Any Advice on How to Remove 130 gal Diesel Tanks

[prophecy]

I have a 1984 Formosa ketch, 48'. Our 130 gal black iron diesel tank is leaking...we have diesel in the bilge after running on a full or 3/4 full tank, so it seems to be leak from near the top. We cannot find the source of the leak, as the tank is buried between 2 bulk heads, covered with wood floor, and only has a 18" sq inspection port accessable by pulling up a removable portion of floor. (we have checked all the lines, vents, fittings that are visible, and nothing shows any leaks). the tank is also baffled. the tank is "t" shaped, going side to side, at the base of the companionway, it is about 2' wide, possibly 8' long, and 3' deep at the bottom of the "t"

so our options seem to be to
1) either cut up the floor, which means also removing glued down wood, removing the settee, removing part of the dining seating, removing part of the companionway.
2) remove the tank through a hole cut in the hull. which seems daunting, but almost easier than removing 50% of the salon.

has anyone done this on a larger sailboat?

also another concern is actually cutting up the diesel tanks to get them through the companionway....we are worried about the flammable nature of diesel with sparks from a grinder or sawzall

any advice would be appreciated

[Eumelia]

Iron is quite brittle. After you open enough of the floor, you can smash the iron tank with a sledge hammer and take it out in little bits. No need to cut up your hull or deck. I suppose you will then have to install two or more small tanks to replace it.

[JPA Cate]

As you have written, getting to the tanks will be very difficult, but doable. If you have time and willingness to tackle it yourselves. First, empty the tanks of diesel. Then, when you can get at them, what I've heard of people doing, but not done myself, is to cut the largest possible hole in the tops of the tank, where you can get at it. Then you can place new tanks in the old tank. When you put it all back together, make sure you make it so it can come apart if you want, and you'll never have to do it again. It will be a huge, time consuming job, and you may teach yourselves some new [bad] language.

Some friends of ours replaced leaking iron tanks with bladders they had custom made in Australia. It's been about 5 years now, and we've not heard there were problems with them.

Good luck with it.

Ann

[darylat8750]

I wouldn't use a grinder without some water in the tanks. Sawsall shouldn't be a problem. Black iron should cut pretty fast with a sawsall.

[HappyMdRSailor]

I go with Ann on this one... BUT... If you cannot get to all areas of where the fuel migrated to, you'll never get rid of the smell...

[Celestialsailor]

This is a common problem with the Taiwan based boats in the 70s/80s. A couple of pictures would be great to help describe where the are hidden. In the past, I have made a few out of 3/16" Aluminum. Depending on the physical dimensions of the tank and your companionway opening size, you may have to do it in 2 tanks. The other possibility is to use the existing space for storage after the tank is out and putting saddle tanks under settee's.

[GILow]

I had a similar problem with our boat and ended up removing the whole cabin sole.

But I saw this a sensible thing anyway as I did not like the fact that so much of the boat was not readily accesible in the case of an emergency such as a hull breach. It was lots of work, but in the end I am glad I did it. And by completely removing the old tanks, I was able to scrub out the inside of the hull to remove (at least one) source of diesel smells.

Finally, our boat was fitted with those bladder tanks Ann described. I am not sure how long ago, but they were fitted to the inside of the existing keel water tanks. They are now a total nightmare as they have failed, and I can not get to them without removing the engine and gearbox, which is just too much work. I have had to cap the two offending (and they really do smell pretty "offending") tanks with airtight rubber caps as the smell is diabolical.

Matt

[hpeer]

I just removed a 50 gal steel tank (3/16") from under the cockpit. Bad, but not as bad as yours.

I pumped out all the diesel I could. Flushed once with water with lots of soap. Then refilled 2/3 with water. Cut a big hunk of the top out with grinders then pumped out remaining water. Finally hacked it up until it would fit through the cockpit lockers.

Reason was suspected rust underneath I could not get to otherwise.

Now I'm left with figuring how to replace. I would really like to do integral tanks but font know if I can. Trying to figure that one out.

[Cheechako]

The idea of cutting the top out of the tank and putting new tanks in might have merit. First ask yourself how big a tank you really need? Does it make sense to have so much diesel that much of it sits for along time? i have found that. However if you are constantly on the move and rounding the globe maybe you want all that diesel.

