On Saturday, the creation of Pisa Moorings man Anthony Robertson had its maiden voyage on Lake Dunstan.
The "party boat" contains a spa holding about 1800 litres of water, neon lights which glow in the water, decent chilly bin space and an impressive sound system.
Mr Robertson said its conception came about a year ago, when he and friend Andrew Dawson were sitting around the table, drinking rum.
"We thought, we enjoy boat parties, and we love spa parties, so how cool would it be if we could have spa-boat parties?"
After the spiced-rum haze, he kept with the idea, beginning with only a messy sketch.
"We started from a sheet of aluminium, built the boat, and ended up with this. It’s a pontoon boat and we’ve put a spa into the hull. We just made it up as we went."
He once raced F1 tunnel boats, and worked on race boats, but they were "very different", he said.
Mr Robertson manages Pisa Moorings’ Heritage Collection Lake Resort apartments and has a building company.
The job took eight months and included trial-and-error physics lessons.
"We didn’t even know how it was going to float in the beginning."
The gas-powered pool takes about four hours to heat and can hold about 12 people.
The boat was named Sailor Jerry’s, in deference to the rum brand which helped inspire the idea.
"It’s a New Zealand first, nothing like it around. It’s a pretty cool machine, really."
Before the first official voyage Mr Robertson and friends had a trial run, which was mostly successful except for a few teething problems including catching a pole on the Pisa Moorings bridge.
Initially, he wanted the craft to be smaller, but regulations meant it had to be more than 8m so people on board were not required to wear life jackets.
He was "too scared" to add up how much the project cost.
"It was a very expensive bottle of rum in the end."
