Replacing Fuel Tanks... a New Idea?

[minaret]

Originally Posted by shorebird

Minaret may well be the master craftsman in building glass tanks, which, in and of itself, is quite a technical challenge, and the results may be very good. Most of us, however, are not skilled fiberglass fabricators, and although a novice may be able to glass over an existing tank to his or her own satisfaction, I repeat, if I were boat shopping and came across a previously leaking tank glassed over by its owner, I would run, not walk away. I think bladders have some real potential when used in containment and for smaller, non-baffled tanks many sailboats use. It could be feasable to consider my idea of a bolt/gasket tank as containment for a bladder tank, rather than the tank itself. It would require much less precision and expense, although now you would have the added cost of the bladder tank. Now, if I were boat shopping, and came across a stainless steel "tank" professionally made and lined with a properly fitted bladder, I think I would consider that a "proper" permanent tank, as would (hopefully) surveyors and insurance companies. A small opening with a plug on the bottom of the containment would serve as an indicator of internal tank failure. I also like galvanized steel as a material. In theory, 2 bladders in one containment could also address the problem of larger tanks providing some means of linking them is used. Now lets carry this just a little further. Maybe the new tank of the future is to use a containment compartment, lined with a bladder(s). If and when the bladder fails, the solution is to replace the bladder, hopefully by removing the old one, and installing the new one though an opening previously considered hopeless with a rigid tank. I really appreciate all the comments.

Bladders in tanks are notorious for failure due to chafe.


There is already a system on the market which uses a double walled bladder, with the space in between filled with a high strength heat curing resin. You insert the bladder into the space in question (could be a tank), insert a special balloon contraption into the bladder and inflate it. This presses the bladder into a shape by positive pressure. The balloon has a heat lamp built into it which you then turn in and leave running for a couple of days. This cures the resin, forming a new tank wall. I've discussed it here before, but don't remember the product name now. Better than a soft bladder, but not as good as glass.

[minaret]

Originally Posted by zeehag

minaret i so love you. thankyou.
i have been trying to figure this one and you slam dunked it.
this method or risking burning down my boat have been the only two solutions so far that include decent capacity.
i didnt think much of the plumbing in more than one tank...that won silver medal.
.i like your idea better.
thankyou

Consider this sort of thing as well.



Tank Sealer - Gas Tank Liner - Diesel Tank Sealer - Fiberglass Tank Sealer

[shorebird]

As I mentioned, there certainly are some alternatives to a complete tank replacement, including liners, bladders, glassing, all have been used, and all have had mixed success.
Some are recognized by regulatory agencies and insurers and some are not. In particular, Minaret's glassing inside the tank would be difficult or impossible in my particular boat due to access restrictions, but under some circumstances, if PROFESSIONALLY done, could be considered a proper, permanent fix, but if done by someone with the nickname "duct-tape" i'd still pass. The same goes for fabbing glass and wood tanks mentioned on other threads, completely acceptable to some, and advocated by many, I personally would not buy or try to insure a vessel with home made tanks of any kind. I also would not accept a bolt-together contraption such as my original idea, but I still think the idea has merit as one of several alternatives to the leaking tank problem, and given some testing, could be a way to completely replace a tank with a new steel one without major renos to the vessel. Degradation of the gasket over time is just one concern this bolt together idea needs to address. If I were to fab one up for my own boat, I would include containment until the idea is proven over time. Again, really appreciate all the comments, and feel free to add more.

[HappyMdRSailor]

For the OP:

Your idea definitely has merit... I see "ancient"oil tanks all the time that remind me of what boilers on the Bismark must have looked like.... Bolted together patchwork of steel plates.... But of course we are talking non "marine" environments here... AND.... so heavy as to be completely impractical on a boat... Alloy design could have merit... I just don't see a huge market for it....

Minaret has the right idea.... In fact... I'm just about to suggest it for a "new construction" tank for somebody... I wouldn't do anything but glass in an old tank if it were "unremovable"

[minaret]

Originally Posted by HappyMdRSailor

For the OP:

Your idea definitely has merit... I see "ancient"oil tanks all the time that remind me of what boilers on the Bismark must have looked like.... Bolted together patchwork of steel plates.... But of course we are talking non "marine" environments here... AND.... so heavy as to be completely impractical on a boat... Alloy design could have merit... I just don't see a huge market for it....

Minaret has the right idea.... In fact... I'm just about to suggest it for a "new construction" tank for somebody... I wouldn't do anything but glass in an old tank if it were "unremovable"

Just stay away from integral glass tanks, ie tanks where the hull forms one wall. Every glass tank horror story I've ever seen was integral. And not sealed properly.

[HappyMdRSailor]

Originally Posted by minaret

Just stay away from integral glass tanks, ie tanks where the hull forms one wall. Every glass tank horror story I've ever seen was integral. And not sealed properly.

Definitely wasn't going to do this... BUT.... It's advice like this that saves the "unmentioned disaster" !!! THANKS MAN! (I'll link the thread)

I have had this thought about 20x.... I sure wish I had a "Shangri-La" villa complete with staff and motorpool/boaterpool so I could entice Minaret to hang out for a few weeks here and there.... when professional hands on consulting would be nice...

