On Nov 17, 1:10*pm, "Roger Long" wrote:
"Two meter troll" wrote

Roger, why not double the filters and install a two position Y valve
them so you can shut off the clogged filter and run through a new
instead of trying to change out while running?

Did you read the post? *The boat will run on the Shelco filter and polishing
pump until that filter loads up which will take a lot, lot, longer than a
second Racor to become non-functional.

Or, do you mean having 4 filters?

--
Roger Long

four filters. two sets paired with a y valve so you can run through
one or the other in the set. it would save you changing out filters in
bad weather (which IME is when filters clog up) or while running.

Two meter troll wrote:

four filters. two sets paired with a y valve so you can run through
one or the other in the set. it would save you changing out filters in
bad weather (which IME is when filters clog up) or while running.

That would certainly increase redundancy but, so would a third set of
filters. It has to end somewhere on a 32 foot boat.

The reason filters clog up in bad weather is because the motion of the boat
stirs up the stuff that's been sitting in the bottom of the tank. The whole
point of the polishing system is to remove that stuff before you get into
bad weather. Before bad weather or going into a spot where power is vital,
it would be good to take a peek at the filter gauges to see if they show any
restriction. This would be an especially good thing to do with a new load
of fuel.

With the high capacity of the Shelco filter, it's pretty unlikely I'll be
changing elements underway.

--
Roger Long

On Nov 19, 3:28*pm, "Roger Long" wrote:
Two meter troll wrote:
four filters. two sets paired with a y valve so you can run through
one or the other in the set. it would save you changing out filters in
bad weather (which IME is when filters clog up) or while running.

That would certainly increase redundancy but, so would a third set of
filters. It has to end somewhere on a 32 foot boat.

The reason filters clog up in bad weather is because the motion of the boat
stirs up the stuff that's been sitting in the bottom of the tank. *The whole
point of the polishing system is to remove that stuff before you get into
bad weather. *Before bad weather or going into a spot where power is vital,
it would be good to take a peek at the filter gauges to see if they show any
restriction. *This would be an especially good thing to do with a new load
of fuel.

With the high capacity of the Shelco filter, it's pretty unlikely I'll be
changing elements underway.

--
Roger Long
IME the fuel polishing only works for stuff suspendid in normal
conditions; I have never seen a tank that didnt have stuff in the
bottom that only got into the filters in really bad conditions.
As you say. Me I like redundancy when I can get it.

Two meter troll wrote:

IME the fuel polishing only works for stuff suspendid in normal
conditions; I have never seen a tank that didnt have stuff in the
bottom that only got into the filters in really bad conditions.
As you say. Me I like redundancy when I can get it.

You have to remember that the polishing pump is drawing at 20 - 30 times the
rate of the normal fuel pump. That makes it much more effective at sucking
stuff up out of the bottom of the tank. With my retrofitted system, both
engine and polishing flow are drawn through the same suction. I actually
can't draw a tank quite as low with the polishing system running as I can
with just the engine drawing because it sucks air down about an inch and
into the intake.

--
Roger Long

On Nov 19, 7:28*pm, "Roger Long" wrote:
Two meter troll wrote:
IME the fuel polishing only works for stuff suspendid in normal
conditions; I have never seen a tank that didnt have stuff in the
bottom that only got into the filters in really bad conditions.
As you say. Me I like redundancy when I can get it.

You have to remember that the polishing pump is drawing at 20 - 30 times the
rate of the normal fuel pump. *That makes it much more effective at sucking
stuff up out of the bottom of the tank. *With my retrofitted system, both
engine and polishing flow are drawn through the same suction. *I actually
can't draw a tank quite as low with the polishing system running as I can
with just the engine drawing because it sucks air down about an inch and
into the intake.

--
Roger Long

Roger I do understand that and i work in an industry where fuel
polishing is SOP because we are out in it all the time. i made the
suggestion because the redundancy to me is paramount and i never ever
trust one system when i can have a backup. I am in no way knocking
your system

On Wed, 19 Nov 2008 13:18:54 -0800 (PST), Two meter troll
wrote:

four filters. two sets paired with a y valve so you can run through
one or the other in the set. it would save you changing out filters in
bad weather (which IME is when filters clog up) or while running.

Since he has a single engine usually two switchable filters would
suffice.

On Nov 19, 8:37*pm, Wayne.B wrote:
On Wed, 19 Nov 2008 13:18:54 -0800 (PST), Two meter troll

wrote:
four filters. two sets paired with a y valve so you can run through
one or the other in the set. it would save you changing out filters in
bad weather (which IME is when filters clog up) or while running.

Since he has a single engine usually two switchable filters would
suffice.

his fuel polishing system disallows this if he wants a proper fuel
line pressure in all cases. his decision, his boat. pointing out
options was my idea.

Two meter troll wrote:

his fuel polishing system disallows this if he wants a proper fuel
line pressure in all cases. his decision, his boat. pointing out
options was my idea.

I appreciate the suggestions. However, for sake of discussion and anyone
looking at it for ideas on their sailboat:

(Schematic of my system he
http://home.roadrunner.com/~rlma/StriderFuelSystem.htm)

My system is a very tolerant, low pressure system. It runs from the main
tank quite well with gravity feed alone up to the mechanical fuel pump. The
mechanical fuel pump draws quite well from the low tank with the electric
fuel pump turned off but the vacuum is higher than I would like to subject
the pump to for long periods.

The pressure head at the mechanical pump inlet is the same when running off
the bypass as it is when gravity feeding from the main tank. If this should
be insufficient due to the secondary engine mounted filter starting to load
up or a fault in the mechanical fuel pump, I can gradually close the
isolation valve to force fuel to the engine at up to the full pressure that
the polishing pump can develop. This pump BTW does not have the pressure
cut off and regulation feature of a normal FO lift pump.

In a single tank installation with a bilge tank significantly below the
engines and fuel system, there might not be sufficient fuel pressure and
partial closing of the isolation valve might be necessary. In my case
though, I get normal fuel line pressure in all cases as well as the option
of increasing it.

It's worth repeating Rich H's brilliant idea for further redundancy:

The fuel polishing line runs to a small gravity feed tank that contains 1 -
2 hours of fuel. The line goes in the bottom of the tank from the polishing
system and exits the top on its way back to the main tank. A line runs from
this tank directly to the engine bypassing the engine driven fuel pump and
the vent has a valve on it. The fuel line could also bypass the engine
mounted fuel pump in some installations but not on mine since the injector
return line goes back to the filter instead of the tank, a Yanmar oddity.
This tank is constantly being filled, flushed, and renewed with just
filtered fuel that doesn't sit in the tank when the engine is running. If
all else fails, just open the supply and valves and a supply of clean fuel
sufficient to get the vessel out of trouble or change filters goes directly
to the engine.

In any event, I can change filters alternately on my system until I run out
of elements so I'm pretty well covered for the worst case situation. I've
also got those sails

--
Roger Long