Mid Canterbury struck first of the boot of Solomona Paraki but in the conditions territory was the key and an error at their own end invited south Canterbury into the red zone.
From the scrum South Canterbury swept blind and as the defenders slipped wing Liam Edwards scythed through to score in the corner.
South Canterbury had the superior kicking game to play in the right half but there was nothing superior about a wobbly cross kick except for the result, as the intended kick for the wing was taken by fullback Jared Trevathan in the middle of the park but he managed to slip through the Mid Canterbury defence for the second try.
The Hammers came charging back to have powerhouse prop Tukulua Tolu crash over and the Paraki conversion closed the gap to 12-10.
However, on the cusp of halftime a poor clearing kick from the visitors set South Canterbury up in the red zone again and the competitions top point scorers didn't let the opportunity go to waste with Timaru Tafa barging over to send South Canterbury to the break ahead 17-10.
Learning their lessons from the first 40 minutes, the second half developed into a territory battle but neither side could gain ascendancy.
The lineout was lottery all day but some quick thinking from Mid Canterbury gave them the chance they were after with a quick line out throw that caught the hosts napping and centre Ben Kitching pumped the ball deep.
Mid Canterbury rumbled the ball up and Tolu was on hand to crash over for his second.
South Canterbury looked determined to score a fourth try and make the result safe string together more than 20 phases as they pounded their way to the Mid Canterbury try line but were stopped a metre short and Mid Canterbury cleared to safety.
An error in their own 22 had the hosts with a few nervous moments but again the conditions conspired against the Hammers, coughing up possession in the hunt for a match winner.
Instead of going searching for the bonus point South Canterbury settled for the win putting the ball into to touch, but had bonus of reclaiming the Hanan Shield for the season.
South Canterbury 17 (Tafa, Trevathan, Edwards tries; Edwards con)
Mid Canterbury 15 (Tolu 2 tries; Paraki con, pen)
HT: 17-10
