Police are working with Interpol in the search for missing yachtsman Alan Langdon and his 6-year-old daughter Que, with the search for his catamaran focusing on Northland, following tips from the public.
The pair have not been heard from since setting off from the Waikato for the Bay of Islands on a small catamaran on 17 December.
A police spokesperson said the possibility Mr Langdon had left New Zealand was one of several scenarios they were looking into as part of the search for the pair.
The focus of the search effort was currently in the Northland area, as police have received sightings of a vessel similar to Mr Langdon's heading in that direction over the past few days.
An extensive search involving the airforce, Coastguard air patrol and marine units has been under way since the police were notified on 27 December that Mr Langdon and Que were missing.
Police said the search included harbours and coastlines from Port Waikato, the western coastline from Kawhia to Cape Reinga, and the eastern coastline to the Bay of Islands.
Meanwhile, the mother of the missing 6 year-old has set up an online charity page to help with the cost of the search.
Golden Bay woman Ariane Wyler, who is currently visiting family in Switzerland, said she was desperate to be reunited with her daughter.
A private contractor Ms Wyler has hired plans to organise an aerial search of the West Coast down to Stewart Island.
She said it was the second time she had hired specialists to find her estranged husband and daughter.
The New Zealand Defence Force said last night that a Royal New Zealand Air Force P-3K2 Orion surveillance aircraft had joined the search for the missing six metre catamaran, and was to search the West Coast from Wellington to North Cape.
The boat is described as white with blue anti-fouling paint under the waterline with a sail number T878.
Child Recovery Services contractor Col Chapman told RNZ it was possible Mr Langdon was trying to make it back to Australia.
He said the pair separated close to two years ago following destruction of their boat in the cyclone that struck Vanuatu. Mr Langdon, an Australian citizen with family in New Zealand, was alleged to have taken Que to Australia. Mr Chapman said Ms Langdon's attempts to reach a custody agreement failed, and a legal process was started, but Mr Langdon allegedly fled to New Zealand with Que, where further court proceedings were started.
Mr Chapman said the lack of contact had now got to the stage of being highly unusual, even for an experienced sailor like Mr Langdon.
Maritime New Zealand had broadcast all-stations calls asking for sightings.