[Flem.S.Coyle]

Originally Posted by HappyMdRSailor

Minaret has the right idea.... In fact... I'm just about to suggest it for a "new construction" tank for somebody... I wouldn't do anything but glass in an old tank if it were "unremovable"

I stumbled on this thread and don't want to "drift" it, but yeah. Now I see why my PO put the plastic tank in the sole next to the quarter-berth. There are things that might actually need fixin before I go chopping out the old tank, but I see the beauty in what Minaret's doing.

Filed for later reference.

[tommyboy-afloat]

Hi minaret and all, specifically to minaret since his yacht is the same as mine.
In short I have to replace the fuel tanks, starboard one leaking, port still ok, will stagger the job for various reasons.

I read your refit, am at about page 40 something with square eyes.

I saw your waste tank rebuild and being experienced you made it look easy and great.

What about your fuel tanks? Given that the starboard tank (my leaking one) is under the radar and pilothouse door (mine is the hybrid change from the 52 to the 521, 521'S DIDN'T HAVE THE SIDE DOOR) and the only access is from the engine room behind the genset, how did you do that tank?

I cannot get into the top at all and am planning to cut into the side of it ( it is 1.7 m long, .7 m wide and about 1.1 m high) and open up enough room to either put in a bladder tank (you mentioned one that has 2 membranes and resin that can be formed and fitted to harden in a cavity) or plastic tanks.

Ok does anyone know of this 2 skinned membrane tank? and in france, who knows of a tank manufacturer that I could get from over here.

Obviousluy I will lose some volume, I can live with that more than the stench of diesel. I found the leak at the v in the sump, and could see bubbly paint along the weld on that side of the tank. Squeezed hand into a hole and did magic hand manipulations to get the shot. Please see.

Anyway any advice would be great as I have to do this in a very short time and need to get the hell out of the eu before my visa expires (2.5 months and counting down ) The shengen visa stinks for cruisers in the med and other parts of the eu.

Thanks in advance.

[minaret]

Originally Posted by tommyboy-afloat

Hi minaret and all, specifically to minaret since his yacht is the same as mine.
In short I have to replace the fuel tanks, starboard one leaking, port still ok, will stagger the job for various reasons.

I read your refit, am at about page 40 something with square eyes.

I saw your waste tank rebuild and being experienced you made it look easy and great.

What about your fuel tanks? Given that the starboard tank (my leaking one) is under the radar and pilothouse door (mine is the hybrid change from the 52 to the 521, 521'S DIDN'T HAVE THE SIDE DOOR) and the only access is from the engine room behind the genset, how did you do that tank?

I cannot get into the top at all and am planning to cut into the side of it ( it is 1.7 m long, .7 m wide and about 1.1 m high) and open up enough room to either put in a bladder tank (you mentioned one that has 2 membranes and resin that can be formed and fitted to harden in a cavity) or plastic tanks.

Ok does anyone know of this 2 skinned membrane tank? and in france, who knows of a tank manufacturer that I could get from over here.

Obviousluy I will lose some volume, I can live with that more than the stench of diesel. I found the leak at the v in the sump, and could see bubbly paint along the weld on that side of the tank. Squeezed hand into a hole and did magic hand manipulations to get the shot. Please see.

Anyway any advice would be great as I have to do this in a very short time and need to get the hell out of the eu before my visa expires (2.5 months and counting down ) The shengen visa stinks for cruisers in the med and other parts of the eu.

Thanks in advance.

That's a tough one. I pressure tested and inspected my fuel tanks, and they are good to go. Not sure they'd be good candidates for a glass job, due to the shape of the tank. But, these tanks were well built, with a proper sump. Any corrosion should be in the sump only, in theory. Particularly if they have been well taken care of. It sounds like this is exactly what you are describing. So it may not be all that huge a problem. You need to access the inspection plate on top of the tank, pump the tank out dry, and get it really clean for inspection. Then you'll know where you stand. If you can get to the bottom of the tank and cut off the sump to weld on a new one, that would be a good fix. But I doubt it's possible. Consider coating the interior of the tank, there are a number of products designed for that. I think you'd be fine with that, as we are almost certainly not talking about a tank which is completely shot. Nauticat used serious steel for everything, I couldn't get them to tell me which alloy they used for fuel tankage but it's something high end. They told me they should be good for the life of the boat, which I'm sure is BS, but my point is it probably isn't 316 and may require careful sourcing of material. Every screw and bolt on my boat was A4. If you have to remove this tank, it will be quite a job requiring more time than you have available. The standard method involves removing the generator, the pilothouse floor, and the pilothouse roof. All of which is designed to go off and on fairly easily, but still it's a huge job. I was very pleased to dodge that bullet this time. My PO was a ships pilot, was very serious about clean fuel. Never seen a single drop of water in my separators, not sure how it's even possible with that much tankage! Do you regularly use your bottom drains?

Post a pic or two if you can, I'd be glad to try to help however possible. Sounds to me like you need some sort of temporary band aid to get you some time to research this and find the right person/place/time for the job. At least it's not the port tank, that sucker is even harder to get to!

