Jet-boating is a popular hobby, particularly in the South Island.

Thousands of boaties will lose unrestricted access to Canterbury's rivers unless they pay to join a private organisation, under a proposed Environment Canterbury (ECan) bylaw.

Only members of Jet Boating NZ (JBNZ) could boat freely in 29 open speed areas throughout Canterbury, under ECan's proposed Draft Navigation Safety Bylaw,

Non-members will have to apply for special dispensation to the harbourmaster to boat in those areas.

There are around 10,000 jet-boat owners New Zealand wide, with a large number in Canterbury. The Waimakariri River is the most popular jet-boating spot in the country.

Currently, there is a blanket exemption on all Canterbury rivers for anyone planning to exceed the 5 knots per hour speed limit, which includes jet-skiers and air-boaters as well as jet-boaters.

Under the proposed rule, those users would have to apply for a permit, or pay to join JBNZ.

ECan said the blanket exemption had been "abused," justifying the proposed rule change.

JBNZ, a private organisation, currently represents about 20 per cent of jet-boat owners.

Acting regional harbourmaster Ian Fox said applying for an exemption would be a simple process.

The blanket exemption currently in place was not satisfactory, he said.

"This exemption given to all boats has been abused and caused concerns and navigation safety issues. The draft, as written, would remove this general exemption for rivers in the Canterbury region.

"In the draft, JBNZ would be granted an exemption for their members on the basis that the club has an existing and constantly improving set of safety and training standards."

Veteran jet-boater Duncan Storrier, who has jet-boated for 25 years, said he had "grave concerns" about the proposal and what it meant for free access to rivers.

"Jet boating is quintessentially New Zealand. It's an iconic thing and New Zealanders have enjoyed relatively open access to the rivers up until now.

"It effectively means that 80 per cent of New Zealand's jet-boat owners lose access to their rivers," he said.

He disputed claims that JBNZ members were inherently safer, and said applying for JBNZ membership only involved signing up on its website and paying the fee.

"The reality is, you can go online and join JBNZ and go boating. To me, ECan have got it wrong in their perception that JBNZ members are safer."

The rule change caused heated discussion on a website hosted by JBNZ, with some arguing it would deter people from the popular hobby.

Some compared it to requiring motorists to join the AA to drive on a motorway.

JBNZ president David Street defended the draft bylaw, which his group supported, and said anyone could still apply for an exemption.

He acknowledged it would increase the group's membership, but it would be for the benefit of all jet-boaters.

"It will increase our membership. But more importantly, it gives a voice to jet-boaters. At the moment they haven't really got a voice when it comes to river access or safety.

"We're not representing all jet-boaters at the moment."

He said JBNZ's members were equipped with information to boat safely.

"We supply our members with an annual safety yearbook... we also put out a quarterly magazine with safety tips in it, so we would hope those sorts of things help people boat safely."