Banks subbed on and uncorked a spectacular 60m solo try without ever appearing to move out of second gear. He was aided and abetted by a superb hat-trick by sharp right wing Viliami Lolohea.
His third try was almost gifted when North Harbour committed rugby hara-kiri in front of their tryline and Lolohea stripped his opposite Tevita Li of the ball.
The first half was indeed "a half of two halves," as TV comments man Richard Turner exclaimed. Tasman sprinted out of the blocks with tries to veteran halfback Jimmy Cowan, from an 8-9 move on a retreating scrum, and Lolohea.
But North Harbour's committed and effective work in the pack, where men like prop Nic Mayhew and lock Gerard Tuioti-Mariner shone, started to pay dividends. Wing Nafi Tuitavake scored a cracking try after 15 phases from an inside ball by his fullback Matt McGahan. It was 14-13 at the break. Game on. Or so it seemed.
Harbour second five Michael Little continues to go from strength to strength, his work at the breakdown especially solid, and he scored a nice try, combining with midfield partner Matt Vaega.
Tasman must refocus to host Auckland on Sunday in Blenheim, while North Harbour welcomes Canterbury on the same day, 12 months after upsetting them in Albany.
Tasman 39 (Viliami Lolohea 3, Jimmy Cowan, Marty Banks, Mitchell Scott tries; Trent Renata 2 con, Banks con, pen) North Harbour 20 (Nafi Tuitavake, Michael Little tries; Daniel Halangahu con, 2 pen, Matt McGahan con) Halftime: 14-13