Food drop for trans-Tasman kayaker

Scott Donaldson has been attempting to row solo across the Tasman, but is now low on supplies. Photo / Double Ditch

An urgent aid mission will get underway today to drop vital supplies to a kayaker attempting a solo trip across the Tasman Sea.

Scott Donaldson, left from Coffs Harbour, north of Sydney and was now about 500km of New Zealand's coastline, Radio New Zealand reported.

The 43-year-old from Hamilton has run dangerously low on supplies after his trip was delayed by rough weather and technical issues.

Mr Donaldson's wife Sarah has asked Taupo rescue pilot John Fennell to make a drop of much needed supplies.

Mr Fennell told RNZ Mr Donaldson had a radio but he would still be trying to find a small speck in a big ocean.

"The trick is actually getting the container of contents down right in front of him or beside him and they're in a little parachute so we've got to be very accurate.

"It will be a bit of a challenge for us," Mr Fennell said.

Mr Donaldson's wife Sarah said she was very concerned for her husband's wellbeing."

[He's] dangerously low on food...the water, he can actually hand pump the water, but it's really about the weather conditions and the lack of solar that feeds the desalinator that converts the salt water to fresh water," she told RNZ.

Ms Donaldson said a text from her husband last night said he was looking forward to the supply drop and looked forward to spotting the plane.

He was "very tough mentally" and was looking forward to finishing the voyage in a couple of weeks in Taranaki, she said.

Mr Donaldson had been at sea since April 19.

The trip was a "long time coming" and had required an enormous amount of planning, Ms Donaldson said.

"He's very keen to get such a large venture under his belt, he's very keen to knock off something this big."