As one Otago local authority moves to make life jacket use compulsory, and others consider it, Dunedin Marine Search and Rescue chairman Martin Balch believes lack of knowledge of boating navigation rules is a more pressing safety issue.
"I would always argue for life jackets but the overriding thing that comes through is not so much [their] lack but total lack of knowledge of international collision regulations," he says.
"The big issue is knowledge of regulations and enforcement. I doubt if one day goes by on the water in popular areas without me seeing collision regulations being broken at least hourly."
During recent observations at Lake Dunstan he frequently saw boats failing to keep right, not changing direction (to the right) when on a collision course, forcing boats with right of way to change course.
"The classic I saw was a jet ski towing a skier with one on board through the Cromwell gap after dusk. They had no aft-facing observer. You often get abused if you try to correct people."
Collision risks were compounded by people not slowing down in narrow rivers with blind corners.
"The overall regulation is you can't exceed 5 knots [9.3kmh] within 200m of shore, boats displaying a diver's flag, or within 50m of any other boat or any other person swimming in water.
"But these are often amended by local regulations for jet-boats in ski lanes and narrow rivers to operate at higher speeds."
"The blatant disregard for requirement to carry suitable PFD's [personal flotation devices] for all on board means we are headed towards boat registration, and 'carrying' will be amended to 'must wear' at all times - even though existing rules and regulations are more than adequate to control boating," Mr Balch said.
The Queenstown Lakes District Council plans to introduce a bylaw to make life jacket use compulsory by the end of summer.
The QLDC announcement was made after a private jet-boat and jet ski collided on the Kawarau River, near Frankton, on Monday night, killing two men, from Lake Hayes and Queenstown, and injuring two Invercargill jet ski riders.
Neither of the dead men was wearing a life jacket.
Otago Regional Council corporate services director Wayne Scott said the issue was likely to be raised during public consultation on the review of Otago Regional Council navigation safety bylaws, due to take place before April.
"I suspect there will be debate about making it [wearing life jackets] compulsory and I'm sure there will at least be heightened awareness after recent incidents.
"Adventure boating is not confined to the QLDC area and their input will be invaluable," he said. Changes to bylaws would have to be "sensible" to cover recreational activity on waterways as diverse as Lake Waihola and Otago Harbour, he said.
The ORC administers Otago Harbour, Lake Waihola the Blue Lake at St Bathans, and waterways in the Clutha District area.
Clutha mayor Juno Hayes said Clutha District councillors would most likely support ORC moves to tighten personal flotation device bylaws.
"Personally, I would support it but can't speak for councillors. If we all adhere to a common-sense approach we would support it 100%.
"There are already rules to ensure there is one for each person on board, and they are sized to fit people on board."
Central Otago Mayor Malcolm Macpherson said the Central Otago District Council's Clutha Management Committee, comprising members of the Roxburgh, Vincent and Cromwell community boards, would meet on February 5 to review summer waterway activity.
Water traffic was up in Central Otago this summer, possibly as fewer people opted to holiday overseas, he said.
"After a review of the summer's activities, I wouldn't be surprised if we tuck in behind the QLDC and do something similar. There's a perception inland water is benign and safe, and it's nerdish to put on jackets, so close to shore.
"But we need to find ways to educate . . . and reinforce a broader safety message."
Possible options to change unsafe behaviour may be more signage around boat ramps, hand-outs detailing boating rules, or partitioning recreational areas to separate activities.
Central Otago Lake Dunstan Navigation Safety Bylaws (2006) make life jackets compulsory on boats in the area for children under 10 (on boats under 5m), those on boats operating in rough conditions or after dark, or if ordered by enforcement officers.
