Government cuts to Adult and Community Education will directly affect safety on the water, the Coastguard says.
About 75% of the approximately 10,000 adults a year who enrol in Coastguard courses complete either the Boatmaster Certificate, Day Skipper or VHF Marine Radio courses.
The three courses will not be funded from next year.
Coastguard boating education general manager Mark Bright says reduced access to the courses will have an effect on safety on the water.
Some education providers have indicated they will continue to run courses on a user-pays basis, Mr Bright says, but the increased cost will be a deterrent for many people.
Maritime New Zealand spokesperson Jim Lott says anything that reduced the number of people attending the voluntary courses will not be good for safety.