Boles also finished fourth and National Silver in the 16-17 age group in the 10km race, with that contest the first step for athletes to qualify for the FINA World Championships later this year - the top five now able to move forward to the second stage of qualification.
Former John Paul College student Kane, who trains at Perth's Claremont Aquatic Centre was delighted to hear of Boles' win - the sixth year in a row Swim Rotorua have won the 5km title.
"I'm so stoked for Davey [Boles] getting out there and taking out the win and keeping it within the club [Swim Rotorua]," he said.
It's now back to the pool for Boles who is looking to make his mark at the New Zealand Age Group Championships in Wellington in March.
"It's something David should be very proud of," said Bronwen.
"He followed the plan we had come up with to the letter and it's a brilliant major title for him to have.
"For Swim Rotorua this is a great result and if David keeps working hard he's got a very successful future ahead of him. There's some amazing talent coming through at the club and we have a great club spirit right now."
In the women's field Charlotte Webby [Aquabladz New Plymouth] retained her title from last year and completed the double-double after winning the 10km yesterday after claiming both races in 2016.
Webby again proved her dominance coming home in 1h 04m 14s ahead of Sammy Winward [Waterhole, Auckland] in 1h 06m 26s and Stefannie Gillespie [Zenith, Dunedin] in 1h 06m 27s.
"I was thinking I would just go out there and sit with the field and practise sitting on people's feet and then go but I got into race mode and just went for it," Webby said.
2017 New Zealand Open Water Championships results:
Open Water 5km Results:
Men: 1. David Boles (Rotorua) 1:00.52; 2. Ben Ruback (Capital) 1:01.12; 3. Sebastien Priscott (Waterhole) 1:01.13; 4. Jordan Gadsby (Aquabladz New Plymouth) 1:02.36.2; 5. Thomas Raymond (Matamata) 1:03.12.6, 5.
Women: 1. Charlotte Webby (Aquabladz New Plymouth) 1:04.14; 2. Sammy Winward (Waterhole) 1:06.26; 3. Stefannie Gillespie (Zenith) 1:06.27; 4. Talya Harwood (Tasman) 1:06.29; 5. Claudia Ashby (Fairfield) 1:07.06, 5.