The "deeply distressed" mother of a 6-year-old girl missing with her father on a homemade catamaran for 11 days has spoken of her shock at their disappearance.
Alan Langdon, 49, and his daughter Que left Waikato's Kawhia Harbour bound for the Bay of Islands on December 17 and have not been seen or heard from since.
Police have grave concerns for their welfare and a massive search is under way.
Speaking for the first time, the girl's mother, Ariane Wyler, told the Herald that she separated from Langdon last year and has since been in a protracted custody battle.
"I am deeply distressed about this current situation and miss my daughter Que greatly."
She hadn't seen her daughter for 20 months.
She spoke yesterday with Langdon's parents Kay and Walter, who still live in Kawhia, the tiny seaside village south of Raglan, and was shocked at hearing Langdon and Que had been reported missing.
"I am strongly convinced that they both are alive, well and safe," said Wyler, who lives in Golden Bay in the South Island but is on holiday in her native Switzerland.
"I sincerely hope that they are okay and oblivious to the fact that they are being searched for.
"I believe in Alan Langdon and his capabilities as a sea-going person.
"My gut feeling tells me that they are further offshore to the west."
Police have not yet contacted her, she said.
She described Que as a "beautiful daughter" and a "gorgeous little person".
Que spent her first four-and-a-half years living on the 14m catamaran Sanyasin, Wyler said.
In March last year the family of three was in Port Vila, Vanuatu when Cyclone Pam struck.
The category 5 severe tropical storm battered the island, claiming up to 16 lives and sinking at least 20 boats.
It sank Sanyasin and the Langdons were lucky to escape with their lives.
Langdon and Que lived at Mary Smith's home in Kawhia after returning from overseas at the end of July.
The family had used her home as a base for years in between travels.
Langdon, a stay-at-home dad, built the catamaran the pair left Kawhia in on Smith's front lawn. Smith raised the alarm on Boxing Day after Langdon and Que had been at sea without word for nine days. She described Langdon as a competent boatsman who doted on his daughter.
"She was his best mate. He loved her to the max," Smith said.
"We're hoping that they're safe and well. All we want is to hear from them, that they're okay. We can't do anything else."
Before Langdon and Que set sail, Smith slipped some Christmas presents and a letter into a bag for the pair and put it on board the white and blue catamaran.
"Hopefully they did open it on Christmas Day or whenever. It was just some clothes and lots of sweets, of course, which he doesn't like her to have too much of."
The Langdons are well-known in the Kawhia area and have a long association with the sea.
Langdon's grandfather operated a fishing vessel out of Kawhia Harbour for many years.
Police are focusing on establishing the pair's whereabouts and the Auckland Maritime Unit is searching shorelines north of Auckland.
Yesterday, a spotter plane searched the coastline between Mokau and Port Waikato up to six nautical miles out for Langdon's catamaran but found nothing. Police refused to answer specific questions or say if they believed there were any suspicious circumstances.
"We continue to make inquiries as to the pair's whereabouts, and have an open mind as to what the situation may be," a spokeswoman said.
"We urge any member of the public with any information or sightings to contact police."