Fleet submarine


A fleet submarine is a submarine with the speed, range, and endurance to operate as part of a navy's battle fleet. Examples of fleet submarines are the British First World War era K class and the American World War II era Gato class.
Within the modern Royal Navy, the term is used for the British nuclear-powered attack submarines. In the United States Navy, the term came to be used primarily for the long-range submarines that served in World War II.

Examples

United States

The term was used by the United States Navy to distinguish submarines suitable for long range patrols in the Pacific Ocean from earlier classes such as the United States S-class submarines. The initial goal, pursued with frequent interruptions since the AA-1-class launched 1918-19, was to produce a submarine with a surfaced speed of 21 knots to operate with the Standard-type battleships of the surface fleet. Most of the nine "V-boats" launched 1924-33 were either attempts to produce a fleet submarine or were long-range submarine cruisers. Eventually, a long range of was combined with high speed, beginning with the Salmon-class launched in 1938, to allow sustained operations in Japanese home waters while based at Pearl Harbor. These qualities also proved important in the Pacific commerce raiding of World War II, but the 1922 Washington Naval Treaty's prohibition on unrestricted submarine warfare precluded inter-war planning in this area. Although the Gato-class was considered the fully developed archetype, the earlier Porpoise, Salmon, Sargo and Tambor-classes were incrementally improved prototypes distinctly different from the two contemporary experimental Mackerel-class coastal submarines. The Tambors were fully developed and similar to the Gatos except for diving depth and separation of the engines into two compartments.

Japanese

Japanese I-boats were a conceptually similar long-range differentiation from smaller "medium" or "sea-going" Ro-boats, although some I-boats had features like aircraft hangars and large-caliber deck guns more often associated with submarine cruisers.

British

In order to get the speeds - over 20 knots while surfaced - required to match their capital ships and to be able to screen ahead of the fleet or flank the enemy, the British initially used steam propulsion. The K-class entering service in 1916 were large for their time. Although able to reach 24 knots the complexity of shutting down boilers and stowing funnels made them slow to dive.
As the speed of capital ships increased, the United Kingdom abandoned the fleet submarine concept following completion of three 21-knot River-class submarine submarines of the early 1930s using supercharged diesels, because the size required for range and surface speed decreased maneuverability.

Others

Continental European nations sometimes used the terms "ocean-going", "long-patrol", "type 1" or "1st class" submarines, generally referring to Atlantic or Indian Ocean operations in the absence of anticipated need for Pacific patrols, and often without the speed for fleet operations.

Comparison of World War II submarines

NameTypeNationSurface DisplacementSubmerged DisplacementSpeedTorpedo TubesCrewReference
fleet submarineUnited States1,525 tons2,415 tons20 kt1080
fleet submarineUnited Kingdom1,850 tons2,723 tons22 kt861
fleet submarineJapan1,833 tons2,602 tons23 kt680
Type IXD2ocean-going submarineGermany1,616 tons1,804 tons19 kt657
Redoutable-classocean-going submarineFrance1,570 tons2,084 tons17 kt961
Kaichū typemedium submarineJapan1,115 tons1,447 tons19 kt480
Type XBminelayerGermany1,763 tons2,177 tons16 kt252
submarine cruiserItaly1,461 tons2,136 tons18 kt1485
Type B1submarine cruiserJapan2,584 tons3,654 tons23 kt6100
O 21-classmedium submarineNetherlands888 tons1,186 tons19 kt855
Type VIICmedium submarineGermany769 tons871 tons17 kt544
minelayerItaly1,371 tons1,883 tons15 kt666
600 seriesmedium submarineItaly615 tons855 tons14 kt641
S-classmedium submarineUnited Kingdom715 tons990 tons14 kt644
minelayerUnited Kingdom1,520 tons2,157 tons15 kt659
medium submarineFrance662 tons856 tons14 kt941
Narwhal-classsubmarine cruiserUnited States2,730 tons4,050 tons17 kt690
Surcoufsubmarine cruiserFrance3,250 tons4,304 tons18 kt12118
minelayerUnited States2,710 tons4,080 tons15 kt489
S-boatsmedium submarineUnited States840 tons1,150 tons15 kt442