Taupo pilot John Funnell has already flown supplies out to kayaker Scott Donaldson, who struck trouble in his attempt to be the first person to kayak solo between Australia and New Zealand.
He successfully took food and water to Mr Donaldson last week, though there were some issues with the water containers fracturing. Some of them became mixed with salt water.
“We basically used the wrong containers,” Mr Funnell told AAP on Wednesday.
“He’s still got enough water to use until Friday, but we’ll take him some new ones tomorrow morning.”
Also in Thursday’s air drop will be some equipment to repair Mr Donaldson’s rudder, which has broken.
“At the moment he’s having to steer with his paddles, and that’s very difficult when a wave strikes,” he said.
“If he can repair the rudder he will make a lot more headway.”
Mr Donaldson, 43, is about 245 nautical miles (about 450km) away from New Plymouth. He may also have some rough weather to encounter with a storm on its way to New Zealand.
He left Coffs Harbour in NSW in April and hit trouble just 15 days from reaching his goal and 300 nautical miles west of New Plymouth, running out of food.
Overcast conditions also mean his solar-powered desalination plant doesn’t have enough power to supply him with the water he needs.
It is his second attempt to cross the Tasman after technical difficulties forced him to turn back last year.