A father and his seven-year-old daughter should count themselves lucky that the notoriously fickle Tasman Sea was kind to them, say experienced sailors.
Alan Langdon and his chirpy daughter Que, 6, 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.
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.
"Swells of 3-5 metres are common with these types of systems ... however it is possible to get a handful of much larger waves," meteorologist Claire Flynn told the Herald.
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.
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.
"It can just turn mean and nasty very quickly, with liquid Himalayas," Montgomery said.
Safety regulations for offshore racing were significant strengthened after tragedies such as the loss of six lives during a storm that sunk six boats during the 1998 Sydney-Hobart further to the south.
"I think it was foolhardy," Montgomery said of the catamaran's voyage. "He should buy a Lotto ticket and be thankful that they are alive."
Ray Haslar, a veteran of 15 Sydney-Hobart races and chairman of the Bay of Islands Sailing Week, New Zealand's premier keelboat regatta, said there had been no significant storms between New Zealand and Australia in the past month.
"It can be millpond calm or a hurricane. It's the luck of the draw.
"It's not a boat I'd go across the Tasman in ... but God looks after these people sometimes and I think he had a pretty uneventful trip across."
Haslar said the catamaran would not have met safety requirements for a category 1 certificate required for offshore sailing and to get customs clearance.
Coastguard operations manager Ray Burge said the most important message was to expect the unexpected no matter where you planned to go boating.
"There were 2500 odd incidents last year that were intended."
"The west coast is a bit more exposed than other waterways," Burge said. "Had he had a locator beacon the boat could have been located."
"If he's got the equipment why not take it? We have a lot of boaties who fish off the west coast out of Kawhia and Raglan, they have that type of equipment for not going very far off shore. So an extended voyage, such as heading to the Bay of Islands, if he had that equipment it would make sense to take it."
Burge said It was standard advice for sailors to carry two types of waterproof communication, life jackets, and to be aware of forecasts.
Langdon said on arrival in New South Wales 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]."