Based on a true story, Adrift is a tale of survival, love and very wet clothes. Shailene Woodley stars as Tami Oldham, an American traveller who pitches up in Tahiti, falls in love with a British sailor (Sam Claflin) and embarks on a yacht journey with him all the way across the treacherous South Pacific to San Diego.

Such long distance voyages undertaken in tiny yachts – and even tinier shorts – seem to me, let’s be frank, asking for it. Especially in a film called Adrift.

Sure enough, not far into their voyage, the couple are hit by a giant wave that sends the boat spinning and breaks a mast. In fact, this is where we open the film, with Shailene (from Big Little Lies and The Fault in our Stars) waking up in a pile of kitchen implements and a puddle of water, wondering what’s just happened.

The film, directed by Iceland’s Balthazar Kormakur, uses a flash-back structure, pinging between Tami on the boat trying to fix the sail and pump out water, and her happier times frolicking in waterfalls with hunky Richard, whom Claflin plays with his characteristic British charm, although there’s something a touch predatory about the way he sets about fancying this younger American girl in her swimsuit and wet T-shirts.

By the time they set sail, we’re supposed to believe that their new-found love is enough to sustain them, whatever the weather and no matter how many cans of beans they have to eat. It doesn’t help that Tami’s a strict vegan and won’t so much as catch a fish, let alone eat it raw like sushi.

What looks like fresh idealism as they set out becomes more serious when the pair find themselves drifting for days in the middle of an unchartered ocean. Richard’s leg and ribs are broken so he’s not much use (Claflin has a habit of getting lumped with this sort of role – he was the quadraplegic lover in Me Before You, the adaptation of JoJo Moyes’ novel) and as they run out of tins, even he can’t persuade Tami to get the harpoon out. That’s the thing with vegans, really – you sort of respect them, but you never want to be stuck with one at meal times. Especially not on a boat.

Eventually the film stops bobbing around and has enough courage to tell its story without flashing back. Shailene’s Tami gets thinner and thinner until she’s just like every other actress in Hollywood; Richard turns a bit green and they’re going nowhere fast. Then Tami has the genius idea of heading for Hawaii instead and using the currents like the ancient sailors did. 

All a bit random really, that this American twenty-four-year-old who’s never sailed before should start  getting a sextant out, navigating by the stars and invoking Pacific folklore. But I suppose having a tantrum and crying about it aren’t going to get you anywhere and this is all about pulling yourself together and setting your mind to survival.

It’s one of those movies where you’re supposed to think – gosh, what would I do in that situation? Of course, I wouldn’t get in the stupid boat in the first place but if I was left alone against the elements, I definitely wouldn’t be able to tie reef knots or fix the mast. I’d be all right with a marlin tartare, though.