Fuel tank leak

[KompetentKrew]

I haven't read the whole thread, so apologies to @Bouba if you've already identified the leak, but I have recently experienced a most unexpected fuel leak on my boat - it came from the top of the tank. I have been on the hard for some time, and appear to be at a slight angle with the bows raised very slightly higher than the stern - thus a small amount of fuel was escaping the inspection hatch in the top of the tank. I hadn't noticed the angle all this time, despite living onboard, but several litres of fuel ended up in the bilge, and I had to pump litres more into the other tank before the leak stopped.

 

[Clancy Moped]

View attachment 126437

This is the corroded weld inside the aluminium fuel tank at 6 years old caused by water and fuel bug, the tanks were replaced with stainless to the same pattern.

That is shit welding work, what makes is that tank?

 

[Bouba]

I haven't read the whole thread, so apologies to @Bouba if you've already identified the leak, but I have recently experienced a most unexpected fuel leak on my boat - it came from the top of the tank. I have been on the hard for some time, and appear to be at a slight angle with the bows raised very slightly higher than the stern - thus a small amount of fuel was escaping the inspection hatch in the top of the lid. I hadn't noticed the angle all this time, despite living onboard, but several litres of fuel ended up in the bilge, and I had to pump litres more into the other tank before the leak stopped.

I have had this leak while the boat was in the water, while it was being used and now on the hard
It started off small and manageable, indeed I thought originally it was a loose fuel inlet/outlet port on the engine. It was weeping. So I cinched it up and thought my problem was over. But slowly it came back and has increased in volume (possibly after a fuel up). But the tank only has a quarter fill.
My current thoughts are......
The leak came from the tank. And the tank sits on the liner, as does the engine. Originally the pool of diesel sat under the engine in a sort of drip tray that holds a litre or two (that’s how I first saw it, during a daily inspection before a trip).
Now the boat is on the hard, and the pool of fuel is under the liner in the lowest part of the hull (below the gearbox).
So, I theorize that when the boats in the water, it sits slightly stern down. So the leak is caught by the gel coated liner and funneled aft to under the engine.
But now, with the boat on a cradle, the fuel is leaking forward. Somehow there is a hole or gap in the liner which the fuel now flows down. Once in the hull, the fuel then flows aft again, because the keel is shaped so all fluid will collect below where the shaft exits the boat.

 

[Bouba]

View attachment 126437

This is the corroded weld inside the aluminium fuel tank at 6 years old caused by water and fuel bug, the tanks were replaced with stainless to the same pattern.

Thanks for that, any idea of the costs involved (was it your boat)?

 

[Seastoke]

BOUBA we need daily updates , infact we could hold a beer and natter on your boat , and sending Brucek down in the bilge wht we drink your Red.

 

[Bouba]

BOUBA we need daily updates , infact we could hold a beer and natter on your boat , and sending Brucek down in the bilge wht we drink your Red.

You can drink it if you light but be warned it’s not red. It’s white diesel.
There is no update because it’s been raining and very windy. But I’m hoping that the forecast is right and I can go tomorrow afternoon to take a look

 

[Mistroma]

You can drink it if you light but be warned it’s not red. It’s white diesel.
There is no update because it’s been raining and very windy. But I’m hoping that the forecast is right and I can go tomorrow afternoon to take a look

We'll try to be patient (and not too jealous if it's snowing here ). It will take a little while to ensure the leak stops once you disconnect the pipes from the tank. If it continues and you get more than a litre then it has to be the tank. I'd be tempted to pour in another 20 litres if the leak does stop several days after you disconnect the pipes. That would confirm that the level hasn't just reached the level of hole. Lack of any leak at that point means you need to look harder at everything outside the tank. Downside is that it will be harder unless you start engine & generator to get fuel flowing again. I'd suggest just connecting and starting the generator first.

Might keep you busy for quite a bit longer as sod's law says the leak will be from the last thing you check.

 

[Bouba]

We'll try to be patient (and not too jealous if it's snowing here ). It will take a little while to ensure the leak stops once you disconnect the pipes from the tank. If it continues and you get more than a litre then it has to be the tank. I'd be tempted to pour in another 20 litres if the leak does stop several days after you disconnect the pipes. That would confirm that the level hasn't just reached the level of hole. Lack of any leak at that point means you need to look harder at everything outside the tank. Downside is that it will be harder unless you start engine & generator to get fuel flowing again. I'd suggest just connecting and starting the generator first.

