Stephen Kelly touched down for the second week running as Shannon shot to the top of the AIB All-Ireland League Division One table.
Winger Kelly scored the try of the game at Castle Avenue, chipping over the top and winning the race for the touchdown.
His 25th-minute try helped the visitors towards an 11-3 half-time lead.
Shannon made certain of the points with tries from hooker Sean Cronin (44 minutes) and centre John Clogan (50) before 'Tarf hooker Niall Carson was mauled over in the 78th-minute.
In what was a repeat of the 2005/06 Division One final, Shannon took their time about seizing control but when they did, they took a firm grasp on proceedings.
The had the firepower to pick up their eleventh win in 14 league meetings with the north Dubliners, and two of their Munster contingent – full-back Mossie Lawlor and flanker Niall Ronan – played particularly well this afternoon.
'Tarf's 3-0 lead – after young out-half Ian Keatley had booted a penalty – was a short-lived one as Shannon veteran Andrew Thompson replied with a pinpoint place kick in the 19th-minute.
Shannon's 11-3 interval lead was hardly a match-winning one but the Limerick men were making the most of the chances that came their way.
Lawlor made the initial incision for Kelly's try. The Munster man retrieved a kick and was able to gain ten metres for his side. Thompson was picked out in midfield and he set Kelly free – the erstwhile Limerick Gaelic footballer showed off his footballing skills as he kicked over the cover and his searing pace saw him nab the try.
Thompson missed the conversion from out wide and a couple of missed kicks, including a drop goal attempt followed, before the AIB Club international planted a 36th-minute penalty through the posts.
Keatley replied with a penalty in the first-minute of the second period as 'Tarf looked to mount a comeback. However, three minutes later, Cronin was celebrating Shannon’s second try.
A high kick from Tadhg Bennett caused problems in the hosts' defence, with Thompson following up well, and the pacy Cronin was on hand to hack the loose ball on and score.
Again the conversion was missed but Thompson managed to add the extras to his centre partner Clogan's try. The seven-pointer was all about good work from prop Les Hogan, who stole the ball at a ruck, made a break and quick hands led to Clogan crossing the whitewash.
Keatley knocked over his third penalty of the afternoon before Andy Wood's men managed to secure a late losing bonus point. Their pack, which battled well throughout, set up a rolling maul off which Carson ploughed over.
SCORERS - Clontarf: Try: Niall Carson; Con: Ian Keatley; Pens: Ian Keatley (3). Shannon: Tries: Stephen Kelly, Sean Cronin, John Clogan; Con: Andrew Thompson; Pens: Andrew Thompson (2).
HT: Clontarf 3 Shannon 11
