"Roger Long" wrote in message
...
"Capt. JG" wrote

No... didn't miss it. He's dealing with bio/water issues every day. I
think I'll trust his experience, although he didn't say to be obsessive
about it. He's advocating exactly that... minimizing the surface area.

But he's missing out on the frequent opportunity to have the sloshing of a
partially full fuel tank knock off some bio film sticking to the sides.
He's also increasing the average age of the fuel with its absorbed water
content and oxidation. I've been working with commercial boat operators
for nearly four decades and never heard of trying to keep fuel tanks
topped up until this newsgroup.

Water absorption in diesel? Seems to me that would be a very, very small
issue, given that they don't mix. If the bio is stuck to the sides, why
would you want to knock it free? Better to kill it, filter the fuel and be
done. Do commercial boat operators let their boats sit for weeks at a time?
Seems to me that they would use their engines frequently, then fillerup,
then repeat. Thus, they are, in a sense, topping up, except the fuel is
lower when they start.

The yard manager I brought my non-running engine to when the boat arrived
in Portland had similar or more experience. He successfully diagnosed
that all it needed was a thorough cleaning after the Yamaha shop and
dealer in MI told me it needed two new injectors and possibly an injector
pump. The engine has been running perfectly for three seasons on those
components. That gives him a lot of street cred in my book. His position
on fuel was that you should use up as much as you can before refueling so
that most of what you are burning is as fresh as possible. Why do
experienced people differ on points like this? Because it doesn't make
much difference. Topping off might make sense for the once a month
weekender but would be crazy for the almost daily sailor such as myself
whether it was going to the fuel dock and standing in line, doing the
docking and undocking, etc., for a gallon or lugging a can all the way
down the dock at the end of the sailing day when tired guests want to get
home. The fuel sitting in that can is as likely to go bad as what is in
the tank. Do you keep topping up the can that you top up the tank with?
Where does it end?

Well, that's what I'm talking about... the once-a-month or slightly more
use. I've had the same diesel, less one topping off, for two years. I
haven't detected any difference in performance, so I don't think the
degradation issue is real (enough).

Ummm... my dock box is about 2 feet from my boat. I have a cart to move the
jug of fuel if I can't lift 3 gallons? Seems pretty easy.

What micron sizing do you use for the primary and secondary?

The Racor primary is 2 Mu because the polishing system keeps much crud
from every reaching it and it is oversized for the engine so there is no
downside to the finer element. It's pressure fed by the electric fuel
pump.

The secondary is a Yamaha engine mounted filter and probably 10 Mu. Since
only their elements fit, I have to buy whatever they supply for the engine
anyway.

The polishing filter is 10 Mu but, as Rich H points out, will take out
smaller stuff because the fuel goes through it many times and it is a
depth filter instead of a surface filter. It also gets finer as it loads
up.




--
"j" ganz @@
www.sailnow.com