Terrapin's 6th Patrol Far East
Terrapin fuelled at Exmouth Gulf and passed through Lombok Strait on the surface at night on 11th May, 1945.
Thence she proceeded to the vicinity of the Thousand Isles, west of Batavia, arriving in this area on the 15th. Here she had the misfortune to run aground on Arnemuiden Bank at 02:40 and was stuck for one and a half hours, getting off by jettisoning 15,777 gallons of external fuel, pumping out all internal tanks and finally discharging two of her forward torpedoes with stop valves shut and pistols removed.
The grounding was due to an abnormal set as a good radar fix had been obtained 26 minutes before and course was set to pass 1½ miles clear of the bank. The only apparent damage sustained was one leaky bow cap and to the log.
On the 17th two small vessels, one a motor lugger, the other a coal-laden schooner, were sunk by gunfire. The lugger, which was towing a prau, immediately beached herself when Terrapin opened fire, and about 40 soldiers, many carrying rifles jumped overboard and made for the beach.
Two days later Terrapin attacked a small tanker, with a frigate and one other escort, in shallow water, firing astern salvo. The captain ordered 60 feet, estimating that he was in about 15 fathoms, but struck the bottom at 57 feet on the gauge. No torpedo hits were heard so he stopped and waited.
About five minutes later the H.E. of an asdic-fitted vessel was heard closing and five charges were dropped fairly near but no serious damage resulted. After ten minutes another pattern of five charges arrived very close, buckling the hull in the tube space and causing extensive internal damage and considerable leaks.
It was decided to stick it out rather than attempt to free herself in such shallow water, such an attempt would certainly be very noisy and result in an uncontrolled surfacing as a lot of water would have to be blown in order to free the submarine. The frigate had six 4-inch guns and Terrapin would have presented a sitting target. The counter-attacks went on intermittently from 14:00 for five hours with the frigate using asdics with a steady transmitting interval.
The Captain was encouraged by his own previous experience of the inaccuracy of a destroyers gunfire when a submarine had been forced to the surface at 3,000 yards in broad daylight, and intended to surface after dark, relying on his small silhouette, surprise and his 4-inch gun. At 19:00 he blew main ballast and came off the bottom astern, very heavy forward.
On surfacing, the frigate was visible about 5,000 yards off. Terrapin turned to bring her astern and proceeded at 470 revolutions. The frigate made no attempt to close and gave no sign of having seen or detected the submarine.
About midnight a trial dive revealed hatches leaking badly but next morning a satisfactory dive and trim was achieved. With all W/T out of action, Terrapin set course for Lombok Strait and on the 21st was fortunate in falling in with USS Cavalla returning from patrol. Terrapin explained her situation and asked Cavalla to pass a signal to Commander Submarines, 7th Fleet. Cavalla did so, and stated that she would remain in company and escort Terrapin to Fremantle.
The transit of Lombok Strait was made in dark hours without difficulty and both submarines arrived in Fremantle on 27th May. The damage sustained by Terrapin was so extensive that she was unfit for further service without a major structural refit. It was encouraging to see the toughness of the pressure hull, which had been driven in to a depth of 12 to 18 inches in the torpedo room and had withstood the depth-charging without leaking.