Tauranga man Peter Blair is today in Picton organising an aerial search for his missing brother Kerry.

William Kerry Blair, 55, and his nine-metre aluminium hulled launch Erie left Tory Channel in the Marlborough Sounds on Saturday and extensive searches in Tasman Bay have failed to find any trace of Kerry or his boat.

Kerry Blair is believed to be somewhere off the top of the South Island

His boat was last seen near Cape Jackson about 5.30pm on Saturday.

Today the family is appealing for donations to mount an offshore search in a twin-engine plane before cyclone Lusi is due to arrive this weekend, making further searching impossible.

Peter says Kerry's daughter has opened a donation site at www.givealittle.co.nz through the Telecom Foundation to raise money for the search.

'We know he left Marlborough Sounds Saturday evening, and Sunday evening there was a cellphone ping or polling off the top of the West Coast.”

The boat could be off the West Coast Tasman area – or if something happened to the boat, it's possible it could be drifting north east towards Taranaki, says Peter.

'To go out to sea off the West Coast Tasman area, and for that flight we have to have a have a twin-engine plane. Anything more than 10 miles off the coast.

'They run at approximately $1200 an hour and they can't cover a huge area. They can cover ground pretty quick, but we are talking about a colossal area with a little ant running around trying to search for things.”

The Blair family's situation has some similarities to the search for the missing Malaysian Airlines' Dreamliner flight MH370. The government has sent an Orion to help in that search, and Peter is asking why an Orion cannot also help them.

'What's extra frustrating for the family is all the family is hearing continually is this Malaysian crisis and the fact the government can send an Orion over there when they have no idea where that plane is,” says Peter.

'But we can't get an Orion in the air here. We have an idea where my brother is within reason, but it's a huge area.

'Again, I go back to the Malaysian thing, they know where they last heard from the aeroplane, but then it could have gone anywhere from there.

'It's a similar situation with us. We know where he was from the cellphone usage, but he could have gone anywhere from there.”

Kerry is an experienced seaman and his behaviour is out of character, says Peter.

'He's 55 and he's been at sea since he was 10 years old. We don't know what he's thinking.

'We don't know if the boat's floating, whether he had some plan or whatever. We are totally confused. This is out of character for him; this is something he wouldn't normally do. We don't understand it, nobody does.

'That's where the money will go towards. We might have enough so that first thing in the morning, before the storm comes in, we can get a plane up and do a search.”