Printed 7/2/2016
MV Lioness Owners Notes v2015.2
Page 26 of 36
Fuel Management
Checking level
1.
Use aft starboard and aft port fuel tanks only.
2.
Locate the sight tube for the desired tank.
3.
Open the top and bottom valves on the desired sight tube.
4.
Read the level of the tank.
5.
Shut off the sight tube valves on the top and bottom. (For safety never
leave valves open.)
Fuel Manifold
The fuel system for diesel engines may appear complicated but is usually
very simple. Diesel engines have fuel pumps which deliver the same
amount of fuel no matter how fast they are running. More fuel is delivered
to the engines than can possibly be used even at wide open throttle so
excess fuel must be returned to the fuel tank. When the engine is running
slowly more fuel is returned because less is burned than at faster speeds.
On a long range trawler like Lioness multiple tanks are needed to increase
the capacity because it is usually not possible to place very large tanks on
board. Fuel tends to slosh around in large fuel tanks even when baffles are
added during construction. A benefit of multiple tanks is the ability to
transfer fuel for weight distribution. A second benefit is the ability to
“polish” the fuel in one pass by drawing from one tank and returning to
another. The fuel passes through the Racor filter and is cleaned (or
polished) of contaminants. The general rule of thumb is that fuel requires
six passes through a filter if it is returned to the same tank. Neither fuel
transfer or polishing should be operated by charterers.
On Lioness, fuel is drawn from one tank and returned to the same tank.
The exceptions would be when transferring fuel. With both engines running
at approximately 2,000 rpm approximately 25 gallons per hour (GPH) is
drawn from the tank and approximately 19 GPH is returned. The reason to
draw and return from only one tank is that if more than one valve is open, a
tank could be filled to overflowing out the vent. As the boat starts to list,
fuel will be transferred in the direction the boat is listing accelerating the
problem.
The fuel system on Lioness consists of a “Return” manifold and a “Feed”
manifold. Located on the forward engine bulkhead, the upper manifold is
the “Return” manifold and the lower manifold is the “Feed”. For running,
both engine and generator feed lines are left in the open position (lever in
line with copper line). Note: the engine and generator return lines do not
