Having reached the end of a year-long stint aboard the guided missile frigate HMAS Newcastle, the skinny youth suspected his crewmates were planning a hazing for his last night at sea.

"When leaving the ship it's a navy tradition where everyone gets a little beaten-up and bruised," he told a Sydney court martial this week.

"The majority of the guys who had their final nights at sea were just pulled out of their racks and had Never-Seez [ship's grease] or something poured on them," he said.

But his time, the youth said, things were different.

As he emerged from a valve repair job in the bowels of the ship in mid-August, 2011, he was allegedly grabbed from behind and carried backwards into the recreational space near HMAS Newcastle's 3^rd aft mess.

"When I got to the rec space I was spun around and thrown in … there were people waiting," he said, appearing to fight the urge to be physically ill.

"I turned on my heels and tried to make an exit and was forcibly stopped by AS Walter in the doorway.

"I was grabbed, pinned down and tied up with cable ties … in a hog-tie type fashion."

He told the court that three of his fellow sailors pulled his pants and underwear down as he tried unsuccessfully to struggle free, and around 30 other crewmates looked on.

Then one of his crewmates rubbed what he thought was deep heat and then vegemite between his buttocks, producing a strong "burning sensation".

"At this point I was pretty damn frightened of what was going on, sir," the sailor said.

"I was yelling and screaming 'what the f--- is going on! Stop! What's happening?!' "

"I was rolled back onto my stomach at which point I felt something trying to be inserted into my anus."

The sailor said he did not see what was being inserted into him, or by whom, but that shortly after, another crewmate, Able Seaman Michael Thompson, tried to force a rubber chicken that smelt strongly of vegemite and deep heat into his mouth.

"It didn't go into my mouth because I bit my lip," he said.

The sailor was then allegedly carried to the ship's amenities area and had a dark liquid poured over his head, burning his eyes and face and causing him to scream out in pain. He was then allegedly cut lose and left sitting in the bottom of a shower under cold water.

The court martial heard that it wasn't until two years later, as he stood in the "smoking pit" at the Cairns Naval base, that the sailor spoke to another sailor about what had happened.

As he chatted to a colleague about revelations of brutal hazings aboard HMAS Ballarat, the able seaman allegedly revealed that similar treatment had been dished out to him.

"I was afraid that if I spoke up there would be repercussions," he said.

The colleague passed the young man's allegations on to his superior officers, who initiated an investigation by the Australian Defence Force Investigation Service.

Four of the alleged victim's crewmates were charged with a range of charges including sex without consent.

Two, Able Seamen Rohan Martin Angre and Michael Daniel Thompson, pleaded guilty to lesser charges on Monday, while Able Seamen Mitchell Summers and Lee Walter are still being tried on all charges.

As this week's hearing at Defence Force plaza unfolded, counsel for Able Seaman Summers launched a scathing, extended attack on the credibility of the alleged rape victim and described his claims as a "ridiculous story".

"Your allegation of sexual assault is a concoction," defending officer, Lieutenant Paul Hogan said to the sailor.

"No sir, I'm not that much of a sick person that I'd make something like that up," the able seaman responded

"It's a ridiculous story, I suggest, for the smoking pit. You made it up as some sort of war story," Lieutenant Hogan continued.

"No, it happened sir," the sailor replied.

It emerged that the sailor's career had been on thin ice for more than a year because of concerns about excessive alcohol consumption, which stemmed, in part, from the fact that following the alleged incident he was proscribed medication for depression, anxiety and narcolepsy.

Lieutenant Hogan also accused the sailor of concocting the rape allegation so that he could make a claim for compensation.

After appearing, initially, to deny that he had made any compensation claim, the young sailor conceded later that he was seeking a "lump sum" for "permanent impairment".

"This is all about the cash is it not?" Lieutenant Hogan said.

"No sir," the sailor replied.

The court martial continues.

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