Diesel question: keep it topped off or let it go down?

[Powercon Steve]

??? Don't you have to use Marine diesel??

[Nicholson58]

Originally Posted by Pelagic

I agree, there are other more important reasons to keep your tanks full. (Or Not!)

I think weekend racers probably only want minimum weight.

Cruisers with generators are more interested in costs and increased options to go to remote locations.
As fuel costs generally go up, it is a pretty safe bet to buy now if convenient, rather than later at a higher price.

The engine does not care hat the fuel level is. This is more a question of your convenience and cruising style. We hold 400 gallons in five tanks the boat weighs 40 tons. Fuel weight is not an issue. We live aboard. We by fuel where the bes price can be had. Many Caribbean countries offer duty free fuel and that is where we top off. We run a 1-micron polisher with moisture removal so I have not changed a Racor in four years. I have a feeling the fuel treatments are snake-oil so we use none.

[belizesailor]

The condensation debate aside, I like to leave the dock w full tanks...especially on older boats which likely have sediment in the bottom of the tank...because if you get in rough weather, there is a lot more churn going on in a tank with low levels and that churned up sediment can clog fuel filters.

Also, Ive had engines suck air on monos with offset tanks if heeled well over with low levels in tanks.

Depends too on the type of sailing the OP does. Just out for a day sail in benign conditions...no as much of an issue.

[belizesailor]

Originally Posted by Powercon Steve

??? Don't you have to use Marine diesel??

Of course! Im running a special on "marine" diesel today...drop by for some. 😆

[Stu Jackson]

Originally Posted by Dsanduril

If you don't sail like the Pardeys, and actually have an engine then the math to me works more like this - do you have enough fuel to get back to a nice, snug anchorage from the furthest part of your sail? Crossing oceans in a typical auxiliary sailboat this doesn't mean much, but for a summer coastal sailor I'd base my fuel storage on getting to the furthest point I usually sail, losing the mast, and being able to get back to someplace secure against strong wind and crappy seas (you did just lose the mast after all). Being able to jury-rig/fix things is great, but having the engine option in that moment is also of value (to me anyway).

Well put. In coming up the coast from SF to BC, we found one city had closed its fuel station. I did some very detailed calculations on fuel consumption and remaining fuel in order to assure continuity to the next available fuel and harbor. I have tracked my fuel consumption since 1998 and don't have a working fuel gauge and wouldn't trust it if I did.

[NYSail]

My opinion....... I use my fuel and never bring it above a 1/4 tank unless I’m going away. I have a great filter/water separator and by the way in the 15 years or so that I have been doing this I never have any water in the system. In winter I get tank as low as possible so that in spring I can add fresh fuel. Yes I know there are great additives and bio killers but I am a fuel purist. Never add anything except an occasional cetole booster.

Just
My opinion and practice.

Good luck!
Greg
(Probably tomorrow I will have a water issue)

[Panope]

Originally Posted by Pete7

Ah, but your yacht like mine lives in the water all year round. For the thousands of yachts in the UK which are lifted out each winter then temperature and air pressure changes occur daily. Warm air drawn into a cold tank condensates on the tank walls. However, as you said it's the filler which is the main culprit.

Interestingly the coding for a UK charter boat requires the vent and fill hoses to be fitted with a valves capable of sealing off the tank.

Pete

Panope's tanks are now 17 years old and have NEVER been empty and NEVER been more than half full. Boat has been on the hard for about 80% of that time (including each but one winter) in Washington State (a wet place).

Tanks vents are always open to the outside atmosphere.

Total water collected from these tanks amounts to a few drops. Maybe a teaspoon full.

(I replace the (flush deck) fuel fill cap O-rings every couple years whether they need it or not).

Steve