Fuel Management During Winterizing

[IOLANI]

So I've heard it said more than once that you should top off the fuel tanks before winterizing...the theory being with the tanks full there is no room for moisture/condensation to form. The drawback in my case is that it leaves me with 800 gallons of fuel come summer and I probably only burned 300 of it this year on day trips. Now heading back to storage again and so topping it off will start that cycle all over again. The end result I fear will be an accumulation of "stale" fuel which never gets run out and replaced with fresh.

Soliciting opinions here...should the tanks be topped off or it's not necessary?

Also... planning on adding some of the product pictured here to each tank.

Any negatives associated with it ? (Detroit 8V92ti's)

 

[jim rosenthal]

I've used their products in diesels (land and marine) for years and I think they are very excellent. I top off the tanks, too.

 

[SKYCHENEY]

Studies have shown that the volume of air in the tank is so small that there is no measurable difference in condensation full or empty.

 

[Bob Bradley]

As long as there's no water in there, I wouldn't be worried about it. Diesel doesn't really break down. When I bought my 45, it had 140 gallons of diesel in an auxiliary tank. It was already there when the previous owner bought it 7 years earlier. I transferred it into my main tanks and never had any issues whatsoever with it

 

[whoover]

I have never heard of stale diesel fuel, is it possible?

Walt Hoover

 

[Avenger]

Studies have shown that the volume of air in the tank is so small that there is no measurable difference in condensation full or empty.

Right. The only possible logical argument for topping off the tanks is that it is unlikely that fuel will be cheaper next season.

I have never heard of stale diesel fuel, is it possible?

Walt Hoover

It can, but it takes a REALLY long time before it becomes unusable. Eventually all the volatile elements will evaporate and the fuel turns into varnish. I've seen one case where an engine wouldn't start because the fuel was so stale it wouldn't ignite. It fired right up on fresh fuel. The fuel was well over ten years old.

 

[Sadey]

Heated storage?

 

[bostonhatteras]

I have never heard of stale diesel fuel, is it possible?

Walt Hoover

Four year duration refit and engines ran just fine on that four year old fuel. two years on hard with minor start ups, third year in water for a month to ensure stuff still worked. Fourth year splash and ran great. No smoke, no long starts. No issues with condensation on center or st'bd tanks, port tank always had issue due to leaking deck fitting but resolved now with new deck fittings and fill hoses.

 

[bostonhatteras]

Right. The only possible logical argument for topping off the tanks is that it is unlikely that fuel will be cheaper next season.




It can, but it takes a REALLY long time before it becomes unusable. Eventually all the volatile elements will evaporate and the fuel turns into varnish. I've seen one case where an engine wouldn't start because the fuel was so stale it wouldn't ignite. It fired right up on fresh fuel. The fuel was well over ten years old.

I read somewhere that starting fluid is pretty much the volitile compound that evaporates out and is the additive that rejuvenates old diesel, obviously not from a varnish but aged. The article said to empty a can into the tank and it brought back the cetane levels. Always wondered about the accuracy of that.

 

[bostonhatteras]

Not the article I read years ago but interesting nevertheless. This paper states that pure diethyl ether has a cetane rating of 125 https://grdjournals.com/uploads/article/GRDJE/V01/I05/0005/GRDJEV01I050005.pdf

 

[TomT13]

I usually go through a fair amount of fuel every year so my tank gets burned several times a season. I do use an additive every fall at layup. Recently my repower took 1.5 years and the fuel was fine especially with the lower micron filters for common rail engines I had no issues.

 

[IOLANI]

Thanks guys for all the input. There seems to be a whole cottage industry now built around “ fuel scrubbing” or “fuel polishing” . The captain I hired to bring the boat up from Florida to NJ insisted I perform this operation before he would take the trip.(The boat had sat unused for several years). I guess this is what put the idea in my head.

 

[ageless]

absolute best bang for your buck https://www.opti-lube.com/categorie...sel-fuel-additives-yellow/3737200000001113190

 

[rsmith]

Condensation doesn’t form in storage as much as running the boat. When you’re running 2 things happen. The fuel is returned to the tanks pretty warm even with the cooler. If you run for any prolonged period and feel the tanks they’re a lot warmer than the surrounding fiberglass. Second as the tank is emptying wet humid air is drawn through the vents replacing the fuel used. To add insult to injury these vents are mounted outside the hull sides where spray and probably the most moisture laden air exists. After the run the tanks and air cool and all that saturated air starts to squeeze out the water droplets. The only way to stop this is to fill the tanks right after each run.
As far as how long the fuel lasts. The famous NORAD facility deep under Cheyenne mountain has millions of gallons of diesel stored in limestone caverns. Pumped there in the Cold War 50’s. Up until it was shut down a few years ago they routinely ran giant generators off that fuel that was 60 years old or so.

 

[Captain Ralph]

To much reliance on snake oils, no trust in water separation filters and not enough hours on your boat.
Ya got to go water skiing more during your better season,, burn some fuel....

 

[IOLANI]

Thanks for the info Scott.

I hear ya Captain Ralph. This year consisted mostly of 4-5 hour day trips, maybe 15 of them for a total of about 60-70 hrs. I've had boats since the mid 70's but the '54 MY was a big jump up for me. A lot of this was Captain's training just getting familiar and comfortable with the boat.

As far as the mechanical end of it I try to do whatever I can myself and so I try and draw on the experience of others to avoid those costly "rookie mistakes".