The first swimmer home without a wetsuit, Kamper, also won the 15-19 years girls category. Birkett recorded a time of 32m58s and Edi Kamper stopped the clock at 36m04s.
While Kamper managed back-to-back titles Central Hawke's Bay Swimming Club 16-year-old Bevan Jacobs was pipped by 14 seconds in his quest to go back-to-back in the open men's 2.5km race.
Wellingtonian Ben Campbell-Macdonald, a 30-39 years entrant who was visiting Napier for Art Deco Weekend because his fiance is from the Bay, was first home in 30m02s. Like Kamper, Jacobs, said the choppy conditions prevented him from improving on his 2017 time of 28m16s.
"It was still a pretty good swim for me. I tried to pass Ben but he kept up the pace. This result has made me more determined to try a bit harder next year," Jacobs said.
He got the ideal form of consolation with the prize for the best 15-19 years male. Hawke's Bay triathlete Lachlan Cairns of Hastings was third in the open men's race with a time of 32m38s and second in Jacobs age group.
"Ben [Campbell-Macdonald] was a bit of a dark horse entry from out of town. It was good to have him here," event director Trevor Adsett said.
Adsett was thrilled with the 220 entrants.
"The whole event had a good vibe and high fives to all the swimmers and sponsors," Adsett added.
The Napier Boys' High School Red trio of Hadlee Dyer, Joe Avison and Jonty Laver won the teams title in the 2.5km race. Hawke's Bay's Vicki Moffitt backed up Adsett's pre-race prediction by winning the women's masters 60-plus title in 40m02s.
Being the eighth-placed female overall added to the significance of Moffitt's feat.
Westshore Surf Lifesaving Club 14-year-old Mahina Ross won the 1km race in 14m22s. Taupo's Cole Scott, a 15-19 years entrant, was two seconds behind Ross.
Napier's Lydia Dew won the 300m dash in 3m20s. Ella Simmons of Havelock North won the 200m kids class in 3m59s.
Thomas Mackenzie of Hastings won the 2km standup paddleboard race in 18m21s. Earl Wykes of Hastings gained title honours in the 3.5km paddleboard race with a time of 30m26s.