A man has detailed how he tried to end his own life after being raped repeatedly as a Navy apprentice in Sydney.

Ken McIlwain, now in his 60s, joined the Navy as a 16-year-old, and was based at the HMAS Nirimba training base in Schofields in the city's west.

He was frequently raped by two men in the early 1970s, sometimes as often as once a week, leaving him with injuries to his backside.

Eventually he took three bottles of Valium in an attempt to end his life and was hospitalised for three months before being kicked out of the navy on medical grounds.

Mr McIlwain kept his story a secret for 40 years as he built a life and a family, first revealing it in 2014 after a report on the news about the Skype sex scandal brought his experience bubbling to the surface.

Speaking to Channel Ten's The Project on Wednesday night, he disclosed harrowing new details of the first time he was attacked.

"About a year after I joined we moved into a new set of barracks and I used to do the ironing for one of the seniors," Mr McIlwain said.

"I took it up one time and he usually just [paid] me a small amount of money to do it, but this time he grabbed me and threw me on the bed and had oral sex with me, telling me that was my payment. There was also someone else in the room."

He sought help from the base's medical officer three times and was initially rebuffed, being told pain in his backside and stomach was just "anxiety".

"The second and third time I went back I told the medical officer what was happening, that I was being raped," Mr McIlwain said, his voice beginning to shake.

"They kept giving me bottles of Valium, and in the end, on the last occasion I was raped, I went down to the shower and I was washing myself and I suppose I was embarrassed and just ashamed.

"And at that time I decided I'm not going to get away from this, so I went and got a can of Pepsi and I remember I had three bottles of Valium left, so I remember counting them, there was 72 [pills]. I took the whole lot to commit suicide because I was happy to go. I mean there was no way, there was no way I could get out of it."

After going to hospital, he was admitted to Concord Psychiatric Hospital for several months. He said his parents came to visit him, and when he told them what happened, his father beat him and called him a liar.

"From that day I said I would never tell another soul, because the only person that believed me was God," he said. "From that day I said nothing, until the Skype issue on TV."

The rapes had a profound impact on him as he got married and started a family, as he dealt with certain "triggers" like bulk-buying the same brand of soap he had used to wash himself with after each assault, in case he ran out.

"I can talk about it now without tears," he said. "I went through a lot in the last five years. I just hope there's other people out there right now, other Defence people, who see me tonight and say goodness me, I'm going to speak about it. You need to."

He urged other victims of Defence abuse to detail their stories to the Royal Commission. "Don't give up," he said. "Just don't give up."

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