I found this ... naming the Japanese submarine I-177 - thought I'd post just in case anybody is looking for more information !
On 13 May 1943, No. 23 Radar Station RAAF had plotted a surface vessel which was located about 40 miles off the coast of Moreton Island. The blip was characteristic of a surfaced submarine. W.A.A.A.F. Operators P. Woodward, K. Rae and M. Hess reported the plots to the 8 Fighter Sector Headquarters in Brisbane. The plots were verified by the Commanding Officer of No. 23 Radar Station, Pilot Officer W. Fielder-Gill.
At approximately 4.10am on Friday 14 May 1943 the hospital ship A.H.S. Centaur, ablaze with lights, was torpedoed by Japanese submarine I-177 south east of Cape Moreton. The Centaur was struck in an oil fuel tank on the port side behind No. 2 Hatch. Centaur caught fire, and sank within two or three minutes .
Of the 322 persons on board, only 64 survived. Of the 12 Army Nurses on board, Sister Ellen Savage was the only survivor.
USS Mugford had been escorting the British Steamer "Sussex" on a voyage across the Tasman Sea. A lookout on board USS Mugford had spotted something on the horizon. Shortly after this an Avro Anson from 71 Squadron RAAF based at Lowood Airfield, spotted survivors in the water at 1400 hours on 15 May 1943 and radioed United States destroyer, USS Mugford, to "rescue survivors in water ahead". The Anson had been providing anti-submarine visual protection for Force "Z", which I assume was the USS Mugord and the British Steamer "Sussex".
Survivors in the first group of rafts recovered, told Lieutenant Commander H.J. Corey, the Captain of USS Mugford that they were from the hospital ship "Centaur".
The Naval Officer in Charge in Brisbane (N.O.I.C. Brisbane), Captain Edward Penry Thomas, received a signal from the USS Mugford that afternoon stating they were picking up many survivors of the Australian hospital ship Centaur at a position about 40 miles east of Cape Moreton. This was the first official indication on the mainland of this tragic event.
The Captain of USS Mugford requested the Anson to protect the "Sussex" while they continued to rescue the survivors of the "Centaur". A number of false alarms were reported on board USS Mugford of periscopes and torpedo trails. This caused a number of unnecessary distractions to the rescuers.
The survivors were mostly found within a 2 mile radius of the main oil slick and wreckage. They were in two larger groups and three smaller groups. USS Mugford rescued 63 men and 1 woman.
Corporal Maurice Peter Thomas (VX64840) a member of the medical staff of AHS Centaur escaped from the sinking ship and managed to locate a piece of planking at Daybreak. Cpl Thomas and Privates Jones and Private McCosker, and Privates Taylor and three of the ships crew all clambered on this piece of planking. They spent all day on the planking. Between midnight and daybreak the next day (Saturday) they heard the sound of engines about 3/4 mile away. Two emergency flares were light by some survivors on two rafts. They could not see anything. A crew member of Centaur indicated that it was a submarine engine that they could hear. He instructed the survivors on the rafts to extinguish the flares. The engines stopped soon after this.
Second officer, Mr R. G. Rippon, indicated that he had heard the engines of a surfaced submarine between mid-night and 4 a.m. on 15 May 1943. Able Seaman J. Cecich and Seamen's Cook F. Martin indicated that they had also sighted the submarine.
USS Mugford arrived in Brisbane on 15th May with the survivors. The Captain of the USS Mugford passed over the command of the rescue the N.O.I.C's chief staff officer, Lieut-Commander McManus. Further searches of the area were completed at 6 pm on the 16 May 1943 by U .S .S . Helm, H.M.A.S. Lithgow, and four motor torpedo boats without success.
Corporal Thomas (VX64840) remembered seeing four men from the AASC attached to the 2/12 Field Ambulance come on board Centaur in Sydney carrying their rifles. There have been many unsubstantiated rumours about armed troops on board Centaur and about her carrying stores of weapons and ammunition. The carrying of rifles by the AASC soldiers was in accordance with Article 8 of the "Convention for the Adaptation of the Principles of the Geneva Convention to Maritime Warfare" which allowed for the carrying of arms "for the maintenance of order and defence of the wounded and sick"
Sinking of the hospital ship "Centaur" by Japanese submarine I-177 on 14 May 1943 off the Queensland coast east of Brisbane
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http://home.st.net.au/~dunn/ozatwar/centaur.htm)
