For those that remember, at year 8 we opened all four of our fuel tanks and checked for water... found none. Now, 5 years later, we opened the tanks again and again found no water in any of the tanks. To reiterate, we use two of the tanks all the time, only adding diesel when the tanks are low. The other two tanks we only fill when we need the range provided by these additional tanks, otherwise they stay empty. The O-rings on the deck fills are checked for cracks or breaks every time we remove the cap, and the caps are kept screwed down tight. Vents to the tanks are designed and installed to eliminate back flow of water into the tanks. So, once again we question the validity of the often-stated premise of keeping internal diesel tanks full to keep moisture and water from collecting in the tanks. We suspect, if there is water in the tank that it comes from a bad seal on the deck fill, back flow from a vent, or from taking on a load of fuel that already has water in it. Any one think of other causes? *Rudy & Jill Sechez* *BRINEY BUG-a 34' Sail-Assisted Trawler * *850-832-7748* *trawlertrainingabc.com <http://trawlertrainingabc.com>* New Smyrna FL

Rudy: I have never given this a lot of thought but in 30 years of ownership of the same boat I have never had any water at all in my three tanks or in my 2 micron Racors. I found this article that supports your position. https://www.yachtsurvey.com/myth_of_condensation_in_fuel_tanks.htm Frank Burrows    79 43' Viking   Piney Narrows  Chesapeake Bay On 12/8/2019 3:51 PM, Rudy Sechez via Trawlers-and-Trawlering wrote: > For those that remember, at year 8 we opened all four of our fuel tanks and > checked for water... found none. Now, 5 years later, we opened the tanks > again and again found no water in any of the tanks.

Rudy, I agree. In 10 years after installing two new aluminum 160 gal tanks in Pooh, I never found any water. Even old cracked o-rings on deck fills should admit only tiny amounts of water unless there are puddles on the deck. My vents had a ball valve closure which I would close when the boat was out of service. Mark Richter > On Dec 8, 2019, at 5:02 PM, Rudy Sechez via Trawlers-and-Trawlering <trawlers@lists.trawlering.com> wrote: > > For those that remember, at year 8 we opened all four of our fuel tanks and > checked for water... found none. Now, 5 years later, we opened the tanks > again and again found no water in any of the tanks. To reiterate, we use > two of the tanks all the time, only adding diesel when the tanks are low. > The other two tanks we only fill when we need the range provided by these > additional tanks, otherwise they stay empty. The O-rings on the deck fills > are checked for cracks or breaks every time we remove the cap, and the caps > are kept screwed down tight. Vents to the tanks are designed and installed > to eliminate back flow of water into the tanks. So, once again we question > the validity of the often-stated premise of keeping internal diesel tanks > full to keep moisture and water from collecting in the tanks. We suspect, > if there is water in the tank that it comes from a bad seal on the deck > fill, back flow from a vent, or from taking on a load of fuel that already > has water in it. Any one think of other causes? > > > *Rudy & Jill Sechez* > *BRINEY BUG-a 34' Sail-Assisted Trawler *