Type B1 submarine

I-26
Class overview
Name	B1 class
Operators	Imperial Japanese Navy
Preceded by	Type J3 submarine
Succeeded by	Type B2 submarine
Completed	18
Lost	17
Scrapped	1
General characteristics
Class and type	Cruiser submarine
Displacement	2,631 tonnes (2,589 long tons) surfaced 3,713 tonnes (3,654 long tons) submerged
Length	108.7 m (356 ft 8 in) overall
Beam	9.3 m (30 ft 6 in)
Draft	5.1 m (16 ft 9 in)
Installed power	12,400 bhp (9,200 kW) (diesel) 2,000 hp (1,500 kW) (electric motor)
Propulsion	Diesel-electric 2 × diesel engine 1 × electric motor
Speed	23.5 knots (43.5 km/h; 27.0 mph) surfaced 8 knots (15 km/h; 9.2 mph) submerged
Range	14,000 nmi (26,000 km; 16,000 mi) at 16 knots (30 km/h; 18 mph) surfaced 96 nmi (178 km; 110 mi) at 3 knots (5.6 km/h; 3.5 mph) submerged
Test depth	100 m (330 ft)
Crew	94
Armament	6 × bow 533 mm (21 in) torpedo tubes 1 × 14 cm (5.5 in) deck gun 2 × single 25 mm (1 in) Type 96 anti-aircraft guns
Aircraft carried	1 × floatplane
Aviation facilities	1 × catapult

The Type B1 submarine (巡潜乙型潜水艦, Junsen Otsu-gata sensuikan, lit. "Cruiser submarine type B"), also called I-15-class submarine (伊一五型潜水艦, I-jū-go-gata sensuikan) was the first group of boats of the Type B cruiser submarines built for the Imperial Japanese Navy (IJN) during the 1940s. In total 20 were built, starting with I-15, which gave the series their alternative name.