Might keep you busy for quite a bit longer as sod's law says the leak will be from the last thing you check.

If it is the tank, I guess the higher the hole the better (my luck would probably mean it’s at the bottom ??)

 

[MapisM]

I guess the higher the hole the better

That's 6 of one and half a dozen of the other J, sort of.
I mean, I still find it weird that such relatively new tank is leaking, and of course I wish you it isn't.
But should this prove to be the case, I'm afraid that patching the leaking spot could only postpone some more radical surgery.
In fact, if the welding and/or the materials are not appropriate, more than likely it's just a matter of when and from where it will leak again, not of if...

 

[PCUK]

Aluminium tanks become porous over time and are then scrap. Personally I would replace the tank.

 

[Bouba]

The rain has stopped and the sun is shining but the sky still looks ominous in the distance. If it stays dry I will go to the boat after lunch

 

[Seastoke]

The rain has stopped and the sun is shining but the sky still looks ominous in the distance. If it stays dry I will go to the boat after lunch

Isn’t the tank inside

 

[Bouba]

Isn’t the tank inside

Ok, this is the situation....the boat yard is unpaved, it’s gravel, it’s mud, it’s puddles. My car is brand new. My car is clean.
Also I am nursing my back after slipping down the outside stairs in the rain (I am feeling a lot better, thank you all for your sympathy (I mean that sincerely) touch wood). The boat is on the hard. The ladder has to come out of the car boot and be set up and I have to climb it. When all is wet an slippy I don’t feel good (flashbacks, post traumatic stress). Today is now good but lots of water came down yesterday, last night and this morning so the wife has persuaded me to go tomorrow morning instead. It didn’t take much persuading to be honest ??

 

[Seastoke]

Ok, this is the situation....the boat yard is unpaved, it’s gravel, it’s mud, it’s puddles. My car is brand new. My car is clean.
Also I am nursing my back after slipping down the outside stairs in the rain (I am feeling a lot better, thank you all for your sympathy (I mean that sincerely) touch wood). The boat is on the hard. The ladder has to come out of the car boot and be set up and I have to climb it. When all is wet an slippy I don’t feel good (flashbacks, post traumatic stress). Today is now good but lots of water came down yesterday, last night and this morning so the wife has persuaded me to go tomorrow morning instead. It didn’t take much persuading to be honest ??

why dont you just put your engine fuel pipe in to the bilge , one big tank

 

[Bouba]

why dont you just put your engine fuel pipe in to the bilge , one big tank

If the boat was in the water I would do that and run the engine at idle until all the fuel was used up so it wouldn’t be wasted

 

[Bouba]

This morning’s update
There wasn’t as much fuel to pump out as before





That container of fuel still had a couple of inches in it from last time. I guess that there’s a litre extra which is way down on its normal flow. My fuel gauges (for what they are worth, never found them that useful before)
Still, fingers crossed
The fuel is definitely not flowing aft from the tank. It must be forward then under the liner and in the hull and then aft.
It’s so cold and windy. I’m sitting in the toasty Tesla and I am calling it a day. I will go back in a couple of days and check if it had truly stopped flowing

 

[benjenbav]

Would it be a false economy to pay a mechanic to go and check it all out?

It sounds grim having to manoeuvre over a wet step ladder with a bad back and try and squeeze into spaces not designed for those of mature years, all whilst ingesting the foul smell of unburned diesel.

 

[Bouba]

Would it be a false economy to pay a mechanic to go and check it all out?

It sounds grim having to manoeuvre over a wet step ladder with a bad back and try and squeeze into spaces not designed for those of mature years, all whilst ingesting the foul smell of unburned diesel.

You are absolutely right !
Beneteau have been informed but they are as always slow to respond. We will call them again on Tuesday. It’s very difficult to get hold of them during Paris Boat Show week !

 

[Hurricane]

Ahh the Paris Boat Show.

About 5 years ago, I took my wife on a romantic trip to Paris.
No, Honestly, I didn't know that there was a Boat Show that week!!

 

[Bouba]

Ahh the Paris Boat Show.

About 5 years ago, I took my wife on a romantic trip to Paris.
No, Honestly, I didn't know that there was a Boat Show that week!!

It’s actually a nice show, like Earls Court used to be