Police have now completed the physical search for missing father and daughter Alan and Que Langdon who disappeared over a fortnight ago.

Langdon, 49, and his six-year-old daughter have not been heard from by family or friends since they left Kawhia Harbour in the Waikato on board a white catamaran on December 17.

The boat they are believed to be on is a 6.1 meter Wharram design catamaran, painted white, with white sails and the number T878 in black on the sail.

Langdon is an experienced and capable skipper and his daughter has had experience on boats also.

It was believed the pair intended to sail to the Bay of Island from Kawhia, but Police say it's unknown which direction they went after leaving the harbour. It's also been suggested the catamaran was 'stocked for a voyage”.

'There have been a number of unconfirmed sightings of similar vessels in the upper North Island area, but none of any significance since the New Year.”

'This search has covered a wide area of the New Zealand coastline as a consequence of Mr Langdon not giving anybody any notification of his intentions.”

Specifically, the search covered the western coastline of the North Island, from Wellington to Cape Reinga and the eastern coastline from Cape Reinga to the Bay of Islands.

Interpol have since been notified of the missing boat and its occupants, in the chance that he has sailed to Australia or the Pacific Islands.

The enquiry file will be maintained by the Waikato CIB and a response has been planned for any positive sightings or information that comes to hand.

'It is hoped that Mr Langdon will make contact when he arrives at his destination.”

The search was managed by the Waikato Police Search and Rescue and the Auckland Police Maritime Unit, with support from the Rescue Co-ordination Centre of New Zealand, Coastguard and the New Zealand Air Force.

Anyone with information on the whereabouts of Alan Langdon and his six-year-old daughter Que Langdon is being asked to contact their nearest police station immediately.

Information can also be left anonymously via the Crimestoppers 0800 555 111 line.

The boat Alan and Que Langdon are believed to be sailing on is a 6.1 meter Wharram design catamaran, painted white, with white sails and the number T878 in black on the sail. File Photo.