Transport Minister Gerry Brownlee says it would be difficult to police a legal drinking limit law for people operating boats.
Queenstown Harbourmaster Marty Black has called for a change after two men crashed a jetboat on the Kawarau river last Friday. The men failed breath tests but police acted only once they had driven off by car.
The National Pleasure Boat Safety Forum has recommended the creation of a mandatory alcohol limit for skippers, and a testing regime.
Jetboating New Zealand, which is part of the safety forum, backs calls to close the loophole that prevents drunken skippers being prosecuted.
But Mr Brownlee told Radio New Zealand's Morning Report programme on Monday it would be too difficult to enforce a drink limit law on the water.
"It's not like on land where you can set up a stop and everybody files through it and blows into the machine ... when you're at sea it's quite different."
Jetboating New Zealand president Garth McMaster said guidelines are needed so skippers, like drivers of cars, know exactly how much they can drink before driving.