Out-half Tadhg Bennett tallied up 18 points as Shannon got the New Year off to the best possible start with a bonus point win over Blackrock College at Coonagh.
The result is a hugely significant one for Shannon, who were bottom of the pile before Christmas.
Now, after their second successive league win, they are up to fifth in the Division 1A table, level on 15 points with fourth-placed Young Munster.
Blackrock took a tenth minute lead when influential out-half Rob Keogh touched down out wide after a good lineout drive from the forwards and some quick hands from the backs.
But Shannon took only seven minutes to respond and they did so in style. Following five phases of play, Bennett got in at the corner and he added a superb conversion from the touchline.
His half-back partner Paul Rowley grabbed Shannon's second try after 25 minutes, scoring to the left of the posts after tapping a penalty. Bennett again supplying the extras.
Keogh then missed a penalty at the other end, but 'Rock were beginning to take the game to the Limerick side.
They were rewarded eight minutes before the interval when powerful centre Brendan Macken slipped through the defence for a try that Keogh converted, leaving just two points between the sides.
Shannon hit back though, registering their third try on the cusp of half-time. Bennett kicked a penalty to touch near the corner. Team captain Fergal Walsh won the lineout and prop Les Hogan was driven over for a try which Bennett converted.
21-12 ahead after a most entertaining first half, Shannon kicked on courtesy of a Bennett penalty and a try from experienced flanker Colm McMahon, who pounced on a loose ball near the line to dive over and score.
That came in the 53rd minute and with Bennett converting, Blackrock were suddenly 31-12 behind and with the rain beginning to pour down.
Flanker Barry Kelly closed the gap with the visitors' third try, and Keogh succeeded with the conversion and a 63rd minute penalty.
But the final say went to Shannon whose fifth converted try was scored by centre Marcus O'Driscoll, a first cousin of Ireland captain Brian O'Driscoll. He scooped up a dropped pass as 'Rock tried to attack from deep and cantered over for the game's eighth and final try.
Referee: Simon McDowell (IRFU)