Originally Posted by a64pilot
A clean dry tank will most likely never accumulate any water
or any other problem, it’s the ones that may have several gallons of fuel
left in it and may have significant sludge etc on the bottom that may be a problem.
Sail conducted a test to bust the myth of tank condensation
and had an empty tank sit for considerable time and subjected to daily heating
and night time cooling
and after an extended period it never accumulated even a drop of water
I believe his test to be correct, but may not be applicable to a fuel tank
in it, the difference in my opinion is the fuel, fuel can absorb water, and can when conditions change drop that water out of suspension, so while I agree an empty tank won’t condense water, it’s possible for one with fuel to do so, possible doesn’t mean will of course, just it could.
However the desiccant filter will prevent any moisture from getting into the tank to start with, or I guess close the vent off, it seems it won’t have enough pressure change to matter.
Closing the vent off would be very simple, just stick a ball valve in line.
The myth of tank condensation
continues despite Maine
Sail's having thoroughly busted it.
Water in fuel tanks
either comes on board in bad fuel, or comes from leaky deck
fillers are the work
of the devil. If you have these things, be fanatical about o-ring condition and correct tightness.
fuel (so long as it has no bio in it!) is a quite stable substance, but it does deteriorate, and it does absorb water from the air. Leaving more fuel in the tank than you need is just more fuel to deteriorate and absorb moisture.
My father was a firm believer in the old tank condensation canard. Every single
time when we came back from a cruise
, we would fill the tank. Yet -- he suffered from regular bouts of diesel
bug and water in the fuel for decades. I have no doubt it was the deck filler.
In this boat
, over 11 years, the tank is mostly empty in the winter time. Now, I use the boat year around, but less in the winter. Never a drop of water in the tank, despite the famously rainy, humid, condensatious weather
of our usual winter home in Old Blighty. I do inspect the tank regularly to be sure, and I'm careful where I buy fuel, avoiding bio like the plague, and avoiding low turnover outlets.
AND -- I don't have a deck filler. The fuel filler is located a couple feet above deck level, in the side of the house.