The first around the buoys with an unbroken egg won.
Mr Wilson said the turning point was around two 5knot warning buoys about 600m apart.
The first run was uneventful as the boats went in a clockwise direction.
However, on the second run one of the boats attempted to turn the buoy in the opposite direction to the lead boat, he said.
The driver realised there was going to be a collision so closed the throttle, stopping the boat. The other boat was also stopped and tried to back up but Mr Wroe and the other rider were flung into the water as the biscuit smashed into the other boat and burst from the impact, Mr Wilson said.
The impact of the biscuit hitting the Opposing boat left fibres from the ski biscuit imbedded in the hull.
Mr Wroe suffered serious injury to his abdomen, including fractured ribs and a ruptured spleen.
"It is likely that the injuries were almost instantly fatal," Mr Wilson said.
The other rider was knocked unconscious and suffered serious bruising.
Boats must travel no faster than 5knots when within 50m of another vessel, structure or person in the water or within 200m of the shore. However, in the Whirinaki Arm this is restricted to only 30m because of the width of the channel.
Following an investigation into the death, two of Mr Wroe's friends, Tony Sargison, 44, and James Worsnop, 35, were charged with operating a boat in a manner that caused danger to Mr Wroe.
Both pleaded guilty and were fined $3000 each. They were in court for today's inquest.
Dr Bain asked Mr Wilson if there was a "re-occurring theme" around these type of water deaths considering the latest deaths - Genevieve Lewis was killed by a boat while water skiing on Lake Taupo and Bishop Thompson died after being hit by by a jetski after falling from another jetski on Lake Tarawera.
It was of concern so many were dying each summer while enjoying the outdoors, Mr Wilson replied.
Dr Bain said New Zealand was a nation of people who loved the great outdoors but the time was coming when people would face more serious charges if they didn't start obeying the rules and someone got accidently killed on the water.
"The message has to get through ... the time is fast coming when some of our boaties may well face manslaughter charges for breaching regulations ... we need to ram this home ... we are a boating nation who like to do what these people were doing," he said.
"It's a real concern. The public's patience is running out. Boaties need to be aware."
Dr Bain has reserved his finding.
