They are watching the Oxbow Adventures Sprint Tec four-seater, the only one of its kind in the world, perform some practice runs before it competes today in the fifth round of the New Zealand jet sprint championships at the recently finished aqua track.
Built by Peter Caughey, holder of six world and seven New Zealand jet-sprint titles, the boat is powered by a 6.2-litre Chev Corvette LS3 engine.
Longer than most jet-sprint boats, at 4.4m, to accommodate the two back-seat passengers, it has a deep V-shaped hull, with three fins to aid its turning ability.
After a demonically fast spin in it with track builder and double world jet sprint series champion Chris Munro - approaching the 120m long and 60m wide track's corners at 120kmh - I could breathlessly confirm Caughey has done a superb job.
Oxbow Adventures operations manager David Richmond laughed in agreement.
''He knows how to build a boat.''
Commercially viable because of its ability to carry three paying passengers at a time, the boat runs on petrol and its 17-litre tank allows it to make about five sets of runs before it needs refuelling.
At 600hp (400kW), it is a minnow compared with the super boats which can boast up to 1500hp, but it is jaw-dropping enough as far as this reporter is concerned.
''You just want it to go all day and to have enough grunt to have a good time but not enough to cart-wheel you through a paddock,'' Richmond said.
The boat will be put through its paces today by Munro, with Lloyd Ferguson navigating.
They will be competing against about 25 North Island competitors, six South Islanders and a sole Australian. Queenstown-based Munro has co-organised the event with friend Maria Scammell and is pleased to finally have a permanent course so close to home.
''We don't have anything else like this in the South Island,'' he said.
The event features three classes. The country's top super boats can run unlimited engines and there will be at least one 1500hp monster on the water. The international group A boats range from around 600 to 680hp, while the lites class features the ''entry level'' 550hp racers.
The drivers race one at a time, against the clock, through a course they were given to familiarise themselves with several weeks ago.
''If you can't remember, you can't give 100%, so you definitely try to memorise it,'' Munro said.
The navigators may give directions via an intercom, if they have it, or use hand signals, which are not drowned out by the boat's deafening engines.
There will be four practice rounds before the boats are whittled down to the final three after a series of elimination runs.
Gates open at the aqua track (995 Wanaka Luggate Highway) at 11am. Spectators are asked not to bring any glass.
