More good passes set up Ezra Malo and fellow debutant Justin Baty having a crack, then from another ruck Robinson took the pop pass into the hole to score a similar try to the previous.
Taking a 5m scrum for a penalty, Kaierau then drove off co-captain Joe Edwards, and prop Faith Ezra was there to score under the heap for 22-0 approaching halftime.
Ruapehū had hoped the breeze could get them some momentum, but the home side scored first after the break after an attacking scrum, where they used Baty on the cut towards the posts, and then hooker Jack van Bussel took the ruck pass to drive over.
The visitors were bringing some fresh faces in their lineup, notably a new first-five/halfback combination in Keaton Norling and Oli Keast, while former Steelform Whanganui captain Roman Tutauha made his club rugby return on the bench, as did a blast-from-the-past in former representative lock Nick Cranston.
Despite making territory, they couldn't break through and it seemed Kaierau would make it a shutout when Whanganui lock Matt Ashworth, playing off the bench after a leg injury during the week, offloaded for second-five Dillon Adrole to dash over 60m under the posts nearing fulltime.
However, the mountain men dug deep, and when a missed touch-finder presented one last opportunity, they spread to both sides of the field, leading to Cranston offloading for reserve back Jonty Curtis to score in the corner.
It was a Whale family celebration up in the Waitotara Valley as Byford's Readimix Taihape signalled their early intentions with a 52-7 hammering of Settlers Honey Ngamatapouri.
Returning home to play alongside his brothers Dane and Luke, while father Kerry has rejoined the Premier coaching staff under Tom Wells, former Otago B hooker Ben Whale scored a hat trick of tries.
Dane Whale converted six of the eight tries scored by the visitors, making their longest away trip of the season, while also dotting down were fellow 2020 Whanganui reps Matt Brown and Tyler Rogers-Holden.
Taihape's other tries came from Beau Walker, Tyrese Payne and Tiari Mumby, returning to the spot where he had a couple of altercations with the home team last season.
Ngamatapouri, who have to do without Whanganui regular Samu Kubunavanua this season because of shoulder surgery, got their converted try through Joeli Tamantyara.
The early contenders are beginning to emerge in the Tasman Tanning Senior competition, as there are four undefeated teams left after week 2.
The rematch of last year's final between champions Harvey Round Motors Ratana and Ali Arc Logistics-DNA Kennels Marist Celtic was expected to be another close tussle, but the Stihl Shop Wanganui Challenge Shield holders were dominant at Spriggens Park - winning 30-3 to continue their unbeaten run from 2020.
Kelso Hunterville locked in their top-4 spot on the racecourse grounds, beating Black Bull Liquor Pirates 34-13, while at the same time Bennett's Taihape confirmed it would no Marist success on the club's Old Timers Day by just holding off the Buffalo's 19-12.
Gemini Pepper Construction Kaierau set the ball rolling for their Premiers at the Country Club with a 33-21 win over a competitive Ruapehū, while up in Waverley, the Border Seniors had the park to themselves and pleased the home fans with a 25-5 win over Speirs Food Marton.
Utiku Old Boys continue to lead the table after they went on the road to overrun McCrea Scanning Counties 43-3 at McNab Domain.
Results, April 24
Tasman Tanning Premier, Week 1.
Grand Hotel Challenge Shield – Waverley Harvesting Border 39 (Angus Middleton 2, Vereneki Tikoisolomone 2, Kieran Hussey, Semi Vodosese tries; Nick Harding pen, 3 con) bt Dave Hoskin Carriers Marist 10 (Ashton Coates, Jack Yarrall tries). HT: 34-0.
Wanganui Car Centre Kaierau 36 (Dylan Bowater, Jack van Bussel, Faatuatua Ezra, Dillon Adrole, Ethan Robinson tries; Robinson pen, 4 con) bt McCarthy Transport Ruapehū 5 (Jonty Curtis try). HT: 22-0.
Byford's Readimix Taihape 52 (Ben Whale 3, Tyler Rogers-Holden, Matt Brown, Tiari Mumby, Beau Walker, Tyrese Payne tries; Dane Whale 6 con) bt Settlers Honey Ngamatapouri 7 (Joeli Tamantyara try; Brook Tremayne con). HT: 31-7.
Senior, Week 2.
At Spriggens Park (Stihl Shop Wanganui Challenge Shield): Harvey Round Motors Ratana bt Ali Arc Logistics-DNA Kennels Marist Celtic 30-3.
At Racecourse: Kelso Hunterville bt Black Bull Liquor Pirates 34-13. HT: 24-5.
At Racecourse: Bennett's Taihape bt Marist Buffalo's 19-12.
At Kaierau Country Club: Gemini Pepper Construction Kaierau bt Ruapehū 33-21.
At Dallison Park: Border bt Speirs Food Marton 25-5.
At McNab Domain: Utiku OB bt McCrea Scanning Counties 43-3. HT: 17-3.
Around the grounds
METRO: The St Johns Whanganui Metro Colts lead their seven-team MRU table after beating Dannevirke SC 38-10 at the Country Club on Saturday. Metro lost to 2020 champions Feilding Yellows 16-15 in the season opener, but rebounded last week with a 27-10 win over Feilding Old Boys-Oroua. In the five-team MRU Women's grade, Metro lost 65-10 away to Feilding Old Boys-Oroua, to follow up an 83-0 loss in their first game to defending champions Kia Toa.
