On Nov 26, 6:40�pm, "Dave Isherwood" wrote:
Good Evening's All - Much appreciate (incremental) remedies.

Comfit is a Carver 520 with 2*400 gal. tanks. There are two vents on the
sides (2 per each) that will vent diesel after filling 10 gal. into 200
gal void.

I just spent 1.5 hours putting 200 gal. into each of two 400 gal. tanks. We
had to put a cloth over the two vents to stop diesel going into the water.

Do you have any suggestions on how I could fix this?

Dave

Larger diameter vent lines.

Any time you add fuel to a tank faster than you can evacuate the
displaced air, you wind up with a pressurized tank and that can begin
dribbling fuel through the vent at an early stage of the fill up.

How is your fill pipe configured? You might be able to relieve some of
the pressure by sticking the nozzle only part way into the fill pipe
and allowing some of the displaced air to escape at that point.

A third consideration is the baffling in your tanks. It sounds like
you waited until you were on fumes to fill up,-if you put 400 gallons
of fuel into a 400 gallon system. Air can build up behind one of the
baffles that were installed to discourage your fuel from sloshing
around with wild abandon. As you fill up the tank, you can get to a
point where an glob of air finally gets squeezed out and that can
carry droplets out the vent.
If you are amost completely empty, stop pumping after 15-20 gallons
and rock the boat for a few seconds to "burp" the baffles. One
advantage of filling up before running entirely out is that there is
less air to manage.

Finally, what do you mean by putting a rag "over the vent"? You
certainly don't want to impede the passage of air through the vent. My
tank vents are through the gunwales, and are situated parallel to the
surface of the water. I hold a "diaper" (fuel abosorbing pad) *under*,
not over the vent when fueling. By listening to the tone of fuel
flowing into the filler pipe its possible to get a sense of when the
tnak is nearly full, and then pump very, very slowly. At the very
most, you might get a half teaspoon of diesel on the diaper if you
aren't pumping too fast.