At no stage did Otago appear to be in trouble against a Tasman side which looked a spent force early in the match.
The home side scored all its points in the first half, cut out the errors that had plagued its game and put up a blanket of defence that was far too good for the Tasman side.
Rain fell in the second half, turning the match into a bit of a lottery, while a steady stream of substitutions also impeded the flow of the game.
Tasman struggled to get back into the game after it went behind, and goalkicker Andrew Goodman did not have a single attempt in the whole 80 minutes.
Strength in the set-piece is important in wet conditions, and Otago was right on the money.
Its line-outs were strong, and though the scrums were a mess, Otago was assured on its feed.
The home team won seven line-outs against the throw and it was also a constant threat at the breakdown.
No 8 Paul Grant had his best game in the Otago jersey, showing strength off the back of the scrum and making some fine hits on defence.
With Adam Thomson showing why he is an All Black, the Otago loose forwards grabbed a bucketful of turnovers, which knocked Tasman's hopes.
Tasman has now been held scoreless for 160 minutes of rugby, though it may have felt aggrieved when winger Lucky Mulipola went over in the corner after 30 minutes.
Mulipola, whose disciplinary issues led to his leaving Otago on loan, was ruled by referee Jonathon White to have been held, but it was touch and go whether his momentum was stopped.
That decision was critical, as a try would have given Tasman some confidence.
Otago made a sound start to the game, getting its first try after just 11 minutes.
Winger Andrew Parata made a fine break which was carried on by centre Aaron Bancroft.
A great ball from hooker Peter Mirrielees found prop Ben Nolan, who steamed over from 10m out to score his first try for Otago.
Glenn Dickson had earlier opened the scoring with a penalty and he added two more as Otago streaked away to a 14-0 lead after 25 minutes.
The home side added another try when Michael Witt, on for an injured Dickson, put through a fine grubber kick and Bancroft was there to dot the ball down.
Witt had a mixed day, showing some nice touches but taking poor options at times, while Bancroft was good on his feet.
The home forward pack dominated, with the front row especially playing well.
Mulipola enjoyed his return to Carisbrook but there were few stars for Tasman, which is labouring in the home straight of the competition.