[minaret]

Can you remove the longitudinal partition between the generator and the fuel tank (guessing you already have) to access the whole inboard side of the tank? Then remove the pilot house floor for easier access, and find a very good welder. Have him cut a big access panel in the inboard side of the tank, cut out the sump from inside the tank, build a new one, weld it in, and then weld back up the access panel you cut. Could work, if you can find a welder who is willing and can do the job with access from only one side.

[tommyboy-afloat]

Originally Posted by minaret

Can you remove the longitudinal partition between the generator and the fuel tank (guessing you already have) to access the whole inboard side of the tank? Then remove the pilot house floor for easier access, and find a very good welder. Have him cut a big access panel in the inboard side of the tank, cut out the sump from inside the tank, build a new one, weld it in, and then weld back up the access panel you cut. Could work, if you can find a welder who is willing and can do the job with access from only one side.

Thanks for your reply. I have not removed the wall in the engine room abutting the tank is that is what you mean. I am still removing 'stuff' and trying to get the fuel out of the tank.
I spoke to the local SS welder and he cannot do the job. I will probably get a plastic or two to insert into the old tank slot. Id love to get a fabricator but in the time frame I have to get out of here it may not be possible. I have to also remove the fiberglass cased timber that levels the tank in that bulkhead as it is impregnated with diesel and I need to remove or else the family will not live on her.

Best scenario is a tank made up, middle is take one end off the tank and shorten it if the rest of the tank is in good condition and worst case is insert plastics into the void. I will re build the timber level regardless in some way shape or form so as the tank can sit level, (when the boat is level).
How would you 'happily' cut into a diesel tank? Flush it first with soap and water? blow fresh air into it? or suck it oiut? A friend used a grinder and had no problems however everyone here is scared of an explosion. I have put matches out in diesel (when I was a boy).

I tried to send photos, ill try again.

Tanks for your previous reply. Excuse the pun.

[tommyboy-afloat]

The owner/PO has agreed to remove the replacement of the tank replacement off the cost of the yacht he is very apologetic and really wants it to work for us. He even wants to sail with us , he is 80and bought it 2 years ago to sail with his friends however it didn't work out as planned for him. I am happy to have a relationship with him and as mentioned he is genuine and wants to help. It is a lovely yacht, a bit tired in areas but generally in vgc. Some rooms look like they have never had anyone in them.
I am in it for the long haul now, he has my deposit and will get the rest once all is fixed and it is wet tested. I had it surveyed however it took me 3 days to source the diesel leak and it has been on the dry now for 7 months since survey. The bilges have not been operating and the diesel has had time to accumulate.

I was a bit overwhelmed at first however I am pretty handy and see the old tank out in bits if need be in a week from when I get all the fuel out into drums (have to source the drums). I'm in france and as you could imagine from just arriving I need to get my feet on the ground to find the right service providers.

photo of top of tank and also the first 3 liters of fuel i pumped out of the sump of the starboard tank. The port tank was clean with no contaminants straight away..

I really need a permanent fix for now.
Speak soon

[BriRich]

I just replaced the fuel tanks on Amihan. My friend that has done the refit is a shipwright and does awesome f-glass work. I suggested f-glass and making molds. He didn't like the idea even though it would mean good work for him. The cost of making the molds is what turned him off. Unless you are a f-glass guru and can do it yourself the cost may be high.

Instead we took out the 30 year old steel tanks and replaced them exactly with new steel tanks with a good coat of red primer stuff on them.

[bornyesterday]

Couple of things occurred to me reading your posts...

Risk of explosion is very real. Heat from cutting & welding vaporises fuel residues into explosive mixture with air. Steaming for a long time used to be preferred - a day or two was usual IIRC.

Until you've paid in full you don't own anything. Usually.

Old people sometimes die unexpectedly, heirs aren't always so nice.

Economies can go up as well as down - values/prices then tend to rise and other buyers appear.

I may well have misunderstood your posts of course...

[Terra Nova]

Because most/many builders first install tanks, then build the boat around them, their repair/removal/replacement is problematic. There have been many work-around's tried simply because few had the skill to surgically remove and replace that section of the yacht's interior which stood in the way. Other than complete removal and replacement with a new, improved tank, each individual tank installation requires its own repair solution.

Sometimes it may be easier and faster to access a tank repair, directly, by cutting an access hole in the hull plating. But generally a professional can remove the interior in such a way as to allow its later reassembly with relatively little to repair, cosmetically. An oscillating multi-tool can make a very thin cut and is one of the handiest tools for this preparatory work. But one needs to begin with a well conceived plan.

The size of the entryway generally limits the size of the largest new replacement tank which can be brought aboard. Though a new or existing hatch opening can facilitate this.

As for using the old, leaky tank as a "mold", that might suit certain scenarios. It sounds easy until you get to the part of installing the new tank top so it seals to the tank sides, and stays that way. Also the tank penetrations. And it is a huge, dirty job.

Regarding integral tanks, with proper design and technique, they can sometimes be the best solution. It is the design of the attachment of the tank top that will create difficulties.