If you order some plastic tanks that will fit thru the companionway and into the old tank shell, you could put maybe 2 or even 3 in the old shell. This allows you to fill only 1 tank until you go on a voyage and in that manner keep your fuel fresh.

Is "black iron" really like cast iron or more like steel? I always thought it was more of a semantic issue...... representing crude, minimally wrought steel? I cant believe they are welding iron into tank shapes....

Generally diesel is very hard to ignite. You can throw lighted matches in a bucket of diesel all day long and it wont ignite. I would think as long you create a fresh exchange of air all would be good... but use your own judgement. If it's not more than 1/8" thick or so you can buy a nibbler that punches out a steady stream of chunks with no sparks.

Welcome to the club BTW... I have had three tanks that were leakers.... One SS in the bilge that was 7 years old and two aluminum that were maybe 10 years old.

[Viking Sailor]

Some years ago I had to remove a 110 gal "black iron" diesel tank that was located below the cabin sole. I used a sawsall with a short blade to cut it out piece by piece. It cut very much like it was mild steel.

Step 1 was to get as much of the fuel out of the tank as possible and let it air out until almost all of the fuel was gone.

Step 2 was to cut open as much of the top of the tank as possible from the outside.

Step 3 was to lean into the tank and cut through the ends, sides, and baffles to drop sections of the top of the tank into the lower areas of the tank.

Step 4 was to cut the top pieces into small enough chunks so that they could be lifted out.

Step 5 was to break the bottom section of the tank loose and block it up so that it could be cut into chunks and removed like what was done in steps 3 and 4 above.

Best of luck to you,

Paul

[Strait Shooter]

I took two 70 gallon SS tanks out last summer. After thinking about it I cut the sole and the furniture out. It was just easier to replace all the woodwork.

I agree with the reasons to remove them. I scrubbed the diesel smell out of the bilge below the tanks, got a good look structurally at the hull interior, and got to reroute things the way I wanted to and got to redo the sole and furniture in a better layout. Gained storage spaces, added access hatches, beefed it up. It was a lot of hard work, but well worth it for me.

[HappyMdRSailor]

Originally Posted by Cheechako

The idea of cutting the top out of the tank and putting new tanks in might have merit. First ask yourself how big a tank you really need? Does it make sense to have so much diesel that much of it sits for along time? i have found that. However if you are constantly on the move and rounding the globe maybe you want all that diesel.

If you order some plastic tanks that will fit thru the companionway and into the old tank shell, you could put maybe 2 or even 3 in the old shell. This allows you to fill only 1 tank until you go on a voyage and in that manner keep your fuel fresh.

Is "black iron" really like cast iron or more like steel? I always thought it was more of a semantic issue...... representing crude, minimally wrought steel? I cant believe they are welding iron into tank shapes....

Generally diesel is very hard to ignite. You can throw lighted matches in a bucket of diesel all day long and it wont ignite. I would think as long you create a fresh exchange of air all would be good... but use your own judgement. If it's not more than 1/8" thick or so you can buy a nibbler that punches out a steady stream of chunks with no sparks.

Welcome to the club BTW... I have had three tanks that were leakers.... One SS in the bilge that was 7 years old and two aluminum that were maybe 10 years old.

I second the nibbler idea if the tank is thin enough... I have had one for years, and love it... They are loud as Eff using them though.... If you don't have an air source, they make 110v models.... Buy a good one if you go this route...

[Dulcesuenos]

Get one of those super dual blade saw tools that inventor commercial guy used to advertise cutting a car in half with.

[Pirate999]

You'll have to research it but I was told some years ago, by a company that polished tanks, that there is a spray on liner which can be used. Once done it supposedly lasts and seals any leaks. Key is that they are small leaks, not holes. Might be an option for you vs reconstruction specially if the tanks are generally in decent shape.

The other option might be to cut out the baffles and put in a large Blattner tank.

[dochip]

My Bayfield 32 has a bladder tank set into the old steel fuel tank, which had a portion of the top removed so the bladder could be installed. This was done prior to my ownership but no leaks or problems in the years since.