Kiwi kayaker Scott Donaldson pushed back 100km in a week as he tries to cross the Tasman

Scott Donaldson's progress on June 8.

A Kiwi kayaking between Australia and New Zealand has been pushed backwards about 100km in the past week after a shift in the weather.

Scott Donaldson was crossing the Tasman Sea from Coffs Harbour to New Plymouth to raise money for asthma research.

He hoped to be the first person to ever make the solo kayak journey.

Donaldson's team leader Nigel Escott said this was on the back of a week of good progress towards New Zealand.

"He's a bit frustrated at the moment as he's at the mercy of the wind and tide."

Escott said the team has a plan to get Donaldson into better weather conditions.

The adventurer would travel in an anti-clockwise direction to try to escape the wind.

"[He] will make forward progress again once he gets into the more favourable wind and tides in a few days."

Donaldson had experienced similar challenges on his last attempt in 2014, when a once in a 40 year storm hit Taranaki and cut the journey short.

The former Rotorua man has already had to contend with 6m swells and fend off an attacking shark.

The 2.5m shark chased the kayak and was trying to bite off the rudder.

So far he's raised more than $1000 for asthma research.