When my husband and I did the Shotover Jet in Queenstown, NZ, our two children were not with us, so on our latest family trip to Sydney, I booked all of us for the Jetboat ride.
It was raining a bit when we arrived at Darling Harbour. By the time we were boarded and on our way out of the harbour, the rain was pouring hard. So even before we started making 270-deg turns, everyone was getting wet from the rain, as the ponchos that were provided were totally useless for protection. It did not help that our ponchos were ripped at the shoulder or neck seams, particularly the ones worn by my husband and two children. Their shirts inside were totally soaked afterwards!
Nonetheless, it was a lot of fun and the highlight of a rainy day.
Best bet would be to do this ride wearing quick-drying shorts and shirt, rubber slippers/flip-flops or no footwear at all! Another tip - once the driver signals that he is about to make a turn, make sure to hold on tight to the bars, otherwise you will slide hard to the side.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.