Movie audiences, safely sucking on a soda straw and sitting in comfortably plush theater seats, love to watch desperate characters struggle against the elements. The survival movie crosses many genres—this year alone included Matt Damon’s sci-fi quest to stay alive in The Martian and the nature-thriller Everest—but nothing inspires the survival epic more than the sea. From All is Lost to Unbroken, the remoteness of the ocean tests the breaking point of the minds and bodies of men, which is why Nathaniel Philbrick’s 2000 book In the Heart of the Sea: The Tragedy of the Whaleship Essex, about a ship felled by a whale in 1820, was a natural Hollywood choice. Even more alluring is the fact that the whale that caused the shipwreck of the Essex was Herman Melville’s inspiration for Moby-Dick. (First mate Owen Chase published an account the ordeal in 1821 titled Narrative of the Most Extraordinary and Distressing Shipwreck of the Whale-Ship Essex.) Unfortunately, the temptation to focus on the Moby-Dick connection rather than true story of the Essex is the film’s undoing. Caught waffling in the doldrums between the fictive genius of Moby-Dick and the real-life drama of Philbrick’s book, In the Heart of the Sea is crippled by the narrative choices of the screenwriters.

Ron Howard knows the power of a true story told well—Apollo 13 is one of the greatest survival stories of all time—so the extent to which In the Heart of the Sea is derailed by its divergence from the original is alarming. Especially because, unlike other “based on a true story” films, the true story of the Essex is far more dramatic than Howard’s film: After the ship is rammed and sunk by a whale, the twenty survivors spent 96 days at sea; only eight survived—some resorting to cannibalism.

In the Heart of the Sea is structured as a frame narrative: young Herman Melville, played by Ben Wishaw, is hoping to write a book about whaling. He visits Thomas Nickerson, an aging sailor who was the fourteen-year-old cabin boy on the Essex, to draw out the story of the whaleship. (This meeting is a historical mash-up: Melville did travel to Nantucket to meet with the whaleship’s captain, George Pollard; decades later a different writer met with Nickerson and collaborated with him on a book about the Essex.) Nickerson is a man tortured by his past, unable to tell even his wife the true story of what happened. These scenes feel like treading water: Nickerson is little more than an old drunk with regrets, and Melville, despite Whishaw’s genuine skill at expressing inner depths using only his eyeballs, just an anxious writer. (The scenes with Nickerson and Melville are also the beginning of the confusing accents that plague almost the entire cast, who veer away from New England towards something that lands between a Southern drawl and Scottish brogue.)

As the story moves back in time the focus shifts from Nickerson to Captain George Pollard (Benjamin Walker) and First Mate Owen Chase (Chris Hemsworth), who are cast in yet more archetypical roles with Pollard as the privileged but under-experienced leader and Chase as the deserving but unfairly ignored working-class man of the people (Too often, Hemsworth comes across as Thor with a harpoon). Unlike Ahab and his crew, the Pollard vs. Chase narrative lingers without making an impact—a conflict which, in a very un-Melville manner, fails to link up with any greater themes.

Screen time could have been better-used to make the sailors on the Essex distinguishable from one another—even before the cast grows shipwreck beards and become similarly sunburned and emaciated, they are difficult to tell apart. Various crewmembers scramble up creaking masts and let down whipping sails, and in one notable scene crawl into the body of a whale to remove some spermaceti, but the eventual tragedy of their deaths is undermined by confusion over who, exactly has died.

These narrative failings are all the more perplexing because they come at the expense of compelling real events of the 1820 sinking and survival. Readers of Philbrick’s book will be confused by Howard’s choices about what to cut and change; most of the central tensions that animated the book have been excised. The crew’s decision, motivated by a fear of cannibals, to not sail their lifeboats to Polynesia—which sent them on a longer journey to South America that turned them, ironically, into cannibals—is never mentioned. The cannibalism itself, which is supposedly what so haunts the old Nickerson, is downplayed; the movie implies that only a few men were eaten when Philbrick makes clear that the real total was somewhere around seven. The fact that all the black crewmembers on the Essex died first, likely because their pre-wreck rations were worse than their white counterparts, is also not mentioned; in the film, one black crewmember survives, allowing the filmmakers to erase a horrifying history that could have helped the film stake a claim to contemporary relevance.

A few scenes in In the Heart of the Sea hint at how effective the film might have been if told purely as a gripping story of man versus nature. When a storm overpowers the ship, the water blots out the sun, reducing the scene to shades of black and white. Later, rendering the whale oil, the ship becomes a vision of hell lit by orange smoke, accented by white cubes of chopped blubber. The best shots are consistently underwater: ink running off a submerged log book, whale pods moving gracefully through the gloomy depths. The elements in In the Heart of the Sea are beautiful and dangerous; water, sun, sand and flesh simultaneously torment and offer salvation. The meditation on human frailty is disrupted by Chase’s half-hearted obsession with the white whale—another narrative garnish imported from Moby-Dick to fill in a perceived gap in Philbrick’s book. But while the white whale and Ahab’s obsession with it drive Moby-Dick, they do so as powerful symbols. Turning Chase and Pollard into mini-Ahabs for the sake of a single scene of a limp psychological breakdown distracts from the story of survival that should have remained central to the film.

Philbrick and Melville’s books are both masterpieces, and each draws their power from different sources. Philbrick delivered powerful facts unadorned by false melodrama, and Melville used forceful imagery to examine questions of good and evil. In the Heart of the Sea kills the power of Melville’s masterpiece by reducing his metaphors into reality, and kills Philbrick’s sea yarn by both importing stock drama and as well as flinching away from the most horrible parts of the true story. In the middle of the film, Melville confesses his anxieties about writing his whale novel to Nickerson. “I fear if I do write it, that it will not be as good as it should be,” he says. Melville’s novel was as good as it should have been; this film is not.