I.J.N.’s quest for an ocean-going submarine continued. In 1919 two boats of I.J.N.’s own design were completed at Kure Navy Yard. They were the first units of a long series of boats of KAICHU Type. KAICHU was the acronym of “Kaigun Chugata” (Admiralty medium type).

KAICHU TYPE 1 (Ro-11 Class)

This Type - KAICHU Type 1 - was heavily influenced by the French Schneider-Laubeuf boat. The two boats, designated as Boat #19 and #20 (later Ro-11 and Ro-12 respectively), were double-hulled, and were powered by powerful Sulzer diesels imported from Switzerland. They made 19 knots on the surface in the trial, which ranked them among the fastest boats in the world. Other features included two trainable deck-mounted torpedo tubes. But again their engines were plagued with troubles. In 1921 the two boats departed on the long-range cruise of some 3,000 miles for Formosa (Taiwan), but both of them failed on the way because of engine troubles.

Displacement 720/1,030 tons
Length 69.19 meters (227 feet)
Beam 6.35 meters (20’ 10”)
Draught 3.43 meters (11’ 3”)
Machinery twin-shaft diesel-electric
Power (diesel mfd. by Sulzer) 2,600hp
Power (electric) 1,200hp
Speed (diesel) 18.2 knots
Speed (electric) 9.1 knots
Fuel 60 tons
Radius of action (diesel) 4,000 miles @ 10 knots
Radius of action (electric) 85 miles @ 4 knots
Tubes (fwd) four 45cm (18 inch)
Tubes (deck) two (trainable) 45cm (18 inch) (carried ten torpedoes)
AA Guns single (retractable) 8cm
Depth of dive 30 meters (92 feet)
Crew 46

KAICHU TYPE 2 (Ro-13 Class)

Three more boats of improved Type - KAICHU Type 2 - were completed at Kure Navy Yard in 1920/21. But their mission design had to be formulated before the assessment of the previous Type had been completed. Therefore, the corrections contained in them were only half-measures. Those three boats designated as #23, #22 and #24 (later Ro-13, Ro-14 and Ro-15 respectively) had enlarged conning towers, shorter superstructures and fixed deck torpedo tubes. Apparently the trainable tubes of the previous Type were not successful. Like the previous Type, their seaworthiness still left much to be desired. The retractable AA armament of the previous model was changed to the fixed. The new Type carried ore fuel, extending the radius of operation by nearly 50% over the previous Type, but because of this, the surface speed decreased by 2 knots. This was by no means the satisfactory fleet-type boat desired by the I.J.N.

Displacement 740/1,003 tons
Length 70.10 meters (230 feet)
Beam 6.10 meters (20 feet)
Draught 3.68 meters (12’ 1”)
Machinery twin-shaft diesel/electric
Power (diesel mfd. by Sulzer) 2,600hp
Power (electric) 1,200hp
Speed (diesel) 16.5 knots
Speed (electric) 8.5 knots
Fuel 75 tons
Radius of action (diesel) 6,000 miles @ 10 knots
Radius of action (electric) 85 miles @ 4 knots
Tubes (fwd) four 45cm (18 inch)
Tubes (deck) two (fixed) 45cm (18 inch) (carried ten torpedoes)
AA Guns single (fixed) 8cm
Depth of dive 45.7 meters (139 feet)
Crew 46

KAICHU TYPE 3 (Ro-16 Class)

It seems that KAICHU Type 3 was more successful than the previous models, as the I.J.N. commissioned 10 units of this Type in 1920 through 1923. Their diesels were now manufactured locally under license, and the periscopes were also locally manufactured.

In addition to Kure Navy Yard and Kawasaki Dockyard Company (Kobe), which had been the sole manufacturers of submarines up to that time, now Yokosuka and Sasebo Navy Yards began to build submarines. But the performance of the boats of this type was mediocre at best. They had attained a degree of reliability, compared with their predecessors, but had not achieved the speed and seaworthiness the I.J.N. desired in a true ocean-going fleet-type submarine.

BOAT NUMBER	LATER DESIGNATION	YEAR OF COMPLETION
37	Ro-16	1922
34	Ro-17	1921
35	Ro-18	1921
36	Ro-19	1922
38	Ro-20	1922
39	Ro-21	1922
40	Ro-22	1922
41	Ro-23	1923
42	Ro-24	1920
43*	Ro-25	1921

* Boat #43 collided with the light cruiser TATSUTA off Sasebo harbor on 19 March, 1924 and was lost with all hands, but was raised and repaired.

Displacement 772/997 tons
Length 70.10 meters (230 feet)
Beam 6.12 meters (20’ 1”)
Draught 3.70 meters (12’ 1”)
Machinery twin-shaft diesel/electric
Power (diesel mfd. by Sulzer) 2,600hp
Power (electric) 1,200hp
Speed (diesel) 16.5 knots
Speed (electric) 8.5 knots
Fuel 75 tons
Radius of action (diesel) 6,000 miles @ 10 knots
Radius of action (electric) 85 miles @ 4 knots
Tubes (fwd) four 45cm (18 inch)
Tubes (deck) two 45cm (18 inch) (carried ten torpedoes)
AA Guns single 8cm
Depth of dive 45.7 meters (139 feet)
Crew 46 Other Axis Submarine Losses

14 June, 1940: MACALLE was wrecked on a reef in the Red Sea at 19.00N x 38.00E;

17 June, 1940: PROVANA was sunk by the French LA CURIEUSE off Oran;

19 June, 1940: GALILEO GALILEI under CC Nardi, was captured by HMS MOONSTONE at 12.48N x 45.12E a few days after her only success, the sinking of the Norwegian tanker JAMES STOVE;

20 June, 1940: DIAMANTE was sunk by HM Submarine PARTHIAN at 32.42N x 23.40E

22 June, 1940: EVANGELISTA TORRICELLI under C.C. Pelosi was sunk by the ROYAL NAVY destroyers HMS KANDAHAR, HMS KINGSTON HMS KHARTOUM and the sloops HMS SHOREHAM and HMS INDUS at 12.34N x 43.16E. There was a forty minute gun battle during which time TORRICELLI got off a four-torpedo spread which the ROYAL NAVY ships evaded, but a single 10cm round from TORRICELLI hit HMS SHOREHAM, causing minor damage however another 10cm round hit HMS KHARTOUM and the splinters detonated one of the DD’s own torpedoes aboard, which burned and destroyed that ship.

More History of the Japanese Submarine Navy

Part 1: 1905
Part 2: 1912-17
Part 3: C-1 and C-2
Part 4: Ha-9, Ha-10 and Tsing-Tao
Part 5: Ro-11, Ro-13, Ro-16
Part 6: Ro-1, Ro-3
Part 7: Kaichu Type 4
Part 8: Batteries
Part 9: Ro-57 and Ro-60
Part 10: I-16
Part 11: O-1 (ex U-125) and O-2 (ex U-46)