To empty, or not?

[Ink]

In this month's Yachting Monthly in the letters page there is a letter with the above title asking whether diesel tanks should be emptied over winter or not.

The gist of one of the respondents is that yachts carry such small amounts of diesel that tanks should be drained and left empty and refilled with fresh diesel in the spring.

It doesn't say what happens to the diesel that is drained off, but another respondent stated that for small amounts, disposal may be a safer option.

My tank is half full with about 70 litres of red diesel. I have no space to drain and either store it or dispose off it. Access to non road diesel would be a chore to go back and forward to the nearest filling station with a Jerry can and fill up with 20 liters a time (4 trips).

How does the panel suggest for disposal? There is a very handy drain nearby ?

Ink

 

[The Q]

FILL the Tank with Diesel to stop Condensation in the tank.. Add anti diesel bug treatment.. Then it will be fine.

 

[dankilb]

Brim the tank (help reduce condensation) and add some fuel treatment… can’t see the point in storing, let alone disposing, that amount of usable fuel

 

[dankilb]

Ha! Sometimes crossed-posts say it all ?

 

[Poignard]

In this month's Yachting Monthly in the letters page there is a letter with the above title asking whether diesel tanks should be emptied over winter or not.

The gist of one of the respondents is that yachts carry such small amounts of diesel that tanks should be drained and left empty and refilled with fresh diesel in the spring.

It doesn't say what happens to the diesel that is drained off, but another respondent stated that for small amounts, disposal may be a safer option.

My tank is half full with about 70 litres of red diesel. I have no space to drain and either store it or dispose off it. Access to non road diesel would be a chore to go back and forward to the nearest filling station with a Jerry can and fill up with 20 liters a time (4 trips).

How does the panel suggest for disposal? There is a very handy drain nearby ?

Ink

1. Lay your boat up in Hayling Yacht Company's shed.

2. Drain the diesel into a container.

3. Leave the container under your boat.

4. Someone will steal it.

That's what happened to me when I drained my tank and took it home to steam clean it.

 

[Tradewinds]

1. Lay your boat up in Hayling Yacht Company's shed.

2. Drain the diesel into a container.

3. Leave the container under your boat.

4. Someone will steal it.

That's what happened to me when I drained my tank and took it home to steam clean it.

when I did that (c200L in a big plastic drum) I scrawled on the drum in BIG letters "Bilge Water" with a magic marker.

Still there x months later

 

[Sandy]

I empty my tank, run low at the end of the season. As I use white diesel I use it in the car.

Why have diesel hanging around in tanks when the manufacture says it has a shelf life of six months?

 

[dunedin]

FILL the Tank with Diesel to stop Condensation in the tank.. Add anti diesel bug treatment.. Then it will be fine.

Actually the point of this and other articles is that this USED to be the recommended advice, but with the changes to diesel formulation and increased biofuel content (which may be in diesel claimed not to have this) it is now a moot point whether better to fill up and have old diesel in the spring, or run low and buy fresh diesel in the spring.
The ideal is now suggested to be drain and keep tank empty - though not clear how this can be practically achieved.

Having got diesel bug last winter having filled the tank in November, and having used treatment diligently since new, this year I have not topped up the tank and going to try topping up with fresh fuel in the spring.
As others have noted, not possible for many of us to drain and ”dispose of” 70-100 litres of diesel tank contents, and of course cannot run too low and be safe to use at sea.

 

[WFA]

I have a 300+ litre tank which is filled at the beginning of each season to fuel an engine that consumes 2.2 litres per hour so towards the end of the season I try not to fuel more than is necessary.
Historically I would brim the tank each winter however on returning from a long cruise several years ago I topped the tank mid season and found the the tank was leaking from many small perforations which had developed unnoticed an inch on so from the tank top. Conclusion - a) condensation rots mild steel tanks when they are not 100% full ie most of the year; b) finding containers and decanting 300 litres late on a Saturday afternoon while on a mooring is not an experience to be repeated.
Now, using a portable inline pump, I transfer what fuel is left in the tank via the onboard separater/filter into 20 litre containers and decant this to fuel my motor launch which remains in use throughout the winter.
To enable winter /spring berthing of the yacht and periodic engine running I hook up an adapted 20 litre outboard engine fuel tank.
In the spring I change the fuel filters and fuel up with fresh diesel which is then dosed for good measure and remove the temporary tank.
I appreciate that this is not a solution for everyone but my recommendation is to keep an eye on fuel needs towards the end of each season (carry a spare can of white diesel if necessary) and drain the tank when laying up.

