Grave fears are held for seven people on board an historic schooner that was last seen off the north coast of New Zealand three weeks ago.
The vessel, Nina, went missing en route from Opua in the Bay of Islands to Newcastle, Australia.
The boat, built in 1928, left Opua on May 29 and has not been heard from since June 4, when it was about 370 nautical miles west-north west of Cape Reinga, Rescue Coordination Centre New Zealand (RCCNZ) said.
Of the people on board, six are Americans - three men aged 17, 28 and 58, and three women aged 18, 60 and 73 - and one was a British man aged 35.
The vessel was equipped with a satellite phone, a spot beacon which allows regular tracking signals to be sent manually, and an emergency beacon, RCCNZ said.
The emergency beacon had not been activated.
After concerns were raised by family and friends, the RCCNZ instigated a "communications search'' on June 14, using a range of methods to broadcast alerts to the vessel and others in the area.
RCCNZ search and rescue mission coordinator Kevin Banaghan said an RNZAF P3 Orion had completed two extensive searches this week spanning 484,000 square nautical miles north of New Zealand, based on the schooner being disabled and drifting or suffering damage but continuing to make progress towards Australia.
"Unfortunately, no sign of the vessel has been found,'' Mr Banaghan said.
"Our records show that conditions at the last known position for the vessel, on 4 June, were very rough, with winds of 80km/h, gusting to 110km/h, and swells of up to eight metres. We do hold grave concerns for the Nina and her crew but remain hopeful of a positive outcome.''
RCCNZ was liaising with the Australian Maritime Safety Authority and would continue to review search options, he said.
Weather conditions were expected to be calm in the vast area between New Zealand and Australia tonight before a low hits the area, MetService said.
In the next 72 hours, gales are forecast as well as a heavy swell north-east of New Zealand.