Next question will be what do you replace it with if found bad. Will you be able to replace with equivalent tankage in a different material? I know the though of replacing both tanks might make you cringe (sure would make me) but this is the time to find out if the other is bad as it won't get any cheaper to do in the future.

The first thing I'd investigate is the reason the tank failed.

Then armed w that knowledge one could predict if the other tank was likely to fail not too far from now. Having the second tank fail soon after replacing the one in question could be a bad day at black rock.

If the failed tank failed from age I'd imediately scuttle the notion of cutting the side of the boat out. Lifting out the engine opens doors to a number of options you may not want to pass up. We had one tank fail. We pulled the engine and replaced them both. Furthermore we repowered as well. Sold the 35 year old engine and replaced w new. Dosn't look to be an advantage for you but replacing the other tank could be a very good move .... especially considering resale value.

I'd need to know why that tank failed.

Capt. Jon said:

Pressure testing would be (IMHO) the first thing to do. Normally tanks are pressurized to around 3 psi for leak down testing. At that pressure it should be easy to find the leak. You would want to start out by removing as much fuel as you possible. Pressure should be brought up slowly to insure a catastrophic failure does not occur. You could just a easily find the leak at a lower pressure depending on its severity. I also like others have said would be suspect of the other tank as well. Test both.

Strange that the leak would be halfway up. Normally one would think of failure in the bottom due to corrosion.

Next question will be what do you replace it with if found bad. Will you be able to replace with equivalent tankage in a different material? I know the though of replacing both tanks might make you cringe (sure would make me) but this is the time to find out if the other is bad as it won't get any cheaper to do in the future.

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Aluminum custom tanks and you're right I'll take a close look on port tank.

manyboats said:

The first thing I'd investigate is the reason the tank failed.

Then armed w that knowledge one could predict if the other tank was likely to fail not too far from now. Having the second tank fail soon after replacing the one in question could be a bad day at black rock.

If the failed tank failed from age I'd imediately scuttle the notion of cutting the side of the boat out. Lifting out the engine opens doors to a number of options you may not want to pass up. We had one tank fail. We pulled the engine and replaced them both. Furthermore we repowered as well. Sold the 35 year old engine and replaced w new. Dosn't look to be an advantage for you but replacing the other tank could be a very good move .... especially considering resale value.

I'd need to know why that tank failed.

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That will be my first question on Monday when talking to marina. Tanks are 28 years old.

Dread the day when when our black iron number shows up. I went all over the boat last week trying to look at the tanks and could see little other than the access panels. I see no rust or corrosion and they look very good. I suspect if we took the boat down to FL, the tanks would break out like they had leprosy.

Since our hull already needs awlgrip, I would opt to have the hull cut.

I suggest you find a good marine surveyor to look at the boat, look at both tanks, look at moving the engine(s). At the boat yard where I work the yard management really likes a qualified outside surveyor to advise the owner and then there is never a question of the yard suggesting too much work at a higher cost. Plus the documentation from the surveyor will help when selling the boat sometime in the future, and might help in an increase in value, although the increase will be less than your expense.
Here is a picture of an aluminum yacht getting new engines but aluminum is easier to cut and weld back at full strength.

28 year old tanks makes me assume 28 year old engines...

Cutting the side of the boat gives me no pause whatsoever. Modern materials and methods coupled with good craftsmanship should make the repair stronger than the hull is currently.

The idea of pulling down the top end of those engines and turbo's is tempting. It may be more expense but IMO it is far more value to you going this way. Let's face it, your hull is as strong as it needs to be and assume it's cosmetically adequate. Top end rebuilds have never hurt an engine that I'm aware of and can add both real value and current utility to your boat.

You don't tell us a couple of things, how many hours on the engines? Can they benefit from some top end work. What are your long term plans with the boat? Are you keeping her for another 5-10 years or selling next year for the new one. If you are, cut both sides repaint,call it a day. If not then you need to think engines as part of this. If you don't and they are getting to the point where they will need attention in the near future odds are you'll be raising a question during the summer season about engine repair.

CPseudonym said:

28 year old tanks makes me assume 28 year old engines...

Top end rebuilds have never hurt an engine that I'm aware of and can add both real value and current utility to your boat.

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Ummmm....good point!

mbevins said:

You don't tell us a couple of things, how many hours on the engines? Can they benefit from some top end work. What are your long term plans with the boat? Are you keeping her for another 5-10 years or selling next year for the new one. If you are, cut both sides repaint,call it a day. If not then you need to think engines as part of this. If you don't and they are getting to the point where they will need attention in the near future odds are you'll be raising a question during the summer season about engine repair.

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I have 2100 hrs total. In frame rebuild done at 1,150 hrs on both. Valves adjusted last month. I burn very little oil w/ no smoke. I bought this boat from an individual who needed to get out at any price. Knowing that this boat had been neglected for over a year needing cosmetic as well as mechanical work, I allowed for a 100% refurbish allowance to bring the boat up to good cruising specs. I've gone through 1/2 that allowance in a year and 4 months with auto-pilot and repair of trim tabs left on my to-do sheet. So I do still have boat dollars to address the tank issue. I hope to keep the boat for at least the next 5 years. The admiral likes this boat!

