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  RO-33 Japanese Submarine
Kaichu Type submarine

1,109 Tons (surfaced)
264' x 23' x 13'
4 x forward torpedo tubes
10 Long Lance torpedoes
1 x 80mm gun
2 x 25mm guns

Click For Enlargement
IJN 1942
Ship History
Built at the Kure Navy Yard in Kure. Completed October 7, 1935. Commissioned into the Maizuru Naval District. Assigned to SubRon 4 in SubDiv 21, commanded by LtCdr Sakamoto Eiichi.

Wartime History
At the start of the Pacific war on December 8, 1941, this sub participated in Operation "E" the Invasion of Malaya. Departs Sasebo with RO-34 and the Maki Unit to raid enemy forces off Malaya and Java.

On February 15, 1942 RO-33, I-53 and I-55 are ordered to intercept HMS Exeter and HMAS Hobart, but were unable to find them.

Next on February 20, 1942 transits Lombok Strait off Java into the Indian Ocean. During March 1 - 4 patrols off Tjilatjap. LtCdr Sakamoto sights several enemy transports and destroyers and attempts to attack them, but fails to score any hits.

10 March 1942: SubRon 4 is disbanded. The RO-33 and the RO-34 are reassigned to SubRon 6 of Vice Admiral (later Admiral) Inoue Shigeyoshi's (former CO of HIEI) Fourth Fleet, going to Palau and Truk. On April 4, 1942 she was assigned to the South Seas Unit with the RO-34 and departs Truk on April 15, 1942. The RO-33 arrives at Rabaul on 18 April 1942. LtCdr Kuriyama Shigeshi assumes command.

On April 20 1942, RO-33 departs Rabaul to reconnoiter Port Moresby to search the Jomard Passage for convoy routes and to reconnoiter the Russell and Deboyne Islands for suitable anchorages prior to the planned assault on Port Moresby. The RO-33 and RO-34 are later ordered to blockade Port Moresby and guide Japanese shipping into the area. On April 23, 1942 she returns to Rabaul.

On 1 May 1942, departs Rabaul as part of Operation "MO", towards the Jomard Pass in the Louisiade Archipelago with DesRon 6's light cruiser Yubari, four destroyers and a patrol boat escorting a transport Force of 12 transports and a minesweeper.

On May 5, 1942, RO-33 arrives off Port Moresby and on May 10, departs the patrol area bound for Truk. On May 23, 1942 departs Truk with sister submarine RO-34 bound for Japan.

On May 30, 1942 arrives at at Sasebo for overhaul and repair, departing on July 9 with RO-34 and returns to Truk on July 17-23 then departs for Rabaul with RO-34. On July 29, 1942 departs Rabaul to operate in the Coral Sea and off in the Port Moresby area and off the southeast coast of New Guinea.

On August 6, 1942 RO-33 was operating north of Murray Island off Queensland and proceeded into the Gulf of Papua. At 10:34am, spotted MV Mamutu and chased the vessel. Spotted around 11:00am, the submarine opens fire with the 80mm deck gun and scores repeated hits, sinking the vessel with great loss of life and only 28 survivors. Wartime accounts claim RO-33's captain Kuriyama ordered his crew to machine gun the survivors. Yet, the account of the sole survivor and Japanese sources dispute this claim, rather the submarine used only the deck gun.

On August 7, 1942 RO-33 was ordered to patrol the Indispensable Strait and reconnoiter the American landing area on Guadalcanal the contact Japanese forces on the island. On August 11, 1942 she arrives off Lunga Point and the next day at 1200, arrives off Cape Hunter and contacts Japanese forces. According to them, an enemy task force consisting of two carriers, two battleships, five cruisers and several transports were seen leaving Guadalcanal. LtCdr Kuriyama relays this information to headquarters. The next day, the sub delivers food to Japanese forces at Cape Esperance, then returns departs for Rabaul arriving on August 16.

On August 22, 1942 she departs Rabaul to patrol south of Samarai and then proceeds to Port Moresby. On August 26, 1942 LtCdr Kuriyama sends a regular situation report after arriving in his prescribed area. It is the last signal received from the RO-33. On September 1, 1942 the submarine is officially presumed lost off Port Moresby with the entire crew of seventy aboard.

Sinking History
On August 29, 1942 at 11:34 MV Malaita, escorted by destroyer HMAS Arunta, departed Port Moresby to escape enemy air raids bound for Cairns. At 1210, near the entrance to Fairfax Harbor at roughly at 9° 50' S, 144° 55' E MV Malaita was hit below the bridge on her starboard side by a torpedoe fired by RO-33 and takes on a heavy list to starboard. By 12:45, the crew abandons ship fearing she is about to capsize, but later re-boards and the damaged vessel is towed back to Port Moresby.

Searching for the attacking submarine, HMAS Arunta makes sonar contact with RO-33 ten miles southeast of Port Moresby and makes four attacks with Mark VII depth charges and observes a large oil slick at roughly 9°  36' S, 147° 6' E.

Wrecks & Reefs page 199 - 207
Combined Fleet
IJN Submarine RO-33: Tabular Record of Movement

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Last Updated
May 26, 2019


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