Cadets set the home side a target of 180 to win as Sean Davey top scored with 87. Keeper Daniel Maathuis posted a handy 33, while Chris Atkinson and veteran all-rounder Nick Smith took three wickets each.
The Mount Maunganui reply saw their batsmen coming and going, to and from the crease, as they were removed for 70. Captain Jono Boult produced Cadets' best bowling figures of three wickets at a cost of just 10 runs, while Kamal Bains also took three.
Cadets made the title decider when they took little time to beat Central Indians at Smallbone Park in Rotorua today.Batting first Central Indians were rolled for just 72 in the 16th over. Cadets, who will be chasing their 11th Williams Cup crown next weekend, waltzed to a nine-wicket victory.
Individual honours belonged to Cadets skipper Jono Boult, who for the second successive weekend took a six wicket bag returning 6/22, while Sean Davey took three cheap wickets. Sohel Rana was the best of the home side's batsmen with 28 runs.
Ruben Clinton (35 not out) and Fergus Lellman (30 not out) took Cadets through to contest the 2018 Williams Cup Final.
Williams Cup March 17-18
Sunday
Preliminary Final
Bayleys Central Indians 72 (S Rana 28; J Boult 6/22, S Davey 3/6) lost to Element IMF Cadets 73/1 (R Clinton 35no, F Lellman 30no)
Saturday
Major Semi-Final
Eves Realty Greerton 192/8 (P Thickpenny 54, T Renouf 22no; J Rowe 3/29, R Gosai 2/27) beat Bayleys Central Indians 134 (A Gibbs 27no, R Gosai 26, S Chandra 25; T Clout 4/32, J Tutty 3/37, J Boyd 2/11)
Minor Semi-Final
Cadets 179 (S Davey 87. D Maathuis 33; C Atkinson 3/21, N Smith 3/35, D Swan 2/22) beat Mount Maunganui 70 (J Boult 3/10, K Bains 3/15, G Singh 2/10)