[C320-list] Fuel tank not full

[Brian McLamb]

Not sure where your vessel is located so it is hard to recommend a
universal solution.  I am in NC not far from Beaufort and the winter is
usually not freezing for an extended period.  Swings above and below
freezing occur regularly throughout the winter months.  In the 11 years of
keeping my boat in the water all year through various temperatures, just
keeping the fuel tank full has not been a problem.  The continuous use of a
biocide has worked well without any water absorption additive.

Brian McLamb, s/v Serenity #1075


On Sun, Nov 19, 2017 at 9:17 AM Graeme Clark <cg at skyflyer.co.uk> wrote:

> Troy
> Great to hear some common sense on this recurring issue!
> Continuing with your calculations I think that means a *maximum* of 1/2 oz
> of water from an empty fuel tank
> I believe the Racor filter unit is designed also to extract water?
> When the tank is full it will gravity feed (siphon) to the filter so if
> concerned, an owner could - at the beginning of the next season - siphon
> off a bit of “fuel” to ensure no water is there
> Graeme
>
>
> Sent from mobile: please excuse typos etc.!
>
>
> > On 19 Nov 2017, at 09:04, Troy Dunn <troutwarrior at gmail.com> wrote:
> >
> > David-
> >
> > Not sure why no one has responded.  As I'm sure you know the conventional
> > wisdom is that leaving the tank partially filled with a hygroscopic fluid
> > like Diesel fuel in the tank leaving room for condensation you may end up
> > with water in your fuel, only IF there is in fact condensation, and then
> > the condensation is subsequently drawn into the Diesel.  Mainesail did a
> > fairly extensive experiment with an empty tank (
> > http://www.pbase.com/mainecruising/fuel_tankt_condensation ) but others
> > would point out that without a hygroscopic fluid in the tank,
> perhaps...the
> > accumulated moisture was just evaporating once the humidity dropped
> again.
> >  I have not seen a more controlled and well documented experiment, than
> > Mainesail's.
> >
> > My opinion is that as long  as your deck plate isn't leaking water into
> the
> > tank, and you put some sort of fuel conditioner in your tank for the
> winter
> > along with a biocide...you should be fine.    You could always run an
> > experiment and let us know your results.   Draw off a pint of fuel every
> > month from your Racor filter and see if you get any water in the fuel.
> > The water in your fuel tank will sink to the bottom, so it should be the
> > first thing that is drawn into the Racor each time you do the experiment.
> > You could also check the Racor before draining to see if any water has
> > settled there but I think you need to keep drawing off the fuel to get to
> > what's in the bottom of the tank.
> >
> > At the end of your winter, my prediction is that you will find no water
> in
> > the fuel.   It's a total guess, but I'm thinking that generally in most
> > areas, winters are dry not humid and without high humidity in the air and
> > without the fuel in the tank warming sufficiently for the tank to
> > breathe...condensation will be minimal.   Keep in mind that a 20'x20'x10'
> > room (4,000 cubic feet) at 100% humidity has roughly 1/2 gallon of water
> > content.   You'd need a LOT of air exchange and high humidity to get to
> > that much water.
> >
> > On the flip side...if you can't sleep at night, by a diesel fuel can,
> fill
> > it at your local gas station and top of your tank.
> >
> > Fair Winds-
> >
> > Troy Dunn
> > S/V Wonky Dog
> > Hull#514
> >
> >> On Fri, Nov 17, 2017 at 3:34 PM, David Nolte <dcnolte at mac.com> wrote:
> >>
> >> I always top off my fuel tank heading into the winter. So when we went
> to
> >> do our final pump out our marina had run out of diesel fuel. My 20
> gallon
> >> tank is 3/4 full. Should I worry about condensation and getting water in
> >> the tank? Has anyone had negative consequences in a similar situation?
> >>
> >> Thanks!
> >>
> >> David Nolte
> >> Beach House 0004
>
> --
Brian McLamb