The New Zealand jet boat marathon is underway in Christchurch, and there is a "quiet" revolution going on in the sport.
Traditionally, jet boats and big-block V8 engines go hand in hand - their sound is unmistakable.
And while there are still plenty of them at this week's national jet boat marathon, there are four entries that are very different and a lot quieter.
They are flying machines, powered by a gas turbine engine straight out of a helicopter.
One of the engines belonged to US President Jimmy Carter's helicopter.
The chopper engines are affordable to run and super quick. The boats can hit 215km/h.
The four boats will be a part of a crew of boats that will race for more than 600 kilometres as they move south, with the finish at Queenstown next week.
This week's event is a forerunner to the world marathon on the very same rivers next year.
Newshub.
