Shoreline searches for a missing yacht have been suspended overnight with still no sign of the vessel or its passengers.
A helicopter with three search and rescue observers left Hamilton at 11.30am to look for any signs of the Nina, its life raft or any of the seven people on board.
The helicopter scoured the coast as far south as New Plymouth before refuelling and heading back to Port Waikato.
David Dyche IV, 17, his father, David Dyche III, 58, and mother, Rosemary, 60, have not been seen since May 29, when they and four others left the Bay of Islands for Australia on the 21m vintage racing schooner Nina.
A text message sent to a meteorologist on June 4 asking for advice about continuing to sail in bad weather was the last communication from the crew.
The Nina was destined to arrive in Newcastle, Australia, 12 days later.
A twin-engine fixed-wing aircraft searched the shoreline and coast starting at Tauroa Point, along Ninety Mile Beach, north of Northland, and out to and around Three Kings Islands yesterday.
There was no sign of the vessel or crew and a mechanical fault with the aircraft this morning meant the crew switched to a helicopter for today's mission.
Rescue Coordination Centre New Zealand's (RCCNZ) Chris Henshaw said they were looking at drift modelling and running a number of different scenarios to work out where the boat and crew might be.
Nina was equipped with a satellite phone, a spot beacon which allowed regular tracking signals to be sent manually, and an emergency beacon. The beacon had not been activated.
Henshaw said the estimated 12-day sail was "overly optimistic'' and the Australian Maritime Authority said June 25 was a more realistic arrival time.
"Because the yacht left from New Zealand waters it's our responsibility to run the search, but we are in constant communication with Australia Maritime.''
RCCNZ is in regular contact with the crew's family and one relation who lives in New Zealand.
"We are also regularly updating the American and UK consuls,'' he said.
"We had one unsubstantiated report of a yacht with the same name approaching the Newcastle area but we have found that to be untrue.''
The search began on June 14 when family and friends of the crew contacted RCCNZ with concerns for the vessel's safety.
The Royal New Zealand Air Force Orion has completed two extensive searches this week.
At the time the schooner is thought to have gone missing sea conditions were eight metres and winds were gushing to 65 knots.
A debrief will be held overnight as to what happens tomorrow.
- Fairfax Media