The ban had been welcomed by the community and largely accepted by students, she said.
Issues arising from cellphone use included students upset and classes disrupted by ''nasty, slanderous'' messages; students using phones to organise, record and upload fights, usually to Instagram; and staff time consumed by dealing with the fallout from social media posts.
She now had far fewer incidents to deal with and most of those were ''low level''.
Students previously on their phones at lunchtime were now playing cards or board games with their peers.
Some had complained there wasn't enough to do so, with teachers already busy, Painting-Davis was applying for funding to start up extra lunchtime activities. Prefects were planning to organise trivia and karaoke sessions.
Other changes included a comeback of watches because students could no longer rely on phones to check the time.
Student Otulea Latu, 15, said he was socialising more and filling break time by playing cards and games.
''There's a lot less fighting going on. I get more done now, there's less distraction.''
A ban was first mooted by the Board of Trustees in 2019 but at that time the school opted instead to bar phone use during class but allow them during breaks.
That hadn't worked, Painting-Davis said.
One of the concerns raised by parents ahead of the ban was that they relied on cellphones to contact their children.
However, students could still take phones to and from school if they handed them in during the day.
Parents who needed to contact their children during the day could ring the school office, as they did before mobile phones were invented.
All Year 9-13 students had a Chromebook which was connected to the school server with inappropriate sites blocked.
Teachers were required to lead by example by not having phones in class.
Martin Cocker, the head of online safety organisation Netsafe, said cellphone bans weren't his preferred method for controlling cyberbullying.
''Our programme is designed to allow heavy use of technology within the school while managing the risks,'' he said.
''Ultimately what we are trying to do is not have schools having to ban phones ... but every school has to come up with an approach that fits the challenges they are facing, and I accept sometimes it's the only way to get on top of a problem.''
Northland College in Kaikohe has since followed Bay of Islands College by banning phones from May 12. Other schools with cellphone bans include Springbank School, Huanui College and Kamo High.