“The Finest Hours” is based on one of the Coast Guard’s greatest rescues, a miraculous event where a small boat braved treacherous conditions during a blizzard in 1952 to save sailors on sinking oil tankers.

It’s a powerful story, the kind told with stern, honest men who do their job and keep their feelings inside. Heroes? Sure, but to them they’re just doing their jobs.

It’s February, 1952, in a small coastal Massachusetts town. A massive nor’easter is bringing dangerous winds and weather, and it’s catastrophic for a pair of oil tankers caught in it. Amazingly, both tankers are split in two.

Chris Pine plays Bernie Webber, a young Coast Guard boatswain who is tasked with the mission of saving the men on one of the ships. But it could be a suicide mission. The seas are wild, visibility is awful and then there’s the sandbar, which could keep the rescue ship from even getting out to the open seas.

Meanwhile, aboard the tanker, Casey Affleck’s quiet Ray Sybert has to bring together the survivors — who are divided on the best way to stay safe — to keep the remaining half of the ship afloat long enough for a rescue ship to save them — which isn’t even a sure thing as the radio is kaput and they’re relying on someone hearing their horn.

“The Finest Hours” is an old-fashioned disaster film, with powerful scenes of destruction, steely stares off into space and gruff talk. It’s a film split in three: You have Webber’s trip with his crew, Sybert’s sinking ship and the people back on land, including Webber’s girlfriend, Miriam (Holliday Grainger), who is learning the life as the significant other of a Coast Guarder is never going to be easy.

All together, the film runs long (it clocks in at nearly 2 hours) and can be repetitive — there’s always another big wave, or the water is creeping up ever so rapidly in the tanker. Plus, the jargon can be very confusing for those of us who aren’t familiar with the seafaring world.

But it’s impossible to dismiss the visceral action scenes with each ship. It’s a very stressful experience, which is a real testament to director Craig Gillespie (“Lars and the Real Girl”), who was able to bring true suspense to a real-life story.

Pine does a fine job as Webber, bringing real determination to his role. But it’s Affleck who really steals the show here with a wonderfully acted performance.