With first-five Josh Fifita injured, Ruapehu moved young fullback Shaq Waara into the No10 jumper, as the home team had to sustain a second half comeback from the visitors when Kaierau moved the ball out wide.
Ruapehu's experienced players regrouped and put the match out of reach as midfielder Troy Brown and loose forward Campbell Hart, having a great season, both scored doubles.
In Senior rugby, Speirs Food Marton are in the middle of a two week break as they picked up their automatic five points for the Utiku Old Boys default to sit well clear of the chasers ahead of their official bye this Saturday.
With Black Bull Liquor Pirates also on the bye, Kelso Hunterville took centre stage as the main team when they held off a desperate Celtic at home 27-24, closing in on second place.
Taihape and Counties were the main climbers of the weekend, as Taihape were impressive in their 46-0 shutout of the Buffalo's at Memorial Park, while Counties triumphed under lights when they beat the Border Seniors 25-11 in Waverley on Friday evening.
Ruapehu made it double for their club when they won the Rochfort Park curtain raiser with Kaierau 43-7.
To remove the Utiku default completely, the WRFU will be looking to split the Senior competition into a draw consisting of a six-team championship grade and a four-team consolation grade for the second round of matches, starting in June.
Results, May 6.
Tasman Tanning Premier, Round 8.
Grand Hotel Challenge Shield - Waverley Harvesting Border 35 (Tietie Tuimauga 2, Angus Middleton, Tom Symes, Lindsay Horrocks tries; Nick Harding 4 con, Harry Symes con) bt Settlers Honey Ngamatapouri 13 (Jim Seruwalu try, Te Tua Kemp 2 pen, con). HT: 14-3.
Black Bull Liquor Pirates 76 (Fa'alele Iosua 3, Junior Ainea 2, Romeo Tiatia 2, Tafulu Isaako, Fa'amanu Pulemagafa, Denning Tyrell, Aperagmo Fiu, Raymond Epati tries; Ainea 8 con) bt Harvey Round Motors Ratana 17 (Shaquille Docherty, Alan Penetito tries, penalty try). HT: 38-10.
Dave Hoskin Carriers Marist 26 (Sean Brown, Sam Madams, Luke Foster tries, Mitchell Millar 3 pen, con) bt PGG Wrightson/Balance Taihape 23 (Hamish Bennett, Jack Kinder tries, Dane Whale 3 pen, 2 con). HT: 15-6.
McCarthy's Transport Ruapehu 43 (Troy Brown 2, Campbell Hart 2, Matthew Clark, Shaquille Waara, Fraser Hammond tries; Cruz Pene 4 con) bt Wanganui Car Centre Kaierau 20 (Matt Ashworth, Lafaele Malo tries; Rhys Wylie 2 pen, 2 con). HT: 19-7.
Bye: Utiku OB.
Senior, Round 8.
At Dallison Park: Counties bt Border 25-11. HT: 10-3.
At Hunterville: Kelso Hunterville bt Celtic 27-24. HT: 11-7.
At Memorial Park: Taihape bt Buffalo's 46-0. HT: 19-0.
At Rochfort Park: Ruapehu bt Kaierau 43-7. HT: 19-7.
Speirs Food Marton bt Utiku OB by default.
Bye: Black Bull Liquor Pirates.