On the afternoon 28 September 1944 the Porpoise stopped a junk from Ketapang named the Mustika off the west coast of Borneo near Pontianak.
Seven commandoes boarded the boat and nine Malay crew were taken aboard the submarine.

Twelve minutes later, Porpoise submerged with both vessels making their way back west towards a forward operational base at Pedjantan Island.

Over the next two nights, 29–30 September 1944, the Rimau commandoes, the SBs, folboats and other stores were transferred from Porpoise to Mustika.

Once completed on 1 October 1944 the second conducting officer, Major Walter Chapman and Mustika's Malayan crew returned to Australia in HMS Porpoise. (
The Malay crew would be transported to Fremantle where they stayed for the rest of the war.)

Porpoise arrived safely back in Fremantle on 11 October 1944.
On 15 October 1944, Chapman, along with Corporal Ronald Croton, embarked in the submarine HMS Tantalus under the command of Lieutenant Commander Hugh Mackenzie.
This submarine was conducting an offensive patrol in the South China Sea and was due to rendezvous with the Rimau party on 8 November 1944.
On the afternoon 28 September 1944 the Porpoise stopped a junk from Ketapang named the Mustika off the west coast of Borneo near Pontianak. Seven commandoes boarded the boat and nine Malay crew were taken aboard the submarine.
Twelve minutes later, Porpoise submerged with both vessels making their way back west towards a forward operational base at Pedjantan Island.
Over the next two nights, 29–30 September 1944, the Rimau commandoes, the SBs, folboats and other stores were transferred from Porpoise to Mustika.
Once completed on 1 October 1944 the second conducting officer, Major Walter Chapman and Mustika's Malayan crew returned to Australia in HMS Porpoise. (The Malay crew would be transported to Fremantle where they stayed for the rest of the war.)
Porpoise arrived safely back in Fremantle on 11 October 1944. On 15 October 1944, Chapman, along with Corporal Ronald Croton, embarked in the submarine HMS Tantalus under the command of Lieutenant Commander Hugh Mackenzie. This submarine was conducting an offensive patrol in the South China Sea and was due to rendezvous with the Rimau party on 8 November 1944.
Operation Rimau