Cameras are to be put up at the entrance to Tory Channel to monitor boating behaviour.
A report to the Marlborough District Council noted 35 reports of excessive speed by boaties in December and 28 last month.
Waikawa Boating Club commodore Mark Gibbs said no-one knew of the plan and some boaties would be upset. He said it was strange the cameras would be placed in an area that required great caution.
Marlborough Deputy Harbour Master Luke Grogan said there were plans to place the cameras elsewhere in the Sounds.
The three cameras will also gather data on weather.