Shortly after throwing the net and lifejacket back into the water, realising it was just for fishing, the owners of the floater turned up.
There were five of them in a 14-foot fibreglass boat, waving obscenities and making aggressive signals, Mr Hardy said.
As he motored away in his 12-foot aluminum dinghy, the men in the boat chased him.
"They dropped three off at Matakana Island, which made their boat a lot lighter and then chased me - they were 100m behind me for half an hour trying to catch up."
The boats were travelling in excess of 20-25 knots per hour, Mr Hardy said.
"They were yelling at me though it was pretty hard to hear over the sound of motors. They were waving their arms and making gestures at me - it was clear they wanted to get me."
The men were "pretty big" and Mr Hardy, alone in his boat, was "pretty bloody scared."
"I didn't want to become a boating statistic, with my boat upturned and me drowned."
On the phone to police during the chase Mr Hardy said they asked him if he could see any weapons.
"It's a fishing boat, there will be knives and gaffs. I said to police, one of us is going to run out of petrol soon."
When the other boat's engine died, Mr Hardy said it felt like a little bit of justice. He motored quickly to Tanner Point boat ramp where police officers were waiting for him.
"If this could happen to me it could happen again. I just feel like it is my duty to make it known."
A police spokewoman said the boat that caused "disorder in the water" had vanished.
After taking Mr Hardy's statement the police investigation into what happened had stalled.
"The people on the boat are unknown... Police don't know where the boat has gone and there is no way of tracing the boat," the spokeswoman said.
Fisheries Tauranga district compliance manager Brendon Mikkelsen said net floats needed to be named, so if they were a hazard or breaking the rules the owners could be contacted.
He said there were also rules about the size and location of nets but without further information on the net float itself, the incident in Tauranga Harbour was a matter for police.
Police advice
If anyone found themselves in a similar situation police advised they call 111, head to the nearest accessible landmark and wait for police help.
"Police will do what they can to identify the parties involved and follow the investigation until its conclusion," a police spokeswoman says.