Danielle Wright set off in May with family friends David and Rosemary Dyche - the Nina's owners - and their son David Jnr. Experienced sailor Evi Nemeth was also on board, with fellow American Kyle Jackson and British traveller Matthew Wooton.
On June 4, a text from the Nina asked for an update on rough weather. There has been no contact since.
Authorities in NZ and Australia worked together to search an extensive area of the Tasman, but eventually called off the search.
Since then, the families of the Nina's crew have been raising money for their own searches. They maintain that, based on the combined experience of the crew and satellite images possibly showing the vessel, their loved ones are likely to be alive, well and waiting to be rescued.
"We are staying in Australia because we know of five other boats who drifted in the Tasman after being damaged, that took between four to 12 months before ending up on Australia's coast," she said.
"If history repeats itself, Nina could turn up any day now and we want to be close at hand to greet Danielle and the other crew."
Mr Wright decided to obtain his pilot's licence so he can plan his own searches and cut costs.
The couple have spent countless hours on planes cruising above the ocean trying to spot the Nina.
"We really think she's out there," Mrs Wright said. "A boat just doesn't get a hole in it and sink and disappear. It breaks up, there is evidence of it. There should be something by now if the Nina went down. There's not."
She said it was hard to sit in a plane for hours just staring at endless ocean.
"Especially as a mum. I dream, I absolutely sit there and daydream about what it's going to be like, to feel like, to see them ...
"Friends and family have asked us what we will say when finally reunited with Danielle. We're guessing there will be no words, just lots and lots of hugs. Others ask how we are holding up after the strain of waiting for six long months, especially at Christmas time. All I can say is this is going to make one great movie - lost at sea, drifting for months then stranded on an island."
To date, the Nina families have raised and spent around $500,000 on private searches.
With cash fast running out, Australian Ken Evers is asking flying colleagues to volunteer to search designated areas for the yacht.
He and two others will take the Wrights up on Boxing Day to search islands and reefs off the coast.
"[We're] hoping to find Nina stranded on one of them," Mrs Wright said. "There are so many little islands and reefs out there that a boat could get caught on. We're going to search every island on the Great Barrier Reef. But the Nina could still be drifting ... Nobody knows."
Mrs Wright revealed she and her husband had also been invited to join the Dyche family on the transtasman trip.
"Ricky and I couldn't leave our new business for three weeks, but the timing fell just right for Danielle to go."
Mrs Wright said the months following the Nina's disappearance had been "extremely hard".
"But not once have we felt like giving up the search. We have every confidence in Captain David and his highly experienced crew to take care of our only daughter, and we're sure Danielle will be returned to us."
Christmas was also going to be hard, but it would be easier for the couple being away from home and their family.
"We're in a new place with new people and a lot of things to do. We're not celebrating, no one in the family really is. It's a really sad time for us. We just hope and pray we find Nina ... there is a life for them on that boat if she's high and dry."
The Nina
• Built in 1928 for a race from New York to Spain, which it won. It won many other races around the world. American David Dyche III, 58, bought the Nina in 1988 and set sail with his wife and son in 2008. His wife wrote in a blog that their dream as a family was to circumnavigate the world, "meet people, learn about their culture and see the beauty of the world".
•The crew: Mr Dyche, wife Rosemary, 60, and son David Jnr, 17; family friend Danielle Wright, 19; Evi Nemeth, 71, a maritime technology expert and experienced sailor; Kyle Jackson, 27, a US traveller in New Zealand to visit a friend; Matthew Wootton, 35, a British Green Party activist.
