[C320-list] Fuel tank not full

[Graeme Clark]

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