Napier man Paul Roche was on one of the boats with his family and, like the group on the second boat, had cut their engines as they were inside the 200m buoys which indicate the 5 knot speed zone.
They had spotted the sole orca about noon, not far from shore where it appeared to be playing with a stingray.
"Then we saw this boat coming at full speed," Mr Roche said.
"I thought 'far out' that's moving pretty fast. It ran it over."
The group saw blood coming from the orca as it began swimming off toward Westshore.
They followed it for about half an hour.
"It was in trouble and didn't look good, blood was running out like a tap."
Mr Roche said they had waved out to the speeding boat and it returned to the spot before taking off again toward the port breakwater.
He said while trailing the orca to Westshore they were called out to by a man who asked that if they saw his kontiki long-line could they retrieve it for him. He believed it had been severed by the same boat.
"We weren't too sure what to do or who to call," Mr Roche said, adding that in the end they called the Aquarium of New Zealand for advice.
They were told that boat strikes on surfacing whales did happen from time to time and there was little that could be done.
"But we were surprised at the speed the boat was going inside the buoys. If they had been going inside the speed limit it could have been avoided."
He said the incident had left his children upset and he himself was annoyed that the boat had been exceeding the inshore limit.
"I read about the jetskiers speeding inside the buoys and then we saw this. It's not good."
Hawke's Bay Regional Council harbourmaster Phil Norman said powerboats "frequently" flouted inshore speed limits along the Hardinge Rd foreshore as the inner harbour area.
"Part of it may be ignorance, that they just don't know about the limits, but a lot of people simply don't care."
He said signs about the limits were clearly in place at boat launching areas and authorities would be upping their surveillance and issuing infringement notices to offenders.
Mr Roche said he would be speaking to Mr Norman.