"We thought we'd become hippies and live on a commune but we quickly realised that it wasn't going to be much fun for us," he recalls.
"I decided to stop work and see what happens. I started making a great big concrete boat but after about two years I was going batty because there was no reason to get out of bed. It took me another two years to really get cracking again. I went back and started a new business. That was the worst part of my life as I nearly went nuts through having nothing to do. I'm 73 years old next month but there's no way I'll ever retire again," he says.
"I need the stimulus of the amphibians and the farm, so Serious Fun is really about keeping one's self alive."
A proud Kiwi whose descendants were reportedly the 11th European family to settle in colonial New Zealand, Gibbs left New Zealand in 1997 in order to further the development of his ambitious amphibians. However, he returns home every Christmas to spend the summer at his expansive Kaipara Harbour farm, which is home not only to his very own full-scale wild west town but also a huge collection of site-specific artworks by the likes of Anish Kapoor and Richard Serra.
"New Zealanders are the biggest travellers in the world," says Gibbs, who is based for most of the year at his exclusive Thames-side apartment. "We're the most geographically isolated people in the world so naturally we compensate that by travelling."
A founding member of the Act Party, living in London has allowed Gibbs to distance himself from New Zealand's current political landscape. "When things aren't what you would like them to be, it's quite good to not be there," he says with a wry laugh.
"When you live in someone else's country, you don't have to feel responsible for what they do and it doesn't get to me as much as it does when I'm in New Zealand."
A strong advocate of Rogernomics even three decades on, he is unrepentant about his role in the restructuring and selling off of Telecom New Zealand and the Forestry Commission in the late 80s. "The performance of Telecom in the 90s was stunning by world standards," says Gibbs, who believes that the figures speak for themselves.
"Everybody should know that in their guts because communism just fell over out of its own rottenness, it wasn't beaten at war," he says, citing the drastically reduced workforces at both the Forestry Commission and Telecom.
"New Zealanders don't seem to have noticed that and are still backing this idea of the lovely government owning these businesses and saving us from all the foreigners," he continues. "That sort of stuff makes me mad as it's just typically negative New Zealand thinking.
"It was Helen Clark who managed to convince New Zealanders that black is white. The privatisation programme was fantastic in New Zealand and productivity grew faster there than in any other decade in history. But the story that Helen Clark managed to get accepted was that it was a disaster and that everything Roger Douglas did destroyed the country. Frankly, that kind of negative nonsense is what I find least attractive about New Zealand nowadays because it's become so endemic."
He points to the example of his adopted homeland, which in just over a century has been reduced from a leading industrial power to a glorified tourist destination. "Everything here is owned by foreigners," he says.
"The locals can work for the foreigners but that's not where all the thinking is done or where the breakthroughs come from. They're made in Germany or somewhere else and that's tragic. The British all know that. Even all the cabbies who vote Labour say that Maggie Thatcher saved us. They don't say that about Roger Douglas and he did the same job. But for some reason, New Zealanders have hung on to socialism and are opposing the idea of selling off these jolly power stations in an emotionally crazy way as if there's no understanding of how bad state ownership is."
A self-styled "bush engineer", Gibbs has always had a penchant for fast cars and other big boys' toys. Having completed three quarters of an engineering degree at Victoria University before switching to Economics, he prematurely attempted to build New Zealand's first car, the Anziel Nova, in the late 60s.
"I've built various boats and cars over the years and over the last 20 years I've been trying to make a combination of both," he notes.
Boasting glowing reviews from Top Gear magazine and the subject of a record-breaking English Channel crossing, the Aquada was launched with considerable fanfare in 2004.
However, Gibbs has never sold a single vehicle, withdrawing them from sale after a fellow entrepreneur's had to be rescued after attempting to travel from Land's End to the Scilly Isles only to be caught in a rip and dragged halfway to France. "I basically decided that it wasn't the right product for the average person. It was frankly too vulnerable," says Gibbs.
"The product itself worked but people are trained to drive a car, which goes exactly where you put it if you turn the wheel in a certain direction. But the idea of selling someone a car that they can drive anywhere in the world on water when they don't know anything about it, I very quickly found to be a dangerous thing."
Not dissuaded by those setbacks, Gibbs and Neil Jenkins, his partner in Gibbs Technologies, have since turned their attention to creating a new range of more practical sports vehicles.
Set to launch in the next few months, it includes quad-bike/jet-ski hybrid the Quadski, which he is depicted riding upon on Serious Fun's cover. There's also military-style SUV the Humdinga, which is apparently "great off-road, fantastic in the water and can go 85 miles an hour (136km/h) down the motorway," and the Phibian, a 30-foot-long (9m) amphibious truck, which is intended mostly for rescue purposes.
"The world today is a very dangerous place to be a manufacturer, especially in America with product liability," he says. "Fortunately, it doesn't apply in New Zealand because we've got Accident Compensation so you can't sue somebody for hurting or killing you.
"But it's a colossal industry in America and the risks are huge when you're making any new product and that'll still be true for the Humdinga, Quadski and the Phibian but they're more readily understood. They're basically a cross between a personal water craft and an all-terrain vehicle and people have used both of those things in the past."
