A navy frigate has been deployed to rescue William Kerry Blair's boat, seen floating northwest of New Plymouth.
The Wellington was last night heading from Wellington to an area about 200 kilometres off Port Taranaki, where the missing 9-metre boat Erie was last seen.
Police said heavy seas were hampering the frigate's progress and it was not expected to reach the area until early today.
Police officers on board will try to board and recover the Erie.
The Rescue Co-ordination Centre analysed wind speeds and drift patterns to gauge how far the boat drifted after the weekend storm.
Mr Blair, 55, has not been heard from since he left Erie Bay, in Tory Channel in the Marlborough Sounds, about 4pm on March 8.
His boat was last seen near Cape Jackson about 5.30pm that day.
Mr Blair's younger brother, Peter Blair, said the naval deployment was the most significant step in the search operation.
"This is our best possible chance of retrieval," he said. "We are feeling all sorts of things. We are very happy the navy has been deployed but frustrated and exhausted . . . We know they have procedure to go through but it would have been nice if the boat had gone out four or five days ago before the storm."
The family still clung to hope.
"It has been particularly hard on the younger members of the family," he said. "We are holding on to the hope he is still on board. It has been over a week [since he went missing] but our last feedback on the condition of the boat was that it appeared watertight and remained seaworthy.
"I have full confidence in his ability as a seaman."
- The Marlborough Express
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