There were two men and two children aged about 5 and 7, but only one man and one child were wearing lifejackets, Bradey said.
He said the jet ski was clearly over-loaded and was shocked the adults went out on the water in "choppy" conditions without lifejackets for everyone.
"Any one of them could have been swept away. If the tide had been going out the other way, we could easily be talking about at least one death," he said.
Bradey said the second rescue, about 30 minutes later, involved a couple in their 20s onboard a 4m fibreglass boat who got into difficulties while fishing in the same area.
They were stranded about 1km out in the channel, he said.
Bradey said he and his wife motored out in their 5m boat and towed the other vessel back to shore.
The conditions were still "quite choppy" with about half metre high waves, Bradey said.
The stranded couple, who were visiting from Australia, were having steering problems, he said.
"They had no lifejackets and no oars to paddle their way back to shore and it wouldn't have taken much for the boat to have tipped over.
Bradey said this couple could also count themselves lucky someone was nearby to rescue them.
"We have seen this happen many times before, and I can't understand why people haven't got the message wearing a lifejacket is essential," he said.
The Bradeys believed a competency test would ensure people were using water crafts safely.
Grant Nicholson, owner of Action Sport Direct and member of the Tauranga Jet Ski
Sport Association, said these two incidents were clearly a "recipe for disaster".
Nicholson said it would be silly for jet skiers and boaties not to wear lifejackets.
"It's the equivalent to wearing a seatbelt. But, no matter what type of craft, anyone going out onto the water should wear a lifejacket as a safety precaution," he said.
Nicholson supported the call for a user competence test but he said there needed to be a level playing field when it came to any type of water craft.
A regional council spokeswoman said whether people had a kayak, jet ski, waka, sail or power boat, they must know the rules, have the right equipment and be responsible.
Under the Navigation Safety Bylaw, jet skis were classified as boats and lifejackets had to be worn by all on board, unless the skipper had assessed the conditions and deemed it safe to remove them.
There was no requirement in Bay of Plenty region for people to wear a helmet while onboard a jet ski.
A user competency test was something the regional council would support but would need to be introduced by Maritime New Zealand, the spokeswoman said.
As at December 6 only 220 jet skis with Bay of Plenty addresses had been registered through the Auckland Transport site.
Some of rules under the new BOP Regional Council's Navigation Bylaw
People on board a vessel 6m or less must now wear a lifejacket unless the skipper, who is over the age of 15, has assessed the risk and deems it safe not to wear one.
All personal water craft (jet ski) used in Bay of Plenty waterways also need to be registered with the regional Council or other participating council.
Powered vessels over 4m, and non-powered vessels over 6m, must be named.
A moving prohibited zone is in force in Tauranga Harbour for large vessels over 500 gross tonnes. Boaties must not navigate 500m in front and 50m either side.
