For decades, there’s been a clear delineation of roles in the Affleck clan: Ben’s the leading man, Casey’s the character actor. Ben has the perfect chin and lustrous hair, not to mention the major height advantage. (He’s almost six inches taller than Casey, according to IMDb.) In the rare cases when Casey Affleck takes a central role in a film, it’s almost always in material that explores the unlikelihood of a guy like him becoming a hero (think The Assassination of Jesse James By the Coward Robert Ford or Gone Baby Gone). That’s not the case in the new historical adventure The Finest HoursThere’s nothing quirky or unconventional about Affleck’s charisma here. Even with a more traditional leading man co-anchoring the story and serving as its de facto protagonist, Affleck commands the screen with steely resolve and smoldering eyes. At 40 years old, he’s blossomed into a full-fledged movie star.

He plays Ray Sybert, the assistant engineer on the oil tanker SS Pendleton, which is trudging towards Boston through a brutal nor’easter in the winter of 1952. Ray begs the ship’s captain to slow down; the bad weather and rolling seas threaten to burst a weld in the tanker’s hull. The captain ignores Ray’s advice, and the engineer’s worst fears come true; the Pendleton splits right down the middle. In the chaos, Ray and several dozen other sailors find themselves trapped aboard the ship’s stern. With no radio, no captain, failing engines, and dissension in the ranks, it falls to Ray to rally the survivors and keep the Pendleton above water long enough for the Coast Guard to mount a rescue mission.

That rescue comes in the form of Bernie Webber (Chris Pine), a soft-spoken, rule-following Coast Guardsman stationed in Chatham, Massachusetts, just a few miles from the Pendleton’s remains. With most of the region’s resources devoted to rescuing the crew of another oil tanker that split in half in the same punishing storm, Bernie, a four-man crew, and a 36-foot lifeboat are all that’s available to save the Pendleton survivors. Bernie accepts the orders given to him by an inexperienced commanding officer (Eric Bana) even though they’re tantamount to a suicide mission; the Pendleton lies beyond a sandbar (or “Thuh BAHHH,” as everyone onscreen calls it in their thick, frequently unconvincing Bahston accents) that is impossible to navigate in churning seas, with massive waves that could flip their tiny vessel and kill them all.

All of The Finest Hours’ emotional stakes lie with Bernie; the early scenes show him meeting lovely Miriam (Holliday Grainger) on their first date, and chart their tentative courtship. She proposes marriage just before the storm hits and Bernie risks his life to save the Pendleton crew. As the situation grows desperate in the Atlantic, director Craig Gillespie frequently cuts back to Miriam on shore, as she confronts Bana’s character and stares soulfully out at the ocean. But even with all the emphasis on Bernie and Miriam, it’s Affleck who makes the biggest impression, despite the fact that he spends most of his screen time hunched over instrument panels, glowering at his skeptical crew from behind perfectly tousled bangs (seriously; his bangs-wrangler deserves a raise). The scene where he pitches the crew on his last-ditch plan while meticulously peeling the shell off a hard-boiled egg is more captivating than a hundred special-effects shots of oil tankers cracking down the middle.

That’s not to say The Finest Hours’ effects aren’t impressive; they often are, and Gillespie does a fine job of incorporating them into three different strains of action on land and sea. The drama — Bernie and his team (which also includes John Magaro and an underutilized Ben Foster) racing against time (without a compass!) to find the Pendleton while Ray and the rest of the crew hold out as long as they can — is predictable and, at times, very familiar; it’s basically The Perfect Storm with the possibility of a happy ending. (Those concerned about spoilers, are advised not to read the real-life incident’s Wikipedia page, or the book based on these events, or the movie’s title.) But if The Finest Hours is light on surprises it’s still heavy on suspense, as the script by Scott Silver, Paul Tamasy, and Eric Johnson treats each new obstacle in Bernie and Ray’s paths as a new brainteasing puzzle with an impossible solution. How will they figure their way out of this one?

Movies based on true stories always come with questions about the degree to which the filmmakers enhanced their true story with dramatic license. There are a couple of moments (and a subplot involving Miriam in jeopardy on land) in The Finest Hours that feel invented for narrative convenience. But the moments that feel inaccurate still hit powerful emotional notes, and the movie delivers the warm-and-fuzzies expected from this sort of inspirational melodrama. Even better, the movie doesn’t spell everything out. It doesn’t explain nautical terms or the intricacies of the rescue mission unless there’s a character onscreen (like Miriam or Magano’s inexperienced sailor) who’s unfamiliar enough with what’s going on to believably ask a question on the audience’s behalf. A lot of stuff is left unsaid, most of all by Affleck, who gives a magnetic performance worthy comparison to great Hollywood brooders like Montgomery Clift. These are certainly some of his finest hours as an actor.