Jet ski rider who slammed into official's boat faces trial

A man accused of crashing his jet ski into a marine officer's boat after being pulled over for speeding is facing trial in the Adelaide Magistrates Court.

Jack Mouhalos, 53, pleaded guilty to speeding on his jet ski in waters off Henley Beach on December 26 last year.

He has contested a charge of operating a vessel without due care and now faces a trial.

The court heard a patrol marine officer with the Transport Department noticed Mouhalos was travelling at a speed of up to 15 knots on a black jet ski, well above the speed limit of four knots within 200 metres of the foreshore.

The officer, David Mattner, told the court the conditions were "choppy" and when he waved down Mouhalos and spoke to him their vessels drifted about 15 metres apart.

He said Mouhalos' jet ski was slowly turning in the wind, and he turned the jet ski and accelerated at the same time.

"My vessel was getting blown away from his," Mr Mattner said.

"He was trying to ask me some questions then he just hit the throttle and his jet ski turned left.

"So from about 15 metres away he accelerated quickly and slammed into the back of my boat."

Mr Mattner told the court the impact caused significant damage to both vessels.

"I could see a big football sized hole in the front of his [jet ski] and I saw a tear in the sponson of my boat."

Mr Mattner said he was standing on the back of his patrol boat at the time, and saw Mouhalos' arms "shoot out" when he accelerated.

Magistrate Sue O'Connor is expected to reserve her decision on verdict.