Two films on the same subject – the attempted round-the-world voyage by amateur sailor Donald Crowhurst in 1968, for which the term ‘ill-fated’ is a grotesque understatement – but miles apart in their approach. Not to say budgets: with Colin Firth in the lead and Rachel Weisz back at home as Crowhurst’s loyal wife Clare, THE MERCY is similarly well-appointed when it comes to telling the story, luxuriantly recreating the scenes on the Devon coast from where Crowhurst sets sail in his trimaran ‘Teignmouth Electron’ as he bids to win the £5000 prize offered by the Sunday Times in its Golden Globe race.

Operating at about a fortieth of THE MERCY’S cost, CROWHURST the movie seems by contrast as cash-strapped as Crowhurst the thwarted family man was in real life. His career as a travelling salesman in electronics was going nowhere, and there were few takers for his own invention, the ‘Navicator’, a sort of high seas sat-nav, as we see from THE MERCY’s opening scene at the 1968 Boat Show, which as promoted by the Daily Express used almost to be part of the London social season. Here the recently knighted Sir Francis Chichester, fresh from his own successful circumnavigation in the ‘Gipsy Moth’, inspires Crowhurst by describing his own exploits as a refusal ‘to only do what has been done before’.

Fired with optimism, Crowhurst finds a local backer, caravan magnate Stanley Best (Ken Stott) and an ambitious press agent Rodney Hallworth (David Thewlis) who soon recruits a slew of beer and tinned goods manufacturers ready to sponsor Crowhurst in return for their products being wanted on voyage; more ominously – a scene tensely dwelt on in CROWHURST – Stanley Best demands the signing of a draconian contract whereby Crowhurst will be obliged to return Best’s money in the case of failure, by implication forfeiting all his assets which include the home to his wife and four young children.

But failure isn’t on the agenda as Crowhurst leaves Teignmouth on October 31st, the final deadline for departure which means he can wait no longer for a pump and essential seals to make the hatches watertight. Hallworth has assured him that he’s already a national hero, that he represents (quoting Churchill) ‘a part of England that’s been lost’. Besides the tins of corned beef and crates of beer (and the gift of a toaster from his family), the BBC has bought the rights to Crowhurst’s voyage, equipping him with tapes for a step-by-step recording of the adventure.

Which immediately starts to unravel. Sure enough the hatches leak: CROWHURST graphically shows him waking up in the cabin and putting his feet down in inches of sea-water, necessitating bailing it out by hand in the absence of his pump, a process punctuating the many other mishaps from now on. ‘‘Oh good God – not the buoyancy bag” cries Firth in THE MERCY as he sights another disaster at the top of the mast – climbing it perilously to repair the damage recalls James Marsh’s other movie MAN ON WIRE, recreating Philippe Petit’s daredevil tightrope walk between the twin towers of the World Trade Center in 1974.

It is finished – it is The Mercy.

CROWHURST director Simon Rumley’s previous career has included several low-budget horror films, and here he is in his element, documenting the solitary torment and gradual breakdown of Donald Crowhurst (well portrayed by Justin Salinger) as the terrifying truth slowly dawns that in no way is the Teignmouth Electron fit to leave the Atlantic Ocean and confront the Cape of Good Hope and the onward journey; that way lies destruction and certain death. On the other hand, giving up and heading home leads to humiliation and financial ruin. ‘I can’t go on and I can’t go back…what a bloody awful decision’ says Firth’s Crowhurst.

‘No one need ever know’ is Salinger/Crowhurst’s out-loud contribution to what comes next: forging the log-books coupled with the judicious use of radio silence to hide the fact that he need never leave the South Atlantic, then rejoining the race at a tactful distance behind the other competitors after they’ve rounded Cape Horn and started to head for home. The hoax allows Crowhurst to put in on the Argentinian coast to repair a hole in the side of the boat with makeshift pieces of plywood – and in CROWHURST to indulge in a drunken tango in a shore-side bar, as the enormity of his deceit increases his mental disintegration.

This becomes overwhelming with news that one by one his competitors have sunk or otherwise dropped out, leaving Crowhurst to return home the fastest winner, but also to face the inevitable music. Both films take their cue from the last log-books, which include a 25,000-word rambling essay on man’s hapless role in the cosmos (ending with ‘It is finished – it is The Mercy’) but the last section of Rumley’s film addresses full-blown madness with the use of split-screen, hallucinatory colours and nightmare images of dying fish (and a highly effective writhing cable-knit sweater) while THE MERCY shows Crowhurst dropping his chronometer overboard, shortly to be followed we assume by the man himself.

THE MERCY and CROWHURST are both effective in their separate ways, but as a study of abject failure THE MERCY is compromised by its star trappings, a glaring example being Clare/Rachel Weisz’s doorstep diatribe against the press and media gathered outside her house after the circumstances of Crowhurst’s deceit become known (especially as the film has wallowed enjoyably in scenes set at the Sunday Times and with Rodney Hallworth’s enthusiastic publicity wheezes). While constrained by its small budget, CROWHURST makes the most of the contrast between the man alone on the boat, and friends and family singing ‘Jerusalem’ and ‘Silent Night’ as their hero navigates into the heart of darkness.

In a redemptive end caption CROWHURST reports (alongside pictures of the wreckage of the Teignmouth Electron, still beached in the Cayman Islands), that a version of Crowhurst’s invention the ‘Navicator’ is now used by practically every sailor putting out to sea.