The message, echoed by Lake Dunstan harbourmaster Shane Hitchcock and police, came after an incident during the weekend in which a boat towing a wakeboarder got too close to rowers and a paddleboarder.
While no-one was tipped out of or off their vessel, they were worried enough to contact police, who referred the complaint to Mr Hitchcock.
He gave the boatie a warning but could have issued him with a $300 fine.
While issues such as this did not come up often in his patch, with the warmer weather attracting more people to the lake, it was a timely reminder to respect other users, he said.
''There's a lot more diverse craft on the lake these days; rowers, paddleboarders, kids on lilos, right up to large outboard boats and wakeboarding boats which are designed to put out a wake ... they're the ones going to affect other users.''
Dunstan Arm Rowing Club president Jacqui van Dam said some boat users did not slow down near rowers.
''If they just slow down a bit the boat wash wouldn't be so severe and sometimes I wonder if they even see us ... it's always the cowboys that ruin it for everybody.
''We would like them to be a bit more cautious. We're all there for the same reason - to have fun - but they have to realise that when you're in a little boat, you can get tipped out easily.''
Mr Hitchcock said being tipped out could be serious.
''The lake temperature is around 18 which is not that warm ... it could have serious implications if people are tipped out.
''The shock factor could bring on medical issues.
''Nobody wants to be tipped out in the middle of the lake'' which was one reason there was a nationwide push among harbourmasters to make the wearing of life jackets compulsory, he said.
The rules
Under Maritime New Zealand rules, vessel speed must not exceed five knots (about 9kmh) within 50m of any other vessel, raft or swimmer.
Lake Dunstan Harbourmaster Shane Hitchcock said it was often hard to tell whether a boat was travelling at or below five knots so a good rule of thumb was to look at whether or not the boat was creating any wake.
''Five knots is where your wake does not disturb anybody else.''
