Members of the NZ Navy have joined the Police Maritime Unit on board the Lady Elizabeth lV in the search for a man lost overboard from his vessel in the Marlborough Sounds.
Craig Alfred Partridge, 45, from Marlborough, went missing from a launch early on Tuesday morning. Police said he had not been wearing a lifejacket.
The Navy will use its sophisticated sonar equipment to provide an accurate picture of the entire seabed within plotted co-ordinates in the search area.
Shoreline searches are continuing in the Endeavour Inlet area, near the northern entrance to Queen Charlotte Sound.
Furneaux Lodge owner Geoff Faulkner said on Tuesday that he believed the man was with his daughter and her partner on a commercial fishing boat.
They left the lodge about midnight to go back to Marine Head, near the entrance to Endeavour Inlet, he said. One of the people on the boat is believed to have sent out a mayday call, saying a person had been lost overboard.
The conditions had been flat and calm, he said.