Japanese submarine Ro-33

The submarines of the K5 sub-class were versions of the preceding KT sub-class with greater surface speed.[1] They displaced 955 tonnes (940 long tons) surfaced and 1,219 tonnes (1,200 long tons) submerged. The submarines were 73 meters (239 ft 6 in) long, had a beam of 6.7 meters (22 ft 0 in) and a draft of 3.25 meters (10 ft 8 in). They had a diving depth of 75 meters (246 ft).[2]

For surface running, the boats were powered by two 1,450-brake-horsepower (1,081 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor. They could reach 19 knots (35 km/h; 22 mph) on the surface[3] and 8.25 knots (15.28 km/h; 9.49 mph) underwater. On the surface, the K5s had a range of 8,000 nautical miles (15,000 km; 9,200 mi) at 12 knots (22 km/h; 14 mph); submerged, they had a range of 90 nmi (170 km; 100 mi) at 3.5 knots (6.5 km/h; 4.0 mph).[1]

The boats were armed with four internal bow 53.3 cm (21.0 in) torpedo tubes and carried a total of ten torpedoes. They were also armed with a single 76.2 mm (3.00 in) L/40 anti-aircraft gun and one 13.2 mm (0.52 in) Type 93 anti-aircraft machinegun.[1]

Commissioned on October 7, 1935 the submarine saw action for Imperial Japanese forces during the Pacific Campaign of World War II. On 7 August 1942, Ro-33 sank the Australian motor vessel Mamutu in the Gulf of Papua near Murray Island, Torres Strait, with the loss of 114 lives. After shelling Mamutu until she was sinking, Ro-33's commander, Shigeshi Kuriyama, then ordered his gunners to open fire on the survivors, men women and children, as they struggled in the water. Of the full complement of passengers and crew, there were only 28 survivors.[4] The submarine was sunk near Port Moresby, Papua New Guinea with all hands (70 officers and men) by the Royal Australian Navy destroyer Arunta at 09°36′S 147°06′E on August 29, 1942.

• Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-962-6.
• Carpenter, Dorr B. & Polmar, Norman (1986). Submarines of the Imperial Japanese Navy 1904–1945. London: Conway Maritime Press. ISBN 0-85177-396-6.
• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Hackett, Bob; Kingsepp, Sander (2012). "IJN Submarine RO-33: Tabular Record of Movement". SENSUIKAN! Stories and Battle Histories of the IJN's Submarines. Combinedfleet.com. Retrieved 18 August 2015.
• Hackett, Bob; Sander Kingsepp (2003). "Kaichu Type". Sensuikan!. Combinedfleet.com. Retrieved 10 May 2009.
• Hashimoto, Mochitsura (1954). Sunk: The Story of the Japanese Submarine Fleet 1942 – 1945. Colegrave, E.H.M. (translator). London: Cassell and Company. ASIN B000QSM3L0.