The under-15s won by 15 runs against Perth at Lark Hill while the under-17s rolled minor premiers Joondalup at Iluka by 38 runs to show the future is bright at the Mariners.
Back-to-back premierships are one game away for the under-15s who batted first and made 189. Wesley Steele opened the batting and his 63 at a slick clip set up the effort with the bat.
Middle-order contributions from Jaxon Standing (31) and Isaac Mitchell (30) helped to boost the total up to a target score of more than three runs an over for the Demons.
In a man-of-the match display, Steele removed three of the visitors’ top four batsmen to take 3-22.
Rockingham-Mandurah kept their nerve throughout the bowling performance as Perth rallied with 40-plus run stands for the first and fifth wickets. Griffin Polglaze had the figures with 4-30 and Danial Sudden’s 2-35 took his season tally to 25 wickets.
The under-17s will enter the grand final at the top of their game after they saw off the Centurions last Saturday.
Batting first, the Mariners made a telling score of 200.
Aaron Burrage top-scored with 50 and combined with captain Jake Eardley-Wilmot (23) for 75 runs for the second wicket. Matthew Edwards picked Joondalup’s bowlers apart for 45 from 54 balls and the side went into the lunch break on a high.
They had Joondalup at 1-0, 5-54 and 7-72 to knock the game on its head. Joondalup eventually succumbed for 162 with Lachlan Pratt snaring 4-47.
The under-15s will play Joondalup in the decider, the Centurions just eclipsing the Mariners on the ladder after the regular season.
The under-17s meet South Perth, who were one of the side’s victims in their current winning streak of six matches.