KEY POINTS:
Two men attempting to become the first Australians to paddle across the Tasman are battling physical and emotional exhaustion, as well as the likelihood that a competing craft will steal their glory.
Eight-metre swells continue to swamp their custom-built kayak as Sydneysiders James Castrission, 25, and Justin Jones, 24, paddle towards Auckland in rough conditions.
The pair set out on their 2200km journey on November 13 from Forster, on the NSW mid-north coast.
They reached their halfway point in early December but went around in circles for two weeks in attempts to dodge persistent head winds and a whirlpool of ocean currents.
They are now 540km from Auckland, but their support team estimates the men have paddled an extra 1000km as a result of their unplanned detours.
"They're physically and mentally exhausted, and morale has gone to its lowest point in the journey," said support team member Tom Mitchell.
"Basically, they're sick to death [of trying] to get their arses across to New Zealand."
For the past two days, they have made big advances, paddling more than 200km, and expect strong westerly winds to push them similar distances for another two days.
But strong tail winds have brought big seas that make paddling difficult.
The kayak enters the middle of 8m swells, submerges slightly and resurfaces to repeat the challenge.
"And on top of that, they've only been getting one hour of sleep a night because the seas are so rough," Mr Mitchell said.
"They've described it as trying to sleep with 12 kids jumping up and down on the bed."
Their original arrival date of Christmas Eve has been extended repeatedly, but the support team expects the pair to arrive in New Zealand as early as January 7.
Crossing in the opposite direction, a four-person rowing team of Steven Gates, Andrew Johnson, Kerry Tozer and surf boat champion Sally Macready set out on November 29 from Hokianga Harbour.
The conditions that hammered Castrission and Jones favoured the foursome, who reached their halfway mark in just 15 days.
They are now just 370km from Sydney Harbour and are expected to arrive on New Year's Day or the next day.
The larger team has also endured rough conditions and a near-miss with a freighter on Christmas night.
But on Boxing Day, they encountered a pod of dolphins and good conditions.
"The weather was glorious. We finally struck a favourable current and it was great to be on the ocean," Gates said in a statement.
Jones and Castrission are not expected to reach land first, since easterly headwinds are forecast to return on Sunday.
Mr Mitchell said the pair are not bothered that Gates' team will arrive first, especially since they have twice the rowing capacity.
"Everything that's held our boys back has given the other team the advantage to keep paddling hard to make it there before them," Mr Mitchell said.
"And the more people you have, the less prestigious it is."
He said solo kayaker Andrew McAuley would have been the ultimate champion.
He attempted the crossing to New Zealand's Milford Sound in February, but disappeared after sending out a garbled distress signal only about 50km from his destination.
His partially submerged craft was located drifting in the ocean, but his body was never found.
- AAP
