The search for a man thrown overboard in wild waves off the New South Wales coast resumed on Thursday, but authorities believe it will be a recovery mission.

The man, in his 60s, was lost overboard as his yacht was hit by a huge wave near Broughton Island, north of Newcastle, about 11.30am on Wednesday.

The search was suspended later the same day, as wild weather battered rescue crews.

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NSW Police Marine Area Command Superintendent Mark Hutchings told media on Thursday authorities had grave fears for the man, who had been missing for nearly 24 hours.

“Today we have launched Nemesis in the area and we are still looking for the man but unfortunately, due to the sea conditions, we believe this will be a recovery mission,” he said.

He described the weather on Wednesday as “a the perfect storm of conditions”, and said five other mayday calls were received.

All calls came from waters off Port Stephens, around the same area as the search zone.

“The sea conditions were up to six to eight metres with sometimes 50 knots gale,” Supt Hutchings said.

The missing man was believed to have been standing at the helm of the ship when a “large green wave” struck.

Marine investigators are assisting with the search.

Turbulent conditions continued on Thursday morning, with rescuers also battling to provide assistance.

Marine crews were injured after they are called to help a yacht, named M3, which was quickly approaching rocks at Seal Rocks, north of Broughton Island.

During the rescue, they were hit by a large wave. Five people onboard the M3 were able to make it to shore safely.

“They have received no injuries,” Supt Hutchings said.

“The rescue personnel and volunteers on marine rescue 40 were hit by the 40 and a number of them received minor injuries, one gentleman received a dislocated shoulder.”

Those in need of help were caught in rough seas as they sailed home from a yacht race that went from Pittwater to Coffs Harbour.