Winterization of Marine diesel tank and service of engine.

[CarlN]

I use a biocide (Biobar) everytime I get fuel but don't fill the tank for storage. I've been doing this for 20 years and never had a problem. A boat tank buried deep in a bilge with no exposure to sun doesn't change temperature much through the day.

If the fullness of the tank was such a big problem, wouldn't it happen during the summer as well as during winter storage? Best practice would then be to keep the tank full both summer and winter. I've never heard that recommended.

The Biocide stops any growth and the Racor collects any water (and I can't remember ever draining my Racor of water the next season despite not topping the tank in winter).

And by not filling the tank before storage, I get fresher diesel the next season which I think is more important than worrying about a bit of condensation that may or may not be happening. For environmental reasons, diesel today is a more complicated blend than it used to be and is not as stable (I always wait to fill in the spring until after the marina gets a fresh delivery).

 

[sailme88]

I use a biocide (Biobar) everytime I get fuel but don't fill the tank for storage. I've been doing this for 20 years and never had a problem. A boat tank buried deep in a bilge with no exposure to sun doesn't change temperature much through the day.

If the fullness of the tank was such a big problem, wouldn't it happen during the summer as well as during winter storage? Best practice would then be to keep the tank full both summer and winter. I've never heard that recommended.

The Biocide stops any growth and the Racor collects any water (and I can't remember ever draining my Racor of water the next season despite not topping the tank in winter).

And by not filling the tank before storage, I get fresher diesel the next season which I think is more important than worrying about a bit of condensation that may or may not be happening. For environmental reasons, diesel today is a more complicated blend than it used to be and is not as stable (I always wait to fill in the spring until after the marina gets a fresh delivery).

Guess being in RI you've never had frost on your windshield...

 

[dlochner]

I use a biocide (Biobar) everytime I get fuel but don't fill the tank for storage. I've been doing this for 20 years and never had a problem. A boat tank buried deep in a bilge with no exposure to sun doesn't change temperature much through the day.

If the fullness of the tank was such a big problem, wouldn't it happen during the summer as well as during winter storage? Best practice would then be to keep the tank full both summer and winter. I've never heard that recommended.

The Biocide stops any growth and the Racor collects any water (and I can't remember ever draining my Racor of water the next season despite not topping the tank in winter).

And by not filling the tank before storage, I get fresher diesel the next season which I think is more important than worrying about a bit of condensation that may or may not be happening. For environmental reasons, diesel today is a more complicated blend than it used to be and is not as stable (I always wait to fill in the spring until after the marina gets a fresh delivery).

Water vapor enters the tank anytime there is a change in air pressure in the tank. The air pressure change can happen because of a storm, heat, cold, or using fuel. If there is vapor in the air, then the possibility of condensation is present. Time of year does not matter, however, in winter when the temperature can easily swing through 30 or 40 degrees in a day or two, there will be more air moving in and out of the tank. Being near a warm(ash) water source the air is always more humid than further inland.

By the time the Racor picks up the water in the tank, there will be a lot of water. Remember the pick up tube is not sitting on the bottom of the tank, it is just above it. Water has to reach the pick up tube in order to be sucked into the filter. When the tank begins to empty the return fuel line can stir up some water and other crud and suspend it in the fuel which will get picked up. That's how fuel polishing works.

The problem with any water in the tank is microbial action. The little bugs live at the interface of the fuel and water, the by products of their digestive system is acidic and gets trapped next to the aluminum tank. Aluminum and acid's don't mix well.

Unlike gasoline, diesel is a pretty stable fuel. Any degradation is unlikely to be noticed.

 

[jssailem]

Any degradation is unlikely to be noticed.

Certainly over 3-5 months. Over a couple of years... Maybe.

 

[sailme88]

Certainly over 3-5 months. Over a couple of years... Maybe.

WOW, is that the typical winter layup in the PNW (3-5 months)? We're already 2 months into ours and official winter is still 19 days away...
I go in relatively early ( first of May ) and feel blessed to get 5 months of sailing in...

 

[jssailem]

WOW, is that the typical winter layup in the PNW (3-5 months)?

I think you misunderstood my comment.
I quoted @dlochner and was speaking to the Poster @CarlN who is RI - Rhode Island. It is they who experience 3-5 months of lay-up.

In the PacificNW we leave our boats in the water, unless we are painting the bottom or doing some sort of work. If all is ok we even depart our marina and adventure our waters. We fill and use our fuel tanks.

Personally, my fuel has been clean since a positive program was implemented to filter and treat with biocides.
Last February we went on our Extreme 2019 Sailing Adventure. This year we are preparing for the 360 Vancouver Isle 2020 adventure. If I can sneak in a Feb or March cruise. We will be on the water.