The document discusses the relationships between a ship's speed, displacement, distance traveled, and fuel consumption. It states that daily fuel consumption varies as the cube of ship speed, as the 2/3 power of displacement, and as the square of speed multiplied by distance for a voyage. Examples are provided to demonstrate calculating new fuel consumption with changes in speed, displacement or distance. Specific fuel consumption is also defined as the fuel used per kilowatt hour of power.

1. NAVAL
ARCHITECTURE
FUELFUEL
CONSUMPTIONCONSUMPTION

2. AKD;Rev0;Feb02 SP-SMA 2
SPEED ANDSPEED AND
FUEL CONSUMPTIONFUEL CONSUMPTION
[Ref.1]

3. AKD;Rev0;Feb02 SP-SMA 3
SPEED ANDSPEED AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o At moderate speeds, the daily Fuel
Consumption in tonnes varies
approximately as the following:
(Ship Speed)3
o FC = k V3
where
1. FC = Daily fuel consumption in tonnes
2. V = Ship speed in knots
3. k = A constant

4. AKD;Rev0;Feb02 SP-SMA 4
SPEED ANDSPEED AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o FC = k V3
o So, from the above relation, old
and new fuel consumptions can
be written as the following:
3
3
..
..
old
new
V
V
nconsumptiodailyold
nconsumptiodailynew
=

5. AKD;Rev0;Feb02 SP-SMA 5
SPEED ANDSPEED AND
FUEL CONUMPTIONFUEL CONUMPTION
o Exercise:
oA ship burns 40 tonnes of fuel per
day at 12 knots, calculate her daily
fuel consumption at 11 knots
o(ANS: 30.8 tonnes per day)

6. AKD;Rev0;Feb02 SP-SMA 6
DISPLACEMENT ANDDISPLACEMENT AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o If displacement of a ship be altered
then fuel consumption per day in
tonnes will vary as the following:
(Displacement)2/3
o FC = k ∆2/3
where
1. FC = Daily fuel consumption in tonnes
2. ∆ = Ship’s displacement in tonnes
3. k = A constant

7. AKD;Rev0;Feb02 SP-SMA 7
DISPLACEMENT ANDDISPLACEMENT AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o FC = k ∆2/3
o So, from the above relation, old
and new fuel consumptions can
be written as the following:
3/2
3/2
..
..
old
new
nconsumptiodailyold
nconsumptiodailynew
∆
∆
=

8. AKD;Rev0;Feb02 SP-SMA 8
DISPLACEMENT ANDDISPLACEMENT AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o Exercise:
oA ship when displacing 16,000
tonnes burns 25 tonnes of fuel oil
per day at a certain speed,
calculate her daily consumption at
this same speed after discharging
3500 tonnes
o(ANS: 21.2 tonnes per day)

9. AKD;Rev0;Feb02 SP-SMA 9
DISTANCE ANDDISTANCE AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o The total fuel consumption in
tonnes for a passage/voyage varies
as the following:
(Ship Speed)2
x Distance
o TFC = k V2
x D where
1. TFC = Total fuel consumption in tonnes
2. V = Ship speed in knots
3. D = The cruising distance in nautical
miles
4. k = A constant

10. AKD;Rev0;Feb02 SP-SMA 10
DISTANCE ANDDISTANCE AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o TFC = k V2
x D
o So, from the above relation, old
and new fuel consumptions can
be written as the following:
oldold
newnew
xDV
xDV
nconsumptiototalold
nconsumptiototalnew
2
2
..
..
=

11. AKD;Rev0;Feb02 SP-SMA 11
DISTANCE ANDDISTANCE AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o Exercise:
oA ship burns 120 tonnes of fuel oil
on a passage of 2400 miles at 10
knots. At what speed can she
steam 3000 miles on 180 tonnes of
fuel oil
o(ANS: 10.95 knots)

12. AKD;Rev0;Feb02 SP-SMA 12
DISTANCE ANDDISTANCE AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o The total fuel consumption in
tonnes for a passage/voyage varies
as the following:
(Ship Speed)2
(For same distance)
o TFC = k V2
where
1. TFC = Total fuel consumption in tonnes
2. V = Ship speed in knots
3. k = A constant

13. AKD;Rev0;Feb02 SP-SMA 13
DISTANCE ANDDISTANCE AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o TFC = k V2
o So, from the above relation, old
and new fuel consumptions can
be written as the following:
2
2
..
..
old
new
V
V
nconsumptiototalold
nconsumptiototalnew
=

14. AKD;Rev0;Feb02 SP-SMA 14
DISTANCE ANDDISTANCE AND
FUEL CONSUMPTIONFUEL CONSUMPTION
o Exercise:
o On increasing the speed of a vessel by
1.5 knots it is found that the daily
consumption of fuel is increased by 25
tonnes and the percentage increase in
fuel consumption for a voyage of 2250
nautical miles is 20. Estimate (a) the
original daily fuel consumption and (b)
the original speed of the ship
o (ANS: 79.91 tonnes/day and 15.79 knots)

15. AKD;Rev0;Feb02 SP-SMA 15
SPECIFIC FUELSPECIFIC FUEL
CONSUMPTIONCONSUMPTION
o SFC is the fuel consumption per
kW per hour
o Normal SFC: 180 – 185 gm/kW/h
1000x1000
PowerxSFC
tonnesinnConsumptioFuelHourly =
1000x1000
24xPowerxSFC
tonnesinnConsumptioFuelDaily =

16. AKD;Rev0;Feb02 SP-SMA 16
BIBLIOGRAPHYBIBLIOGRAPHY
REFERENCESREFERENCES
1. E. A. Stokoe, Reed’s Naval Architecture for
Marine Engineers, 3rd
ed. (1973)
2. W. A. Fisher, Engineering for Nautical Students, 4th
ed. (1973)