If anyone’s come up with an image more cinematic than a matchstick-sized man riding a tsunami of a wave, I’ve yet to see it. And Ride the Wave’s matchstick man ratchets up the tension by being a 14-year-old boy: Ben Larg, a Scottish junior surfing champion based on the Hebridean island of Tiree. Normally, big-wave surfing documentaries focus on lantern-jawed, seasoned watermen, but Martyn Robertson’s film has an interestingly vulnerable edge by focusing on the stripling Larg’s desire to tackle Aileen’s and Mullaghmore, two of the cold-water breaks on Ireland’s west coast – and how his parents manage their stress levels accordingly.

One minute Larg is a blond-bobbed grommet, with more than a passing resemblance to the late Dogtowner Jay Adams, crying after flunking his heats at international competitions. Half an hour into the film, he’s suddenly a bum-fluffed teenager who’s sizing up the Gaelic big-wave spots, notably the menacing Aileen’s which is capable of holding 50ft waves that wash you towards a scree field underneath 700ft shale cliffs. It’s the latest instalment of an old story: how troubled surfers throw themselves into the waves to wash off emotional turmoil on land. On Tiree, his parents are immigrants from inland, and Larg is heavily bullied to the point where they pull him and his siblings out of school.

While they shield him educationally, putting him into an internet school, they practise helicopter parenting in the truest sense: by sanctioning the possibility of Larg being airlifted off the rubble at Aileen’s if he messes up his takeoff. But good on them for promoting responsibility as Larg learns to assess his capabilities realistically.

What Ride the Wave lacks in aesthetic heft compared with original Irish surfing doc Powers of Three, it compensates for with a satisfying acolyte’s journey: breath-hold and jetski training sequences; a meeting with a safety expert who tells Larg to relax and “enjoy” wipeouts in order to survive them, then shows him pictures of horrific injuries; a loopy Irish shaman who gives Larg pep talks about his two great challenges – the Atlantic Ocean and girls. It’s a testament to how the film believes in its own relaxed credo of running with your personal tides that, when Larg’s moment finally comes, it’s water off a duck’s back.

• Ride the Wave is released in cinemas on 9 September.