Rescue crews searching for a classic American schooner carrying seven people believe the boat sank between New Zealand and Australia, although they haven't given up hope of finding survivors.

A third day of aerial searches Friday turned up no sign of the 85-year-old wooden sailboat or its crew. Named Nina, the boat left New Zealand on May 29 bound for Australia. The last known contact with the crew was on June 4. Rescuers were alerted the boat was missing on June 14, but weren't unduly worried at first because the emergency locator beacon had not been activated.

The six Americans on board include captain David Dyche, 58, his wife, Rosemary, 60, and their son David, 17. Also aboard was their friend Evi Nemeth, 73, a man aged 28, a woman aged 18, and a British man aged 35.

The leader of Friday's search efforts, Neville Blakemore of New Zealand's Rescue Coordination Centre, said it's now logical to assume the 70-foot  boat sank in a storm but added that it's possible some crew members survived either in the life raft that was aboard or by making land.

On the day the boat went missing, a storm hit the area with winds gusting up to 68 miles per hour and waves of up to 26 feet.

Blakemore said the Southern Hemisphere winter months tend to produce the year's worst storms, although he added that he wouldn't normally expect a sturdy and well-maintained craft like the Nina to sink in a storm like the one in early June.

Friday's search focused on the coastline around northern New Zealand, including the small Three Kings Islands. Rescuers were looking for wreckage or the life raft.

Blakemore said plane searches earlier this week covered a wide band of ocean between New Zealand and Australia. He said searchers were considering their options for the weekend.

He said the logical conclusion is that the boat sank rapidly, preventing the crew from activating the locator beacon or using other devices aboard, including a satellite phone and a spot beacon. He said that unlike many locator beacons, the one aboard the Nina is not activated by water pressure and wouldn't start automatically if the boat sank.

Dyche is a qualified captain, and he and his family are experienced sailors. Blakemore said the family had been sailing around the world for several years and was often joined on different legs by friends and sailors they met along the way.

Susan Payne, harbor master of the St. Andrews Marina near Panama City, Florida, said the couple left Panama City in the Nina a couple of years ago and sailed to Mystic Seaport in Connecticut, where they prepared for the trip.

New Zealand meteorologist Bob McDavitt was the last person known to have been in contact with the schooner, when the boat was about 370 nautical miles west of New Zealand.

He said Nemeth called him by satellite phone on June 3 and said, "The weather's turned nasty, how do we get away from it?"

He advised them to head south and brace for the storm.

The next day he got a text message, the last known communication: "ANY UPDATE 4 NINA? ... EVI"

McDavitt said he advised the crew to stay put and ride out the storm another day. He continued sending messages the next few days, but didn't hear back. Friends of the crew got in touch with McDavitt soon after that, and then alerted authorities.