When diver Rob Hewitt floated alone in the sea off the Kapiti Coast for 75 hours, prayer, reciting family names and clutching his legs into the fetal position helped him to survive, according to a new study of his near-death experience.
The brother of former All Black Norm Hewitt, who grew up in Hawke's Bay, was diving with mates when caught in a rip in February 2006. He surfaced 600m behind their boat and was quickly pushed further away by the tide.
In the ensuing days he became extremely cold and severely dehydrated, his skin was nibbled by sea lice, he suffered hallucinations and he made two half-hearted attempts to end it all.
• Robert Hewitt's story of survival
Researchers have analysed his ordeal in an article in the journal Diving and Hyperbaric Medicine. They say that at 16-17C, the water temperature when Hewitt was floating back and forth between Mana Island and Kapiti Island was enough to kill him within a few hours.
"Rob's story is not only one of buying time by his body-shape and strength of his equipment, but also the psychological battles played out from the moment he realised the boat he was supposed to be on had gone," said the study's leader, Dr Heather Massey, a human physiology expert at the University of Portsmouth in Britain.
Hewitt had a buoyancy compensator, that kept him floating with his head above the water, and a crayfish and four kina in his catch bag.
An experienced navy diver, he was fit, 1.8m tall and weighed 100kg, giving him a decent amount of insulation, and he was wearing a 5mm-thick wetsuit. The researchers said he was more likely than a lean person to retain a warmer core temperature.
"By adopting a fetal position and keeping movement to a minimum, he further reduced heat loss," the researchers said in a university publication.
One of the researchers, survival psychology expert Dr John Leach, said Hewitt - who described his survival experience in the book Treading Water - prayed every prayer he could remember, swore at God, repeated the names of family members like a mantra, and spoke to them individually.
"Reciting prayers and names of family members as a litany or mantra serves to increase the hope of surviving and to reduce anxiety through both physiological and psychological mechanisms."
Prayer and mantras slowed breathing, the researchers said. And they were thought to use the same brain resources as worrying and anxiety, thus allowing a survivor to steer the mind away from worries, reducing anxiety.
Many long-term survivors, including hostages, had made mental lists of things they wanted to accomplish. This kept the brain engaged, implied hope in a future, and prevented the inertia which could lead to apathy.
Leach said: "A routine serves to increase the amount of spare capacity in working memory for planning and decision-making. Rob set himself the simple but important task of repeatedly and systematically checking all his gear."