Tim Nguyen, 37, of Bankstown, had gone fishing only four times in his life before he got into a mate's boat and headed out towards Cape Banks at Botany on Thursday.

He hasn't been seen since the boat capsized in large swell at 7pm.

Mr Nguyen's friends swam to shore, then clambered over the rocks to safety, suffering bruising and cuts on the way.

Lifeguard supervisor Peter Halcro said he found the two men falling in and out of consciousness.

"They managed to climb up onto the golf course and I was treating them on the golf course," he said.

"The way the swell had been building during the day they were lucky to be able to have scrambled over the rocks.

"They were unresponsive at the start and with a bit of oxygen they came good."

Divers, jet-skis and rescue boats returned to the area at the tip of the Botany National Park on Friday morning to search for Mr Nguyen.

His fiancee stood on the rocks with Mr Nguyen's sister-in-law and two brothers as the search continued.

Rescuers have retrieved lifejackets that were floating in the sea.

Mr Halcro confirmed that, while the lifejackets were on board the boat, the three fishermen did not have them on.

"Lifejackets are key when you are out on the boat," he said.

An anchor, pieces of clothing, a fish finder and rope have also been pulled from the water.

Westpac Life Saver Rescue Helicopter chief executive Stephen Leahy said the seas had reached two metres when the boat flipped.

"Really we had about 15-20 minutes of reasonable light to search with," he said.

It has been a horror fortnight for drownings along the NSW coast with 12 people losing their lives, including while rock fishing and swimming.

"A lot of these deaths could have been preventable if they were wearing a lifejacket," Mr Leahy said.

*/ ]]>