Based on what you are telling us, I'd lean towards cutting out the bottom and replacing both tanks. Taking apart well running engines for no reason can have also sorts of unintended consequences. Many of them potentially bad.

Capt.Bill11 said:

Based on what you are telling us, I'd lean towards cutting out the bottom and replacing both tanks. Taking apart well running engines for no reason can have also sorts of unintended consequences. Many of them potentially bad.

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Thanks Capt, great point. I hate the idea of disassembling good running engines. They would not be going through the bottom but rather the sides. This option also gives me something to show for all that money I'm spending with a new paint job! If I go this route I'm gonna bite the bullet and do both side tanks.

I agree with Bill. Also you'll have a nice purty paint job!

A friend had leaking tanks he and a buddy cut them apart inside the boat using a plasma cutting torch, carefully, watching for fire etc. Then he replaced each tank, about 150 gal, with two smaller tanks. It worked out well I know another guy who cut his up with a Sawzall doing a similar replacement. You lose a bit of fuel capacity but unless you are going to be doing long range cruising does that matter much?
Good luck!

With only 1000 hrs since your inframe, I see no reason to take apart those engines, Yes, inspecting and replacing parts if necessary is a good thing, but you haven't even broken them in, much less worn anything out. I'd lean towards taking them out the sides were it me. And a new paint job be ALWAYS good!

Dock neighbour of mine, after a lot of agonizing, finally followed the advice of the local well-regarded shipwright and cut out the side of his hull to remove/replace fuel tank. The grp hull had molded lapstrake planking effect, so he was understandably worried about not just structural integrity of the hull but the difficulty of matching the repair with the rest of the hull. In the end, job went very well and even with the boat up on the hard it is impossible to see the repair area...let alone when she's in the water. I think getting input from a naval architect would be a good idea, as suggested.


I haven't seen the youtube link to the vid showing the bottom of the hull, rather than the side, being cut out to drop the offending tank: I can imagine that would be a better/cheaper option in many respects. Anybody have the link to that?

Hi R C.

I have nothing to offer you except best wishes on your choice and after all the advice it is your decision.

Hi Aquabelle.

I saw that fuel tank replaced on youtube and the blokes doing the one I saw looked very second hand in the experience department, you should find it on goggle by searching " fuel tank replacement boat ".

Regards to Ragin Cajun.

David.

Thanks...I did just find one showing a Grand Banks' tank being dropped out the bottom of the hull; perhaps that's it. Looked a good way to get it out to me...fast and no need to fully repaint hull sides. I wonder how the new tank would be inserted and the bottom repaired? Tank goes up and in...then moved out of the way to other side of engine room I guess, then with hull repaired tank is moved into place and connected up/fixed down?

One little trick we often used when welding or cutting on fuel tanks and/or fuel barges-especially if they had fuel in them was to drop in some dry ice prior to welding. This displaced the O2 in the tank with CO2, we hardly ever blew one up.

dk

I am familiar with the problem, and ended up doing all four tanks even though the two rear ones still had some life left in them. My tanks were black steel. Aluminum tanks can have major issues with poultice corrosion - correct fitting of them is critically important. So new tanks were steel with multiple coats of good epoxy paint.

In my case the yard felt that although cutting the side out might be a cheaper method of tank replacement, for optimum FRP repairs you need to do both sides of the repair area. Once the new tank is in place you are unlikely to have access to the hull from the inside.

So I removed the engines to get access to the side tanks. They had only done 1900 hours, started at first crank, did not smoke, reached WOT etc. But they were 30 years old. So the yard costed hose replacement and other R&M on the engines for me. It came to a scary number, and at the end of it I still had old engines for which parts were hard to get and/or expensive. So I ended up spending even more money for a repower with new John Deere's. New tanks in the sides was the initial driver, but not the main cost in the end.

We also looked closely at my rear tanks. One was clearly on its way out and the other showed some corrosion but would last for quite a while. Since I had decided the boat was a keeper for a long time, the smart thing to do was replace both rear tanks whilst there was good ER access.

Then, with the ER all but empty it was prudent to replace 30 yo hydronic heater hoses (nominal 10 year life) and hot/cold water lines. Etc. While we have access...... There goes a few more boat bucks....

The side tanks developed leaks because of rain water entry through the ER vents. So the vents were retrofitted with dorade-type drains to prevent re-occurrence. The tank leaks were on welded seams at corners, but large amounts of rusted steel was flaking off the sides of tanks where they were in contact with the hull, and on the bottom.

I will never recoup the refit expenditure. My advice to the OP is to really think hard about whether it is the right boat for you for 15+ years. If so, remove the engines and put in new tanks and do other "whilst we have good access' upgrades or replacements. Be aware it will be expensive.

If you have any doubt about wanting a different size boat in, say, 5 years then look at other options. The cut the hull repair method may be a good option for you as your yard has been there, done that and has a track record of coming in on repair quotes. But I would also investigate the sawzall cut-up in-situ of the tanks, and replace with multiple smaller tanks. If you do that you can just do the one that is leaking now, and defer the other side for a bit. The other one might have 5 years or more life in it anyway.