He said the other rule they had noticed being broken a lot was people parking their boats in the ski lane.
"People have to be able to get in and out of those lanes."
The coastguard had already had a number of calls to our many lakes for many reasons, said Mr Grouby.
"It's mainly been for breakdowns, we've had a couple where people have run aground in a beach area, motor troubles, and the other day we assisted a helicopter in a rescue at Hot Water Beach at Lake Tarawera.
"In general though, people are out there wanting to have fun," he said.
Bay of Plenty Regional Council senior maritime officer Ross Powell said overall, there had been an improvement in behaviour of people on the lakes this holiday period compared to previous summers.
"People need to be more vigilant with ensuring that they have enough appropriate life-jackets for every person on board their vessel.
"With the influx of holiday visitors over the summer, it is a timely reminder for everyone to follow the appropriate directions for safe use of the designated ski lanes. These directions are clearly outlined on signs located at boat ramps and at the ski lane locations. Following these directions will ensure safe and enjoyable use of these areas for all," he said.
Taupo harbourmaster Philip King said they had been pleased with the behaviour of boaties on Lake Taupo so far.
"We have had a couple of boats that have sunk, but in both cases the skippers managed themselves really well.
"Any messages we would say would be continue wearing lifejackets and keep a watchful eye on the weather.
"There are a lot of people on the water at the moment and what we especially want to enforce is being aware of your speed and close proximity of others," he said.
Whakatane Coastguard spokesman Jim Williamson said Whakatane boaties has been well behaved this summer to date.
"Everything has been running smoothly, I would just encourage people to watch the bar crossings and report before and after crossing the bars. But everybody is pretty well behaved at the moment," he said.
Five simple rules to help you stay safe on the water:
1. Life-Jackets: Take them - Wear them. Boats, especially ones under 6m in length, can sink very quickly. Wearing a life-jacket increases your survival time in the water.
2. Skipper Responsibility: The skipper is responsible for the safety of everyone on board and for the safe operation of the boat. Stay within the limits of your vessel and your experience.
3. Communications: Take two separate waterproof ways of communicating so we can help you if you get into difficulties.
4. Marine Weather: New Zealand's weather can be highly unpredictable. Check the local marine weather forecast before you go and expect both weather and sea state changes.
5. Avoid Alcohol: Safe boating and alcohol do not mix. Things can change quickly on the water. You need to stay alert and aware.
Source: www.coastguard.nz