Age Old Questions: Keep Fuel Tanks Topped Off or Run Them Down?

[Passages]

The fuel truck was at the marina yesterday. This lead to the inevitable dockside debate of keeping tanks full or letting them run down adding fresh fuel on an as needed basis.

For me, I only turn over about 1500 gallons of diesel per year. My tank holds 1100 gallons. My diesel is delivered with Valvetec.

My observation of the Racor sediment bowl reveals no water but a significant quantity of "tar balls". I suspect these balls are byproducts of old fuel.

So I am inclined to keep my tanks between 1/4-1/2 in an attempt to minimize stale fuel. Dockmates are calling me foolish but what do you guys think?

 

[Boatsb]

Tar balls are muck in the tank and should be cleaned out.

1500 gallons is OK for the years turnover and circulating the fuel more often is as helpful as burning it.

Valveteck is junk.


https://www.jatonkam35s.com/DeuceTechnicalManuals/Diesel_fuel_additive_test.pdf

 

[Freestyle]

Love the fuel dock argument because no winners or losers and no political parties are involved.

I am in your camp. I estimate consumption with a safety factor and add that to tanks that are 25% full. My theory is that the DD's return so much fuel that after a cruise the fuel in the tanks has been through the Racors a few times.

I live in Florida where the temperature change doesn't lend itself as well to the condensation in the tank argument.

So I run around with less than full tanks saving money and only about half the people at the fuel dock think I am an idiot. That's a better approval rating than any politician has.

Bruce
Freestyle
1986 62 DCMY (54MY with 8 foot cockpit ext.)
Tampa

 

[RonNP]

I keep my tanks 100% full while at the dock. I put Biobor in them if I won't be cruising for a couple of months. I do this mainly out of paranoia that one day the BIG ONE will hit California and i want to make sure I have enough fuel to get out of the state if needed and have enough diesel on hand to run the generators so I'm not living in the stone ages.

 

[SKYCHENEY]

I base my fuel purchases on price. If it seems really low, I fill them up. If not, I just put in what I need. As for winter storage, it goes into storage with whatever is in there. Some years its near full, other years its near 1/4. Never a problem in 16 years so I'll keep doing it this way.

 

[SEVEN]

I’m like Ron I keep them full. I ran out of fuel once (owner error) and will never find myself in that spot again. Filters are clean as new so that’s not an issue.

 

[Passages]

I think the answer To this one is it does not make a hoot of difference either way.

Some dockside experts just have to have an opinion on everything an like to argue about nothing.

 

[Pascal]

I try not to keep diesel for more than 6 months. Up north where you get condensation in the tank I can see why they s want full tanks but in Florida it isn’t an issue.

In hurricane season... I try to keep the tanks full so I can run if needed

 

[Photolomy]

Sometimes full, sometimes half. Depends on the last trip. I try to at least keep them half full in case I need to go somewhere or move the boat. There have been times when the fuel dock has been out of order. Half a tank will pretty much get me to any marina within a day's cruise if need be.

 

[Photolomy]

Just a data point. When I bought the boat last year, the fuel had been in it for 4+ years. 3/4 in one tank and 1/2 in the other. Before the 1800 mile trip down here, we changed all the filters etc, but not a single issue with the fuel. Of course, we filled the tanks a few times during the trip (19 days) and when it got here changed all of the filters again.

 

[krush]

For me, I only turn over about 1500 gallons of diesel per year. My tank holds 1100 gallons. My diesel is delivered with Valvetec.

You live on your boat in the boating capital of the world (with year around boating season) with tons of destinations within a few hours, and you only burn ~1500 gallons a year! You should be ashamed of yourself...maybe you should be kick out of this close group of Hatteras owners.....oh wait! hahahah

 

[Scarlett]

I have always thought that metal tanks are more prone to condensation than our fiberglass tanks, no scientific studies involved just a feeling. John

 

[sgharford]

For me it's more of a weight thing. On a 43DC the fuel tanks (2 x 200 gallons) are all the way at the stern. I find if I keep more then 3/4's full it's struggle to get her up on a plane, even with full trim tabs. I always run on plane, about 17+ knots, so I'm happiest running 1/4 to 1/2 tank, but always fill up to 3/4 mark when time comes. I go about 9/10th full for winter storage.

 

[luckydave215]

I'm with Ron et al in that I live in earthquake country. I keep a lot of fuel on board when at the dock, I try not to let it get below 1000 gallons.
I can (just) make Cabo with full tanks.

 

[Boatsb]

I try to keep 250 to 275 gallons in mine. That's enough to get me to next stop if necessary and I can pull from the tanks for my truck if needed.

Keep in mind I hold 300 gallons total.

As to 1500 gallons a season. It would be nice. That's a lot of time I just dont have lately.

 

[dsharp]

The fuel truck was at the marina yesterday. This lead to the inevitable dockside debate of keeping tanks full or letting them run down adding fresh fuel on an as needed basis.

For me, I only turn over about 1500 gallons of diesel per year. My tank holds 1100 gallons. My diesel is delivered with Valvetec.

My observation of the Racor sediment bowl reveals no water but a significant quantity of "tar balls". I suspect these balls are byproducts of old fuel.

So I am inclined to keep my tanks between 1/4-1/2 in an attempt to minimize stale fuel. Dockmates are calling me foolish but what do you guys think?

A significant number of "tar balls" isn't a good thing