Fuel tank leak

[Bouba]

That looks like a VERY difficult job if the tank needs to come out. Engine out isn't trivial and it looks as if the tank sits on or close to the hull behind a raised GRP frame. There might be room to lift it over the frame and slide it aft under the engine access hatch. However, it doesn't look like there would be any room to turn it for removal.

Either a huge hole is cut in my kitchen floor or it’s engine out

 

[Freebee]

On the top[ of the tank I can see one fuel hose with a closed ball valve . and next to it another hose with no valve is that a fuel return or feed to something else ??? If the hose were holed and the pipe in the tank was down into the fuel it just might syphon over????? its a lot of ifs!!

 

[Mistroma]

Either a huge hole is cut in my kitchen floor or it’s engine out

Yes, depressing. I sometimes wonder what boat builders are smoking when designing boats. Or it's all meant to be a cruel joke and keeps them amused.

I probably added a few other thoughts while you were replying to the post quoted, might be worth reading again just on the off chance there's something useful.

 

[Bouba]

On the top[ of the tank I can see one fuel hose with a closed ball valve . and next to it another hose with no valve is that a fuel return or feed to something else ??? If the hose were holed and the pipe in the tank was down into the fuel it just might syphon over????? its a lot of ifs!!

Yes there is feed and return lines for the generator and another two for the engine. All are dry to the touch

 

[Portofino]

Have you opened up the geny box to check its fuel pipes are secure ?
Feed , filter , return .A fuel pump as well .Any one could have come loose , perforated or need a clamp nipping up .

Same with the engine pre filter ( racor ? ) and the geny ?

 

[Mr Googler]

I think a bladder is defo the way to go. Here’s a uk company

Marine | Below & Above Deck Boat Fuel Tanks | Aero Tec Laboratories

No doubt need to cut a big hole in the top and shuffle connections about but that’s easy and your access to the tank top is excellent!

I wouldn’t lose any sleep….can’t see it being more than a couple of days work once all the fuel is sucked out.

At least it’s not full! ?

I would pressure test first though if possible…not to find the leak necessarily…..but to confirm it’s not holding pressure and it’s defo the tank.

 

[Fr J Hackett]

Either a huge hole is cut in my kitchen floor or it’s engine out

That is probably going to be the way to go if it is the tank, it should be an easy job to repair the floor and put a new finish on it Amtico or something similar.

 

[Bouba]

Have you opened up the geny box to check its fuel pipes are secure ?
Feed , filter , return .A fuel pump as well .Any one could have come loose , perforated or need a clamp nipping up .

Same with the engine pre filter ( racor ? ) and the geny ?

I was going to do a double check on the genny but I pushed my back as far as it could go today. Tomorrow it’s a trip to Beneteau, the wife is laying down the law

 

[Mr Googler]

6 years isn’t exactly old for a fuel tank!

I think @Portofino is onto something with stresses during lift. Looks like it has tabs welded at the base to bolt it down?

 

[benjenbav]

I was going to do a double check on the genny but I pushed my back as far as it could go today. Tomorrow it’s a trip to Beneteau, the wife is laying down the law

If the fuel tank does have to be replaced, perhaps it could be cut up in situ for ease of removal and replaced with two or three smaller tanks to avoid cutting the floor above or taking the engine out.

 

[Bouba]

If the fuel tank does have to be replaced, perhaps it could be cut up in situ for ease of removal and replaced with two or three smaller tanks to avoid cutting the floor above or taking the engine out.

I was wondering that

 

[julians]

Full of good news today aren’t we?‍
Just came from the boat (will post photos later). Another one litre after two days. All evidence is pointing to the tank. A major job if there ever was. Tomorrow we’ll go talk to the Beneteau shop and get their opinion (I’m actually very nervous, it could cost anything...).
Impossible to see the bottom or sides or the other face of the tank. It’s right up against a bulkhead that’s covered in sound deadening foam. To get access it in order to drill from the other side will require removing loads of trim and having nerves of steel. And for what? Is it simpler to just take the tank out without actually finding the source ? And what’s the technique, engine out? And the logistics of getting the boat to their yard. And the cost. And do we upgrade the tank?
Lots to keep we awake tonight

Good excuse for a new boat?

