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From: Arild Jensen (no email)
Date: Wed Sep 03 2003 - 17:59:02 EDT
Ronald Barr wrote:
I think the reason we don't hear much on this list about Flow Scan on this
list is because of the $$$$ they cost and the possibility that perhaps most
trawler fuel consumption per hour is fairly low.
It isn't just the initial outlay of about $1000 per engine for Flow Scan it is
also the installation cost. <<< snip>>>
Anyone with any input who use Flow Scans I would love to hear about it. I have
looked at them
Ron Barr
REPLY
This is an area I have given some thought to.
For boats with a small day tank, the problem of measuring fuel consumption
can be simplified by only burning fuel from this small calibrated day tank.
A transfer pump combined with a flow totalizer ( much less expensive than flow
scan) will log how much fuel is transferred into the day tank.
The return flow from the pump/injector is always returned to the day tank.
In this way you only have to track the amount transferred into the day tank.
For situations where you have a partial quantity remaining in the day tank
after a particular run, a dip stick or other means can be used to measure
quantity remaining. This is now deducted from the number of tank fuls used
during the measured run.
For convenience the day tank should have a regular shape to facilitate dip
stick measurements with greater accuracy.
Sight glasses can also be used.
For example a 12 gal day tank can accommodate three hours plus of 3 Gal / hour
consumption including a safety reserve.
In addition the specific consumption curve of a given engine as a function of
RPM is also useful.
This enables you to create a table of values for the normal range of
operating speeds you use in normal cruising.
Most trawlers rarely run slower than 3 knots ( trolling for fish ) or faster
than a comfortable hull speed.
If you want to get really exact, it might be possible to use one of those
variable hour meters Maurin mentioned was used in piston aircraft.
Why bother you ask?
Well this system is cheaper than a Flow Scan. Simpler in plumbing and less
complicated to install.
In addition it can often be implemented by using existing fuel tanks and
transfer/ polishing pumps.
Best of all, the logging record is available in any dollar store as a notepad
and pencil. Just record how often you refill the day tank.
And the record is impervious to power failures. < grin>
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