Jingei-class submarine tender

Jingei (above) and Chōgei in 1924
Class overview
Name:	Jingei-class submarine tender
Builders:	Mitsubishi Heavy Industries
Operators:	Imperial Japanese Navy
Cost:	2,900,000 JPY
Built:	1922 – 1924
In commission:	1923 – 1945
Planned:	2
Completed:	2
Lost:	1
Retired:	1
General characteristics (initial)
Displacement:	5,160 long tons (5,243 t) standard 7,678 long tons (7,801 t) trial
Length:	125.40 m (411 ft 5 in) overall 123.00 m (403 ft 7 in) waterline
Beam:	16.22 m (53 ft 3 in)
Draught:	6.28 m (20 ft 7 in)
Propulsion:	2 × Parsons geared turbines 2 shafts, 7,500 shp Jingei 6 × Kampon coal/oil-fired boilers Chōgei 5 × Kampon coal/oil-fired boilers
Speed:	18.5 knots (21.3 mph; 34.3 km/h)
Range:	10,400 nmi (19,300 km) at 14 kn (16 mph; 26 km/h)
Capacity:	1,900 tons oil 27 × torpedoes 3 × periscopes
Complement:	Jingei: 364 Chōgei: 399
Armament:	Jingei, 1923 4 × 140 mm (5.5 in) L/50 naval guns 2 × 76.2 mm (3.00 in) L/40 AA guns 2 × 7.7 mm machine guns
Aircraft carried:	1927-1942 1 × float plane
Aviation facilities:	derrick and deck
General characteristics (and after 1935)
Displacement:	6,240 long tons (6,340 t) standard 8,288 long tons (8,421 t) trial
Length:	123.47 m (405 ft 1 in) waterline
Beam:	17.15 m (56 ft 3 in)
Draught:	6.60 m (21 ft 8 in)
Speed:	16.0 knots (18.4 mph; 29.6 km/h)
Armament:	Jingei, 1944 4 × 140 mm L/50 naval guns 2 × 76.2 mm L/40 AA guns 2 × Type 96 25 mm AA guns 4 × Type 93 13 mm AA guns 1 × 21-Gō early warning radar Chōgei, 1945 4 × 140 mm L/50 naval guns 2 × 76.2 mm L/40 AA guns 14 × Type 96 25 mm AA guns 4 × Type 93 13 mm AA guns 1 × 21-Gō early warning radar

The Jingei-class submarine tenders (迅鯨型潜水母艦,, Jingei-gata Sensuibokan^?) were a class of submarine tenders of the Imperial Japanese Navy (IJN), and served from the 1920s through World War II. Two vessels of this class were built between 1922 and 1924 under the Eight-eight fleet plan.

The IJN planned to build over 100 submarines under the Eight-eight fleet plan, and it was recognized that support ships would be needed. The Jingei class was planned specifically for this purpose. The duties of a submarine tender included serving as a flagship for the Submarine Division Commander and as a depot ship for the nine Kaichū-type submarines in a division.

At first, the Jingei class was planned as a 14,500 ton submarine tender. However, the specifications were revised to 8,500 tons (standing) class, as stipulated by the Washington Naval Treaty. This treaty would turn out to have a great impact on the Japanese shipbuilding industry. The IJN had intended to develop a large naval fleet, but under the treaty stipulations, the size of the intended fleet had to be greatly reduced. As a result, many shipbuilding companies incurred financial difficulty.

The IJN contracted the design details and construction of the Jingei to Mitsubishi. Naval contracts were directed toward Mitsubishi to prevent it from suffering the financial difficulty that had befallen other companies. The IJN handed only the required specifications to Mitsubishi, allowing for a greater freedom of design. The IJN recycled eight Tosa-class coal/oil-fired boilers for the development of the Jingei class of ships. Mitsubishi engineers worked on the design until the displacement of the Jingei was reduced to 8000 tons in the basic plan. However, the maximum speed was increased by 2.5 knots.

When Mitsubishi designers went to work developing the Katori-class cruiser, they implemented many design innovations that had been developed during their work on the Jingei. As a result, the Katori-class cruisers came to resemble the Jingei-class submarine tenders.