Worked Examples

Parameter	Unit	HMS Hermes	HMS Ark Royal	USS Midway	USS Nimitz
Length	metres	209	219	275	312
Displacement	tonnes	29000	54300	63125	90000
Power	SHP	76000	152000	212000	280000
Speed	knots	28	31.5	33	33
Speed	m/s	14.4	16.2	16.98	16.98
Wetted Area	sq metres	6352	8897	10750	13671
Frictional Resistance	kNewtons	1156	2002	2619	3326
Power to overcome Frictional	SHP	27900	54400	74500	94700
Power to overcome Residual	SHP	48100	97600	137500	185300
Power per tonne Frictional	SHP/Tonne	0.96	1.0	1.2	1.0
Power per tonne Residual	SHP/Tonne	1.7	1.8	2.2	2.1
Power per tonne Total	SHP/Tonne	2.6	2.8	3.4	3.1

The above worked examples attempt to show the power/weight ratios required to overcome frictional and residual resistance (wave-making + eddy-making + air) of the various Aircraft Carriers at each one's top speed. As we do not know the conditions required for the given speeds we must approximate.

Data is extracted from Janes Fighting ships - and is subject to the usual errors inherent to that publication.

Conclusions that can be drawn is that the power per tonne ratio, at the given speeds and taking into account the differing lengths seems fairly reasonable. We can, with some degree of confidence, conclude that our earlier workings seem to be reasonable. These figures support the earlier conclusions quite closely.

Back to Carriers.