The submarines of the K6 sub-class were versions of the preceding K5 sub-class with greater range and diving depth. They displaced 11150NaN0 surfaced and 14470NaN0 submerged. The submarines were 80.5m (264.1feet) long, had a beam of 7m (23feet) and a draft of 4.07m (13.35feet). They had a diving depth of 80m (260feet).[1]
For surface running, the boats were powered by two 21000NaN0 diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600hp electric motor.[2] They could reach 19.75kn on the surface and underwater. On the surface, the K6s had a range of 11000nmi at ; submerged, they had a range of 45nmi at .
The boats were armed with four internal bow 53.3cm (21inches) torpedo tubes and carried a total of ten torpedoes. They were also armed with a single 76.2mm L/40 anti-aircraft gun and two single 251NaN1 AA guns.[3]
Ro-47 was laid down as Submarine No. 388 on 28 December 1942 by Mitsui Zosensho at Tamano, Japan.[4] She was launched on 30 August 1943, and was renamed Ro-47 that day.[4] She was completed and commissioned on 31 January 1944.[4]
Upon commissioning, Ro-47 was attached to the Maizuru Naval District.[4] After Japanese forces sighted an Allied task force heading toward the Palau Islands, Ro-47 and the submarines,,, and received orders on 27 March 1944 to proceed to patrol areas east of the Palaus.[4] Ro-47 got underway from Kure, Japan, that day, called at Tokuyama to refuel from 28 to 29 March 1944,[4] and set out for her patrol area. On 5 April 1944 she was recalled to Kure, which she reached on 13 April 1944.[4] She was reassigned to Submarine Division 34 in the 6th Fleet on 14 May 1944.[4]
On 13 June 1944 the Combined Fleet activated Operation A-Go for the defense of the Mariana Islands, and that day the commander-in-chief of the 6th Fleet, Vice Admiral Takeo Takagi, ordered all available Japanese submarines to deploy east of the Marianas.[4] Accordingly, Ro-47 departed Yokosuka, Japan, to begin her first war patrol, assigned a patrol area in the Marianas off Saipan, where the Battle of Saipan began with U.S. landings on the island on 15 June 1944.[4] In July 1944, the 6th Fleet ordered most of its submarines, including Ro-47, to withdraw from the Marianas.[4] Ro-47 departed her patrol area on 10 July 1944 and on 16 July arrived at Maizuru, where she began repairs and an overhaul.[4] She later moved to Kure.[4]
On 15 September 1944, U.S. forces invaded the Palau Islands, landing on Angaur and on Peleliu.[4] Ro-47 got underway from Kure on 17 September 1944 with orders to attack the U.S. invasion fleet off Peleliu, assigned a patrol area south of the Palaus.[4] On 24 September 1944, she received an order to proceed at full speed to a new patrol area in the Philippine Sea east of the Palaus.[4] The Japanese never heard from her again.[4]
The United States Navy destroyer escort was steaming independently in the Philippine Sea northeast of the Palaus on a voyage from Peleliu to Guam when at 01:03 on 26 September 1944 she detected a vessel on the surface on radar at a range of 9200yd.[4] When she closed with it and challenged it, it disappeared from radar, indicating a diving submarine.[4] McCoy Reynolds then detected the submarine on sonar at a range of 2500yd.[4] At 02:18, McCoy Reynolds launched the first of six Hedgehog barrages.[4] After the sixth attack, the crew of McCoy Reynolds felt a large underwater explosion at 06:15 and subsequently observed oil and debris rising to the surface, marking the sinking of a Japanese submarine at 9.3167°N 180°W.[4]
The submarine McCoy Reynolds sank probably was Ro-47.[4] On 2 November 1944, the Imperial Japanese Navy declared Ro-47 to be presumed lost off the Palau Islands with all 76 men on board.[4] She was stricken from the Navy list on 10 March 1945.[4]