He was located by Coastguard in the water a short time later and was transported to hospital for an assessment.
Raglan Volunteer Coastguard president Wally Hawken said his organisation sent a rescue boat and jetskis to assist the rescue.
“Everyone is accounted for,” he said. “We don’t believe anyone has serious injuries.”
Hawken said the conditions in the harbour were not overly rough but that the vessel had taken on “a big wave”.
The boat had not capsized but was in strife, he said.
A witness on shore said there were ambulances parked on the wharf on Wallis St this morning.
A Hato Hone St John Ambulance spokeswoman said three ambulances went to the scene and a helicopter was initially used in the rescue.
Two patients were transported to Waikato Hospital in a moderate condition, and three patients were treated for minor injuries at the scene.
Worksafe and Maritime NZ had been notified of the incident.