"Roger Long" wrote in message
...
"Capt. JG" wrote
This is exactly what the guy with 30+ years of experience said on
Saturday. It was recommended to add a dual (filter)....
So you are going to add that second filter ARE you not? In view of the
high current conditions in SF Bay and your responsibility to your students
I'd hate to be you if something happened due to fuel contamination after
posting that you were aware of this recommendation.
I probably will. I need to haul out in the next couple of months, and given
"fandamily" stuff coming up... Turkey/Xmas, I probably won't be teaching on
her until after the haul.
The thing is... I don't really use the engine all that much during much of a
class. I'm pretty careful about doing all the preliminary checks, which are
part of the typical class. The basic class I teach has the first 1/2 day +
as engine awareness/use, and for that we're typically in and around a
marina. The only time the engine has quit unexpectedly was when a student
throttled back so much that the engine died... throttle is the kill switch
for my boat. This actually happend during the last class when we were
practicing motoring up to and stopping at a mooring. Engine quit, no
problem. I popped the jib and we sailed off in two seconds flat.
While you are at it, consider this:
I think my system has gotten a bad rap for complexity due to the dual
tanks which does drive up the cost and complexity a lot. Here is what it
would look like in yours or the typical single tank boat:
http://home.maine.rr.com/rlma/1tankFOsystem.gif
The Shelco Filter was about the same cost as a Racor. The second pump was
about 60 bucks and is also a good redundancy feature. This redundancy
would be especially desirable in a boat with a low mounted tank that will
not gravity feed. Otherwise, there are only one or two additional valves
and a few fittings more than in the dual filter system. The cost
difference is insignificant in boat bucks.
Fuel contamination and degradation is always going on to some extent.
This system is constantly removing it whenever the engine is running. The
system will filter a volume equal to the typical sailboat tank every hour
of running time. Your dual filter OTOH is just sitting there doing
nothing useful.
Fuel flow at the tank inlet is vastly greater than in the typical system.
This increases the uptake of water and anything else floating around in
the bottom of the tank waiting for rough water and a tight spot to get
sucked into the system at the worst possible time. Since most of the fuel
is going through the polishing filter and being returned to the tank,
getting this stuff into the fuel system is a good thing.
True, but in the SF bay, "rough" sailing (bouncing around) is pretty
typical. Always looking for the zephyr, but... well, it happens, hopefully
around lunch time. LOL
In the event of the primary filter (Racor on the drawing) loading up, OR
the primary fuel pump failing, just turn one valve and you are back in
business with full fuel flow. Some tank configurations or engine driven
fuel pump problems may require partially or completely closing the second
valve. In any event, it doesn't take any longer than switching filters.
Let's say you do pick up a load of bad fuel and calling a fuel polishing
contractor isn't an option either because you are cruising or there isn't
one as is now the case here in Portland. (BTW, none of this has anything
to do with an old and neglected tank that has gotten thouroughly coated
and filled with slime. That's a different issue all together.)
Geez... I hope not around here. The big issue is whether or not the fuel
pump attendant is around so I can pay him. Early in the summer, he wasn't...
pumps were unlocked and there were two of us standing around for a while to
see if he would return. Finally, we just left the cash in the office (also
unlocked).
Last I pulled the single filter from the primary, I almost didn't replace it
because it looked so good...
Duel Filter Setup:
Switch filter.
Change first filter element - 16 bucks.
Run for a while.
Repeat as often as necessary at about 16 bucks a filter element.
The only way to get fuel flow is to run the engine That means doing these
repeated and expensive filter changes underway or with the engine running
at the dock and sucking very little fuel. With an engine the size you
have on your boat, it will take 20 - 30 hours to run all the fuel through
the filters. And, you have to consume it which adds to the expense.
Polishing Setup:
Turn red valve and isolation valve if necessary and deal with it when you
get back to the dock. The high capacity of the Shelco makes its load up
time much higher than the Racor or similary filter. You can change it's
two buck element while the engine runs on the Racor, just as on a dual
filter system if it does load up.
When you get back to the dock, you can plug into shore power and let the
polishing system run with the engine off, changing two dollar filter
elements as necessary.
Based on the amount of crud I found in my Shelco and the pristine
condition of the sediment bowl in my Racor, I would say loading up of the
Racor is unlikely in any event.
Here's a challenge. Usually after you've taken a seminar like the one you
just did, they will entertain a few follow up questions. Take this
schematic to your guy and let us know what he thinks.
I'll see what I can do. I copied out the schematic and I'll email it to him,
along with your explanation.
--
"j" ganz @@
www.sailnow.com