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Propulsive Efficiency

This program calculates a simple estimation of the hydrodynamic/propulsive efficiency of a given ship. The larger the amount of water a hull displaces, the greater the power required to reach a certain speed. Also, when the design of the hull is not very efficient, a higher power will be required. The design of the hull and propellers can make a great difference in propulsive efficiency.

Dealing with a very heavy hull, the designers of the Japanese battleship Yamato paid close attention to these aspects, in order to achieve satisfactory prestations. In fact, the Yamato class was rather underpowered in comparison with foreign counterparts. But the design of the hull, fitted with a bulbous prow, was a masterpiece and allowed the "superbattleship" to reach a relatively high speed. On the other hand, the counterparts of the Iowa class relied in a very powerful propulsion plant and a rather narrow hull that allowed to reach the highest top speed for a battleship. The most modern warships, being considerably lighter, are comparatively very overpowered but their prestations are tied to a limit for reasons of economy. This means that modern warships do not take full advantage of the very increased propulsion power.

The following list, which includes two large ocean liners as well, values the performance that each ship achieved in relation to the available engine power. Having this one rather limited, older warships had to force their machinery to a high degree to achieve the intended top speeds. In the list this is indicated by higher numbers, whereas the most modern ships get much lower numbers because of their very superior engine power.

PHP application by Sakhalia Net Project

Displacement (tonnes - standard):
Power (shaft horse power):
Speed (knots - maximum):



Ironclad Caio Duilio (1876)
21.7
(11138 ton, 7710 hp, 15 kts)
Transatlantic Titanic (1911)
21.3
(52310 ton, 59000 hp, 24 kts)
Transatlantic Queen Mary (1934)
16.9
(81961 ton, 160000 hp, 33 kts)
Battleship Dreadnought (1906)
16.8
(18410 ton, 23000 hp, 21 kts)
Transatlantic Michelangelo (1962)
15.8
(45000 ton, 87000 hp, 30.5 kts)
Battleship Knyaz Suvorov (1902)
15.4
(13500 ton, 15800 hp, 18 kts)
Battleship Viribus Unitis (1911)
15.1
(20000 ton, 27000 hp, 20.4 kts)
Battleship Yamato (1940)
12.8
(71111 ton, 150000 hp, 27 kts)
Battleship Bayern (1915)
11.2
(28530 ton, 55967 hp, 22 kts)
Battleship Vittorio Veneto (1937)
9.7
(41376 ton, 128000 hp, 30 kts)
Battlecruiser Derfflinger (1913)
9.1
(26180 ton, 76634 hp, 26.5 kts)
Aircraft carrier Enterprise (1960)
8.9
(73858 ton, 280000 hp, 33.6 kts)
Battlecruiser Hood (1918)
8.9
(41125 ton, 144000 hp, 31 kts)
Battleship Queen Elizabeth (1913)
8.8
(27500 ton, 75000 hp, 24 kts)
Battleship Bismarck (1939)
8.3
(41700 ton, 150170 hp, 30 kts)
Transatlantic United States (1951)
7.2
(45400 ton, 240000 hp, 38.32 kts)
Battleship Iowa (1942)
7
(45000 ton, 212000 hp, 33 kts)
Antisubmarine Cruiser Kiev (1972)
7
(30530 ton, 140000 hp, 32 kts)
Battleship Richelieu (1939)
7
(35000 ton, 150000 hp, 30 kts)
Cruiser Long Beach (1959)
5.8
(15540 ton, 80000 hp, 30 kts)
Battlecruiser Kirov (1980)
5.6
(24300 ton, 140000 hp, 32 kts)
Aircraft carrier Hornet (1940)
5.6
(20000 ton, 120000 hp, 33.8 kts)
Cruiser Ticonderoga (1981)
3.9
(9500 ton, 80000 hp, 32.5 kts)