Experienced sailor Mal Lennon is feared drowned after being swept from a yacht off the NSW coast in "perfect storm" conditions.
Mr Lennon, 62, was believed to be at the helm of the 36ft yacht Amante when he was struck by a huge wave that swept him into the water off Broughton Island about 11.30am on Wednesday.
Crew members and investigators believe Mr Lennon was struck by a "green wave" - a wall of water that had not yet broken.
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Rescuers are still searching for Mr Lennon but believe there is little chance he could have survived the night in the rough seas without a life jacket.
"Sea conditions were up to six to eight metres with sometimes up to 50-knot gales," NSW Police Marine Area Command Superintendent Mark Hutching told reporters.
"Due to the sea conditions we do believe that this will be a recovery mission."
Mr Lennon, who has an adult daughter with his former wife, is a civil engineer by trade but has been a property manager with Cadence Australia for a decade.
His boss Todd Murphy, whose father has known Mal for more than 40 years, told AAP the news had come as a shock to staff who were numb and in distress.
Mr Murphy described Mr Lennon as a "one off" and a "smart cookie" who is passionate about his family, his work and sailing.
"A lot of young people work for us and Mal was a good role model for them and a much-loved bloke," he said.
"Mal was a one off. He was an incredibly smart person. It's of no surprise he was on a boat doing what he loved."
Mr Lennon grew up with three siblings in the iconic property Wanganui at Longueville, which sold last year for almost $6.5 million.
Amante, owned and skippered by Dennis Cooper, was returning to Sydney after coming 33rd in the Club Marine Pittwater to Coffs yacht race over the new year break.
Marine rescuers responded to five other mayday calls and four calls for help from other yachts in the area making the trip.
One rescue call came from yacht M3 after a sailor spent seven hours stuck up a mast.
The crew was able to rescue the man but again called for help as they were swept towards rocks.
Rescuers made three attempts to throw a tow rope to the yacht but both vessels were struck by a large wave which forced five people on board M3 to abandon ship and swim to shore.
No-one on M3 was injured, while a number of people on the rescue boat suffered minor injuries.
Supt Hutching praised rescuers and volunteers who braved the rough conditions.
"The Amante incredibly stayed on scene for a number of hours to help along with another yacht called Jem," NSW Police Marine Area Command Superintendent Mark Hutching told reporters.
Those boats were escorted back to Port Stephens when conditions worsened and were replaced with fresh crews who have returned to the search.
