The Croweaters 15.6 (96) defeated the Sandgropers 8.7 (55) as South Australia attempts to win its first title since 1995, the final year the championships were played at under 17 level.
Led by coach Darren Trevena, who coached the victorious Northern Territory Thunder team in division two of the 2002 championships, South Australia never really looked in doubt as it was in front at each break.
The experience of Heath Grundy (15 disposals, 11 marks and three goals), Ryan Griffen (25 disposals and a goal) and James McLeay (three goals) was telling as all three players were part of last year's championships.
Nick Batchelor, Toby Stribling and Angus Monfries were also stand out players and among the possession winners for South Australia.
Western Australia's Mitchell Morton teased AFL recruiting managers with his class and 24 touches, yet delighted West Coast officials with his play, as he looks certain to join the Eagles under the father-son rule as his father Noel played for Claremont in the WAFL.
Teammate Lance 'Buddy' Franklin, rated as a potential number one draftee, showed plenty to like about his game, with his athleticism a feature.
South Australia started the match strongly, booting five goals to two, which gave the Croweaters a 16-point lead at quarter-time.
Western Australia pegged the margin back to 10 points when Beau Wilkes kicked truly to open the second term, but South Australia added four goals to one for the remainder of the quarter and took a 30-point lead into the main change.
South Australia had plenty of winners in the first-half, with Stribling and Griffen gaining over 30 touches between them, while McLeay booted three goals and Grundy kicked two majors.
In a low-scoring third term, the Sandgropers managed to outscore the Croweaters, adding two goals to one, but South Australia still led by 24 points heading into three quarter-time.
South Australia booted the first four majors of the final term to ensure victory.
Western Australia: 2.2 4.2 6.4 8.7 (55)
South Australia: 5.0 9.2 10.4 15.6 (96)
Goals: Western Australia: Morton 2, Corbett-Wynne, Cox, Delmenico, Franklin, Wilkes, Wright
South Australia: Grundy 3, McLeay 3, Thomson 2, Batchelor, Griffen, Meyer, Monfries, Saunders, Sugars, Taylor
Best: Western Australia: Morton, Franklin, Hams, Bowers, Le Cras, J.Smith
South Australia: Griffen, Grundy, Batchelor, McLeay, Stribling, Monfries
