Stuart Billington has been fined $2000 and ordered to pay reparation of $750 to the victim.
The jet skier was making a u-turn towards a boat ramp at Pukete when he was struck by the power boat.
He was thrown into the water and suffered internal injuries.
The court heard that at the time of the collision the boat was travelling between 20 and 25 knots, when safe practice and navigation safety regulations required a five knot speed.
