"It's totally out of character for him to be in this area in the boat he's in without notifying somebody."
Mr Blair said police told him and wife Sandy about Kerry's disappearance on Sunday, and they travelled to Picton on Monday.
He has barely slept or eaten since.
"He's out in a boat somewhere, hurt or injured. There's something wrong. [Eating or sleeping] is irrelevant. The priority is finding Kerry, my brother," he told the Bay of Plenty Times.
Mr Blair said his older brother's children, in their 20s, were "beside themselves".
The two brothers lost their sister to cancer last year.
Mr Blair said they had already searched the area close to the shoreline. Larger planes would allow the family to search further out to sea.
"We've pleaded for a larger plane, then we see them being sent overseas but we can't get them here," Mr Blair said.
"For the family it's heartbreaking, hair-pulling stuff. We are so frustrated."
The family have already paid for a small plane to go up four times. Each time it has cost them $1200 per hour, Mr Blair said.
One of Kerry's daughters set up a fundraising page on www.givealittle.co.nz to help pay for a larger plane.
The small plane was used again yesterday afternoon and it was expected to fly again this morning, but Mr Blair was well aware tropical cyclone Lusi was expected to hit parts of New Zealand today.
Mr Blair said his brother was well known throughout New Zealand's fishing fraternity and it was comforting to know local boaties were keeping an eye out for him while at sea.
The facts
*The boat has navigation equipment and a radio but neither has been used.
*The last-known possible sighting was near Cape Jackson about 5.30pm on Saturday.
*The signal from Kerry Blair's cellphone was last picked up off the top of the South Island on the West Coast side late Sunday afternoon.
*You can help the Blairs at www.givealittle.co.nz.
