Kiwi girl Que Langdon has been reunited with her mother in Australia. 

The six year-old and her father Alan Langdon went missing last month when they set sail from Kawhia, supposedly heading for the Bay of Islands, which sparked a search by police and coastguard. 

This week they turned up in New South Wales, more than three weeks after their journey began. 

Que's mother Ariane Wyler arrived in Australia this morning, on a flight from Switzerland.  

Private investigator Col Chapman confirmed to Newstalk ZB that Que had been reunited with her mother and was now in her mother’s care.

Alan Langdon said on arrival in New South Wales on Wednesday that he had planned to sail to the Bay of Islands for Christmas, a journey that might take a week. The plan went awry on the fourth day when one of the small yacht's two rudders broke.

He had materials aboard to repair the rudder but the weather didn't allow him to do so.

"The wind kept pushing us off shore and the sailing I was doing wasn't effective at getting us towards New Zealand."

He said he made the decision to head for Australia on about January 1. "We were pretty much blown here. I had limited choices in the angles I could take."

Langdon denied he sailed from New Zealand to Australia to avoid an ongoing custody dispute between himself and Que's mother, Ariane Wyler stating he has been Que's primary carer since birth.

"It's not a custody battle, it's an access thing," he said. "I've always been looking after [Que]."

Meanwhile, an experienced sailor told the Herald Langdon and his daughter should count themselves lucky that the notoriously fickle Tasman Sea was kind to them.

The encountered many weather fronts as they were blown towards Australia on a 27-day journey after one of the small craft's two rudders broke, sparking a large scale search by authorities.

The MetService said some of the lows would have produced large southwesterly swells that would have reached further north into the Tasman, where the father and daughter's 6.4 metre catamaran is likely to have been.

Langdon, 46, had no idea where on Australia's east coast he was when he rowed the catamaran, with Que on the tiller, into Ulladulla Harbour earlier this week.

He did not have a radio or satellite phone and was unable to let anyone know that they had been blown far out to sea. He was unsure whether an emergency position indicating radio beacon (Epirb) was onboard, Langdon told a reporter from the Milton Ulladulla Times on arrival on Wednesday.

He used the 8-metre mast to estimate that the biggest swells they encountered were 10 metres.

Yachtsman and commentator Peter Montgomery said the Tasman could be a "treacherous stretch of water" and it had caught out some of the best ocean-racing sailors. He said Langdon’s voyage was “foolhardy” given the size of 6m vessel.

“He should buy a Lotto ticket and be thankful that they are alive."