Fuel System and Fuel Measurement - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 73

atmosphere

inlet

HC

feed back
flow

vant

surge drum

alarm

outlet

counter

Fig. 4.11 Tank with hydrocarbon control equipment

The ship must be equipped with fuel to cover its power requirement. The
necessary quantity must be determined before the start of a journey by route
planning based on the relations of:

B ¼ b P S
v

¼ b P t ð 4 : 2 Þ

.

In this equation the parameters are:

• B the fuel needed for the journey in kg or in lb;
• b the Specific Fuel Consumption of the engine in kg kWh -1

or in oz BTU -1 ;

• P the propulsion performance in kW or in BTU s -1 ;
• S the journey distance in nmi, mi ,or km, including drift due to wind in atmo-
sphere and currents in water;
• v the speed of the ship in nmi h -1 ,inkmh -1

or in mph; and

• t the time of the journey in h [ 58 ].

The necessary information can be obtained from the fuel management docu-
mentation [ 59 ]. Figure 4.12 shows an example of the required fuel quantity as a
function of the ship's velocity.
Fuel management provides optimal solutions to reduce fuel consumption.
Merchant vessels, such as container ships, drive at a reduced speed to save fuel
since the reduction of the speed from 25 to 20 knots, i.e., 46.3-37.04 km h -1
lowers consumption by about 20-25% [ 60 ]. Bulk carriers often deliver perishable
goods; therefore, reducing the speed is not possible. Tankers can usually reduce
speed without encountering any delivery problems. The fastest civil ships are high