 

[Graham376]

Why have diesel hanging around in tanks when the manufacture says it has a shelf life of six months?

In which case they're wrong. My 3/4 full tank's content (E5 road diesel) is mainly 3 years old, with some of it 5 years. Started and ran fine a couple of months ago. It's dosed with Fuel Set.

 

[Clancy Moped]

As above, fill to the brim to stop condensation, and do the same with your black holding tank if you have one. Then swap the deck fitting filler caps over. A nice shock if someone tries to syphon off your diesel.

 

[Sandy]

In which case they're wrong. My 3/4 full tank's content (E5 road diesel) is mainly 3 years old, with some of it 5 years. Started and ran fine a couple of months ago. It's dosed with Fuel Set.

Would you use fuel that old in your car?

 

[Graham376]

Would you use fuel that old in your car?

I would try a small amount first to see if car's modern engine would be OK on it. My car was last filled in May before we left for the summer so now nearly empty but, just like the boat, it's running fine after more than 6 months. Due to Covid lockdowns, there will be many boats with old fuel in the tanks and I bet they will run fine unless they have bug of course.

 

[Daydream believer]

I have 7 - 20 litre cans of while diesel at home an a full tank ( 45 litres) I purchsed when the rate was a bit lower. I think the age thing is b..x. I just keep them topped up when visiting the garage to fill my van. If sailing abroad I buy additional fuel & make sure I have receipts for customs. Particularly France because the customs officials have a fixation with me

I had a small in accessible area of my 1 acre builders yard, that was overgrown for 20-25 years. when we decided to clear it, we found a 4 inch Pegson pump, a Greens 6cwt roller a Benford & a Millars concrete mixer. 2 of them had no caps on the fuel tanks.
The Millars mixer needed bleeding. All the other items started almost first time. The only panic was when the Benford started & we realised the handle was rusted in place & would not come off. We had to wait for it to run out of fuel because we could not open the lid to flip the decompressor to stop it.

 

[PetiteFleur]

I usually keep the tank pretty full at layup time but do add MR16 fuel conditioner as I run the diesel heater everytime I visit in the winter. I use road diesel as my boatyard does not sell red to leisure boaters. Not had a problem for several years.

 

[V1701]

I'm sure somebody will correct me if I'm wrong but if everything (i.e. the fuel itself, the tank, the surrounding air &/or whatever else surrounds the tank) is at the same temperature then theoretically there should be no opportunity for condensation to develop. In practice in your position if I had a metal tank I'd be tempted to top up, plastic tank I probably wouldn't bother, the last thing I'd do is drain it all off and even if I did drain it off would not dispose of it...

 

[NDG]

Never drained ours in 20 years. Never had a problem.

 

[AngusMcDoon]

I'm sure somebody will correct me if I'm wrong but if everything (i.e. the fuel itself, the tank, the surrounding air &/or whatever else surrounds the tank) is at the same temperature then theoretically there should be no opportunity for condensation to develop. In practice in your position if I had a metal tank I'd be tempted to top up, plastic tank I probably wouldn't bother, the last thing I'd do is drain it all off and even if I did drain it off would not dispose of it...

Theoretically, I suspect that you are right...

The Myth of Condensation in Fuel Tanks by David Pascoe: Boat Maintenance, Repairs and Troubleshooting

David Pascoe seemed to think that vents and leaking filler caps were the culprit. I suspect that he was right too.

 

[shortjohnsilver]

So, those of us that have plastic integrated tanks need not worry?
I mean I appreciate that a metal tank is more likely to create conditions for condensation and had always understood that black plastic tanks, much less so, hence I’ve never drained down and had no issues at all.
Since owning the boat - 10 yrs - I’ve used white diesel and keep twenty litres available at any time aboard. This too can sit for over six months before using it. Never seen water in the filters either.
I am interested though in diesel treatments although never applied. Perhaps I should add something but so far no issues at all so haven’t gone down that route. Should I?

 

[oldgit]

MoBo owner with tanks capable of holding 150 gallons.
Never once bothered about it . Sometimes the tanks are nearly empty sometimes full or nearly full.
Boat is always afloat and frequently used in winter.
Fuel comes from our on site club bunker and is dosed with some magic goo or other, suspect in tiny amounts.