Yanchep fired on five quick goals before Warwick Greenwood hit back to be two points down at quarter-time.
Warwick Greenwood kicked ahead in the second to be seven goals up at the main break before the Red Hawks cut that margin to three goals at three quarter-time.
Yanchep’s Brad Trpchev kicked a 60m torpedo goal after the final siren to end the game with nine straight goals.
Yanchep play Queens Park this Sunday in the preliminary final at Robinson Reserve at 2.30pm. In the division two first semi-final, Queens Park 8.18 (66) defeated Warwick Greenwood 7.11 (53).