 

[vas]

If the fuel tank does have to be replaced, perhaps it could be cut up in situ for ease of removal and replaced with two or three smaller tanks to avoid cutting the floor above or taking the engine out.

my thoughts exactly!
tank is ali, looks like nicely made, will cut in 3-4-5pieces easily to remove it from there.
then do what Versilcraft did on mine 45yrs ago, multiple tanks with top and bottom connectors (top for vent and fill, bottom for balancing). I have four across the width of the boat, removing a few pipes I'm pretty sure I'll be able to remove them one by one without too much trouble.
Built 2 custom ss tanks and fit them in the place of the two. Even if you loose 5% of the total you'll be fine.

 

[julians]

In actual fact the bottom of the tank is vee shaped. And the center is the lowest point. We cleaned before and it didn’t look like it’s had fuel on it but I have put some white powder and will check it in two days time.
The whole fuel tank should be on a liner, in which case that is the only place it could flow through. But here’s the problem....it would fill the bilge under the engine first, and that can hold at least a litre or more. But it’s dry (it used to fill now it doesn’t).
There is a possibility that the fiberglass, gel coated liner has a drain hole in it or there’s a gap behind it and the fuel is going straight to the hull.
No matter how I look at it logically, there is always a mystery. And until I can see under and behind the tank, I can’t be certain

I agree that it doesn't look like the tank is leaking from those photos, you'd expect to see traces of it on the fibreglass running from under the tank, unless the fibreglass the tank sits on is a liner and the fuel is getting under it, running. Towards the stern and then coming up through some hole to reappear under the engines.

That is mysterious.......

Are you sure it's not from a fuel line at the engine end? Could it be syphoning from the tank?

 

[sharpness]

Fitting a bladder inside the existing tank is an option mentioned previously on other posts with people suffering leaking fuel tanks.
For this to work would the baffles in the leaking tank have to be removed ? Not an easy task i imagine.

 

[BruceK]

Good excuse for a new boat?

Or make a living off this one as a diesel barge? Comes with free advertising!



Ag shame Bouba. My heart actually goes out to you. Terrible blow by any account. Hope you sort easily and it doesnt break the bank. I'm hoping it's a rubber hose line with a bit of vibration wear.

 

[Bouba]

I agree that it doesn't look like the tank is leaking from those photos, you'd expect to see traces of it on the fibreglass running from under the tank, unless the fibreglass the tank sits on is a liner and the fuel is getting under it, running. Towards the stern and then coming up through some hole to reappear under the engines.

That is mysterious.......

Are you sure it's not from a fuel line at the engine end? Could it be syphoning from the tank?

I thought about siphoning, but the feed lines are now shut off at the stopcock, and surely the return lines just dump their fuel at the top of the tank? And it’s only a 1/4 full
The tank is sitting on the liner. It’s possible that under the tank there’s a drain hole in the liner or a gap between the liner and the bulkhead that the tank rests against.

 

[Bouba]

Or make a living off this one as a diesel barge? Comes with free advertising!



Ag shame Bouba. My heart actually goes out to you. Terrible blow by any account. Hope you sort easily and it doesnt break the bank. I'm hoping it's a rubber hose line with a bit of vibration wear.

It would be the first boat ever if it didn’t break the bank.

 

[dj43]

first you need to find the leak, that looks a very easy tank to test, drain , disconnect outlets plug and air test, if ok do each supply line and return individually,

 

[MapisM]

tank is ali, looks like nicely made

I agree that it looks well built in the pics, but are you saying it's aluminium from them, or because Bouba said so?
I've seen s/steel tanks (non/polished, obviously) whick looked very similar.
Which brings me to the next question to Bouba, what made you say it's aluminium?