How full do I fill my diesel tank?

[agilmore]

Newbie question:

Everyone says keep my fuel tank full so it doesn't collect water. On my cars I fill them until the pump clicks off. this fills the tank and the "fill pipe". No problem: if the fill pipe happened to leak a tad (aging hose, loosening clamps, other?), the fuel drips on my parking pad, and I would fix it.

If this were to happen on my Tartan, the fuel would run down into the bilge and stink up the cabin, and probably take a full season for the smell to go away.

The above scenario hasn't happened yet, but I am getting ready for a winter haul-out and I was thinking that this could be an issue.

So, am I being overly cautious, or should I just fill the tank til the pump clicks off?

If I should stop short of filling the "fill pipe", how would I do that?

Alan

[Kettlewell]

Watch out! A lot of marine fuel pumps put out a lot of diesel fast. It is very easy to be happily pumping away only to have the stuff back up the hose and shoot all over the deck and you. This can happen fast, because the air vent line is usually too small, and the amount of fuel going in ends up pressurizing the air, which helps to shoot the diesel back up and out of the fill. On one boat I had I could hear the metal tank go boom when the fuel reached the top. On my current boat I listen for the change in sound coming from the vent line--the pitch goes up as the fuel rises. After some bad experiences I try not to top it all the way up. If you wish to do so I recommend using the fuel dock hose most of the way, and then topping off the last bit from jugs so that you can do it slowly and in control. And, you are correct, a leaky fitting somewhere between the tank and deck can create a mess--you can imagine how I found that out.

[Cheechako]

Yes, fill the last amount slowly.... if possible. More often then not, fuel spews out the vent tube into the water and looks like a major spill. Have someone hold an absorbant pad against the vent fitting. just fill until it clicks off... but it can be misleading..... every boat is different. The pump may click off before you are full, or it may not click off at all and come gushing out the fill fitting. Or , just as you are nearly full, the tank may go "boing" (oilcanning, meaning one side flexes out) and then you have more space to fill or a mess... Get to know your particular boat. Aint boating fun?! Frankly, I've never been convinced having a full tank of old fuel is better than having a partially empty one.

[jackdale]

Listen for the fuel to "gurgle" and then quit. Never wait until it clicks off.

I would also recommend that you keep carefully track of the engine hours and the fuel intake. Calculate your hourly fuel use and use that as a guide to filling your take. You can also use the following as a guide:

Fuel Consumption Rates – Diesel 0.1 liter/hp/hr, Gasoline 0.3 liter/hp/hr:

A full fuel tank will lessen the amount of condensation that occurs with heating and cooling, and resulting changes in relative humidity.

[Rhapsody-NS27]

take your time on this. You don't want to be responsible for accidental spilling into the water.

[Kettlewell]

take your time on this. You don't want to be responsible for accidental spilling into the water.

My fuel fill is on deck and I keep a large oil absorbent pad downhill from the tank fill in order to catch any spills. A winch handle can keep it from blowing away if it is windy.

[Rhapsody-NS27]

Originally Posted by Kettlewell

My fuel fill is on deck and I keep a large oil absorbent pad downhill from the tank fill in order to catch any spills. A winch handle can keep it from blowing away if it is windy.

The pad is a good idea. my fuel fill is on a cockpit seat and right below it is a couple cockpit drains. I have some of those pads I might give that a try myself. Thanks.

[Cheechako]

Originally Posted by jackdale

Listen for the fuel to "gurgle" and then quit. Never wait until it clicks off.

I would also recommend that you keep carefully track of the engine hours and the fuel intake. Calculate your hourly fuel use and use that as a guide to filling your take. You can also use the following as a guide:

Fuel Consumption Rates – Diesel 0.1 liter/hp/hr, Gasoline 0.3 liter/hp/hr:

A full fuel tank will lessen the amount of condensation that occurs with heating and cooling, and resulting changes in relative humidity.

Listening for the gurgling is a good idea, however a lot of boats gurgle the whole time, so listen for subtle changes.

[bobconnie]

If ya can put a drain cock at the low spot of the tank, most all of your problems with condensation would be fixed ! (if ya drain the water out of the tank that is LOL) Ive done this on all the boats Ive had or repaired over the years and it sure works for me !! Hard to make sludge if the water gets drained ! Just a thought ! I always fill my tanks as slow as the equipment Im useing will allow me to, and NEVER leave it unattended while filling !! And now adays ya sure need absorbent pads !!

[thinwater]

Vent filters are another option. Practical Sailor will be publishing something on this in a month or 2.

In a nut shell these are filters that use silica gel to dry the air before it enters the tank. They are also applicable to gasoline tanks. Though testing continues, the life expectancy if properly installed seems to be about 2 years.

H2Out® AVD3 ~ Product ~ H2Out

This is a new area and there are few competitors, but there are also DIY options: Sail Delmarva: Gasoline and Fuel Tank Vent Filters

There are a number of installation concerns, primarily that you MUST have a fuel/air separator between the filter and the tank and that it must be installed at a high point.

____________________

The tank does not have to be full to limit breathing, just mostly full. There is no need to fill it up into the hose.

This won't solve problems with rainwater leaks and wet fuel delivery.

Spring is the condensation season; cold water and tanks + warm air. Yes, we have been able to reproduce condensation in diesel tanks under controlled conditions, contrary to some that argue that it is not possible. We have NOT been able to cause condensation or separation in e-10 tanks under realistic field conditions; we only saw that in the fall (cooling temperatures) where leakage (even if very limited) had also been a factor, or in very small (2 liter) tanks.

As all new gasoline powered boats with installed tanks are now coming with carbon canisters, this is something that will soon be commonplace.

[agilmore]

Great inputs.

Right, I will be careful to just fill the tank and not the fill pipe.

Thank you,
Alan

[Allan S]

Thanks from me too, I just got my first inboard and have not had to fill it yet.

[perchance]

Google Barton Marine fuel tank whistle.

[xymotic]

Best thing I ever bought on my last boat was a $30 vent line whistle. It would change tone as the fuel got near giving me time to slow down and when it stopped making noise the tank was totally full.

OCEAN ACCESSORIES Fuelwhistl at West Marine

[agilmore]

Gotta git me one of those whistles

Thanks,
Alan