The lead navigator for a traditional waka expedition to Easter Island is hoping for a good push from westerly winds on the first leg out of Auckland on Friday.
The two double-hulled Maori canoes will sail nearly 19,000 kilometres from New Zealand to Easter Island (Rapanui) without modern navigational aids, re-creating Maori ancestral journeys.
Navigator Jack Thatcher, of Tauranga, has had 20 years' experience in traditional navigating and says the first leg will be challenging because of chilly temperatures but the winds are forecast to be favourable.
"We expect to get a good push out but it's going to be cold on that first leg so we're prepared for that."
From previous journeys he knows to expect stressful experiences in unpredictable weather, including 20m swells, electrical storms and water spouts in the tropics.
"You always run into things like that but it's about learning to relate to the ocean environment and just going with whatever it throws at you."
His wife and two daughters will no doubt fret the whole time he is away, he says.
"They're pretty used to it though."
The waka, with no cabins or mod-cons and carrying 22 crew, will use only the stars, moon, sun, ocean currents, birds and marine life to guide them.
The expedition, named Waka Tapu or sacred canoe and 20 years in the making, is being organised by the New Zealand Maori Arts and Crafts Institute and Te Taitokerau Tarai Waka and Mr Thatcher says it can be followed on the Waka Tapu website with regular updates from satellite tracking.
It is expected to take up to eight weeks each way, with outward stops in Raivavae and Mangareva, and Tahiti and Rarotonga on the return trip. After waiting out the cyclone season, they are expected to return by April.
A crew of 17 men and five women, ranging in age from 18 to 62 and descending from a number of iwi, has been chosen after an intensive four-month training programme and Mr Thatcher says the sailors all have a good range of skills.
"We have a number of old hands - one with nearly 30 years' experience - and some new recruits but they all know what they have to do."
Life on board each 17.3m-long waka will be challenging, with crew members taking turns sleeping in small compartments for three or four hours at a time and fishing constantly for fresh food. The waka will carry a stock of water and fresh and dried food but the crew will take minimal clothing.
For safety reasons, one person on board will have access to modern electronic gear for marine weather updates.
The expedition is headed by Northland navigator and canoe builder Hector Busby, who turns 80 this year.
He built both waka; Ngahiraka Mai Tawhiti last year, and Te Aurere, which has now sailed over 55,000km around the Pacific.
Institute director Karl Johnstone says the voyage aims to close the final corner of the Polynesian Triangle, defined by Hawaii in the north, New Zealand in the south and Rapanui in the east.
"While some historians believe the ancestors of Maori discovered this country by accident, there's no doubt their voyages to and from New Zealand were deliberate and planned."
He says public reaction to traditional navigating without modern instruments is varied.
"We collectively hope, however, that this voyage raises awareness about the wonders and interconnectedness of our natural world."
The waka will be launched from Auckland's Viaduct Events Centre on Friday.