Ha-7 class submarine

Japanese submarine Ha-7, in trials off Kure, 1916
Class overview
Builders:	Kure Naval Arsenal, Japan
Operators:	Imperial Japanese Navy
Preceded by:	Ha-3 class submarine
Succeeded by:	Kaichū type submarine
In commission:	1916–1929
Completed:	2
Retired:	2
General characteristics
Type:	Submarine
Displacement:	286 long tons (291 t) surfaced 321 long tons (326 t) submerged
Length:	43.3 m (142 ft)
Beam:	4.14 m (13.6 ft)
Draft:	3.43 m (11.3 ft)
Installed power:	600 hp (450 kW) (gasoline engines) 300 hp (220 kW) (electric motors)
Propulsion:	Gasoline engines Electric motors 1 shaft
Speed:	12 knots (22 km/h; 14 mph) surfaced 7 knots (13 km/h; 8.1 mph) submerged
Range:	660 nm @ 12 knots (surfaced) 60 nm @ 8.5 knots (submerged)
Test depth:	30.5 metres (100 ft)
Complement:	26 officers and enlisted
Armament:	4 × 18 in (460 mm) bow torpedo tubes (4 × torpedoes) 1 × machine gun

The Ha-7 class submarine (波七型潜水艦, Ha-nana-gata sensuikan) was an early class of submarines of the Imperial Japanese Navy. It was also called the "Vickers C-3 class".

A final two vessels of the British C class submarine design were built completely in Japan by the Kure Naval Arsenal as part of the emergency expansion of the Imperial Japanese Navy due to World War I. Although the design was considered obsolete by this time, these vessels were felt necessary to meet the perceived threat of German submarine activity in Japanese coastal waters. Physically almost identical to the Ha-3 class, the two vessels incorporated a number of improvements, including a change in the location of the rudder for better control, and the addition of two externally mounted torpedo tubes to double the attack capability from previous designs.

Arriving in Japan during the closing stages of the war, neither vessel was ever used in combat.