While Marist were missing many chances at least they were creating some inspirational flanker Bradley Graham was used as the first hit up off the ruck and made some strong yards, while his tackling was first rate as always.
Lock Aiden Fitzgerald got through a fair bit of work, while try scoring centre Mohi Waihi had his moments early on.
Fullback Matt Neilson also added a smart five pointer when he took a seemingly innocuous looking Marist switch play and glided through the tacklers and sprinted 30m to score.
On the other side of the fence, Kaierau offered little for their representative fullback Ace Malo or halfback Josh Edwards to build on.
Having reversed yet another Round One loss, Marist backs coach Martin O'Connell was more than happy to take a scrappy four competition points.
"It's excellent for the boys, not a great performance but it was a win."
While it was a hard day to get going he was pleased the pack had done the business.
"I thought they dominated, especially in the scrum."
For Kaierau coach Keith Savell, who had only known his full lineup when a number of senior players arrived to sit on the bench after their game, he just had to let the match go and look ahead to Utiku Old Boys this Saturday.
"We were missing a few key personnel Michael Horrocks, Brendan Lawrence, the list goes on.
"But that's not an excuse, Marist played well.
"We didn't have continuity, Marist did."
After camping in Kaierau's territory, Marist finally opened them up after 11 minutes when Waihi looked for his options but spun himself into a half gap to score next to the posts.
Kaierau's flanker Joel Martin, and first five Areta Lama created a couple of chances but the visitors struggled for field position.
Finally getting some territory in the dying minutes of the half, a Malo penalty narrowed the scores.
Marist replied right after half time as second five Marek Willis made the gap but lost sight of his support, yet his loose pass was still brilliantly collected by Tihema to score.
With 10 minutes left, Neilson gave the chilly Marist supporters something to cheer about with his well taken try.
Edwards kept marshalling Kaierau to keep trying and they finally earned some reward in the last five minutes when Marist infringed on their line, resulting in a penalty try.
At Spriggens Park Dave Hoskin Carriers Marist 21 (Mohi Waihi, Matt Neilson, Grayson Tihema tries, Sean Brown 3 con) bt Wanganui Car Centre Kaierau 10 (Penalty try, Ace Malo pen, con). HT: 7-3.