Queenstown Harbourmaster Marty Black says a loophole in the law means maritime agencies are powerless to prosecute drunken boaties.
A man who crashed a jetboat on the Kawerau river on Friday night was a short time later stopped by police for drink driving.
Mr Black said while it is illegal and dangerous to operate a boat while drunk, the Coastguard has no way to breath-test boaties.
He said the problem needs to be solved by central Government.
A member of the public heard a crash at the Kawerau Falls bridge at 10.45pm and saw the men, who are in their early 20s, pushing their boat off rocks before it floated downstream.
They were found by the Coastguard at the ramp and warned not to drive home because they had been drinking.
However, a vehicle was stopped on the road by police 15 minutes later and the driver failed a breath test.
Police said the driver will be charged with driving while over the legal blood alcohol limit.
