Bad fuel tank installation design - solutions?

[lw395]

Thanks for all the comments and ideas.
Charles is right, a narrow vertical tank would do it, but very difficult.
A small buffer tank would also do it but there is a problem of little room below the main tank and I am nervous of putting in a connection at the bottom. Difficult to seal with high integrity to a blown PE (or PP) tank. All current connections are on a top plate.
A pump to the buffer tank is extra complication, cost and something else to go wrong.
Lots of head scratching needed.
I'm really p'd off that an expensive, not bottom of the market, boat only 8 years old was done like this. I wonder if current production (now by Hanse) is the same?

It's fairly standard I think.
In the name of preventing the engine picking up the bug from the bottom of the tank.

 

[NormanS]

It's fairly standard I think.
In the name of preventing the engine picking up the bug from the bottom of the tank.

What? Having a long shallow tank, mounted athwartships? I hope not. What sort of designer came up with that idea?

 

[garvellachs]

My boat has a standard Vetus fuel tank which is 800mm long x 400mm wide x 330mm high, capacity 88L like this http://www.vetus-shop.com/vetus-fuel-tank-diesel-88-litre-p-1794.html
The pickup is 200mm from one end. It's a vertical dip tube going down to 1cm above the flat bottom.
Unfortunately the tank is fitted lengthways across the beam - a serious design error in my view.
The result is that even with 20L of fuel in, a heel angle of 20 degrees will cause it to suck air and stop the engine. It's happened and caused an anxious few minutes.
So the effective fuel capacity is reduced to about 60L.

Any comments and other ideas appreciated.

You invited comments: 20 deg heel is quite a lot to be running the engine with? Are you motor-sailing? I doubt that your engine will enjoy being angled that much for extended periods (might be worth checking the manual). If there's enough breeze to heel the boat 20 deg under sail do you really need the engine on? Alternatively, if the breeze is heeling the boat 20 deg with no sail up, do you really want to be motoring with only 20 litres of fuel or less than a quarter tank except in dire circumstances? Those are exactly the conditions when all the crud in the tank gets stirred up and blocks the filter anyhow.

If the tank is only 88 litres you probably don't have a huge engine, so you have more than 24hrs fuel there - why not just get a jerry can and top up the tank more regularly so that you don't have to set out with a low fuel level?

 

[geem]

You invited comments: 20 deg heel is quite a lot to be running the engine with? Are you motor-sailing? I doubt that your engine will enjoy being angled that much for extended periods (might be worth checking the manual). If there's enough breeze to heel the boat 20 deg under sail do you really need the engine on? Alternatively, if the breeze is heeling the boat 20 deg with no sail up, do you really want to be motoring with only 20 litres of fuel or less than a quarter tank except in dire circumstances? Those are exactly the conditions when all the crud in the tank gets stirred up and blocks the filter anyhow.

If the tank is only 88 litres you probably don't have a huge engine, so you have more than 24hrs fuel there - why not just get a jerry can and top up the tank more regularly so that you don't have to set out with a low fuel level?

If you are motor-sailing into a chop or foul tide, 20 degrees of heel wouldn’t be exceptional. Since 20 litres is a little under 1/4 full it’s not an unreasonable request to be able to use the engine in these conditions. I am not aware of a marine diesel that won’t run all day at 20 degrees of heel. If there are any that won’t do this then they have no place on a yacht, in my opinion. If there is a crud in the tank then that another completely different thread. There shouldn’t be crud in the tank! But the tank design should allow for that eventuality. Poor and unacceptable design with little opportunity to resolve satisfactorily it would seem

 

[Plevier]

garvellachs

Your comments are valid but out of context.
On the occasion when the engine died, we had been racing round the cans in pretty rough conditions and were then motoring back with no sail in a lumpy sea in a stiff breeze and were about to enter harbour. It was not a pleasant few minutes while I wondered what was wrong, took a guess from the engine behaviour and bled the system to get it going again. We had thought a 1/4 full tank was more than enough for local use! Afterwards I looked at the tank installation with a fresh eye and the penny dropped. Since then we have tried not to get much below 1/2 full.
Then two weeks ago, after a long crossing against unforecasted headwinds (fcst was 4-5 W-SW and we got a 5 from the S), we found ourselves approaching l'Aberwrach with about 15L on the gauge and praying for little swell. That should have given us 6-7 hours (D1-30), but with a swell might have given us 0! Started with tank full, the spare can was empty because we couldn't take red to France and that was all we could get. Yes we had contingency plans with sail and anchor ready.
Topping up from a can on the sidedeck in rough conditions is not a very good idea. Seawater in the tank would not help.

 

[lw395]

What? Having a long shallow tank, mounted athwartships? I hope not. What sort of designer came up with that idea?

I meant having the pickup not reach the floor of the tank.
But when sailing other people's boats, I generally assume the engine may suck air if the tank is less than half full and it's really lumpy.
Once bitten as we say...