Harbour's big pack made light work of Alhambra-Union at Watson Park this afternoon, setting up a 38-12 victory.
Loose forward trio Hadleigh May, Charles Elton and Ratu Dawai got plenty of go forward while lock Ben Whale provided plenty of ball.
Out wide Iloa Lihau was useful in his 50th game for the premier side and centre Aleki Morris was solid.
In other matches, Southern beat Dunedin 40-17 at Bathgate Park. Kaikorai posted its opening win - a 34-17 victory over Green Island at Miller Park.
Pirates beat Zingari-Richmond 26-23 in a thriller at Hancock Park and Taieri prevailed 42-29 against University A at Peter Johnstone Park.
ODT rugby columnist Paul Dwyer speaks with Southern captain Tei Walden after the team's 40-17 victory over Dunedin.