Wreckage spotted in Fiordland's Doubtful Sound has been confirmed as a crayfishing boat, but its crew are still missing.
The nine-metre aluminium commercial vessel K-Cee with skipper Bruce Robert Gordon, 42, and crewman Darren James Allen, 37, last made contact on Monday morning.
An extensive search and rescue operation for the boat and Te Anau men began on Tuesday morning involving three helicopters, a small plane, four local fishing vessels and a Department of Conservation support boat.
Inspector Lane Todd is heading the search and told Radio New Zealand's Checkpoint programme on Tuesday evening the bow and other items found on Secretary Island at the entrance to Doubtful Sound belong to the K-Cee.
Mr Todd said an Air Force Orion sent from Ohakea will continue to search the area until about midnight.
There is also a helicopter on stand-by with night vision capability, but Mr Todd said flying across the sea in the dark is risky and it would only be sent out if new evidence is found.
Mr Todd said the search team hope Mr Gordon and Mr Allen have managed to get off the boat and into a liferaft and that is the focus of the search.
Meanwhile, the Southland Regional Council has stood its oil response team down, with no reports of fuel slicks so far.
The council says up to 5000 litres of diesel is thought to be on the boat.