Two tremendous early-19th century sea battles comprise the bookends for director Peter Weir's ambitious "Master and Commander: The Far End of the World," an adaptation from two of Patrick O'Brian's celebrated British epic maritime novels that is accurate down to the bloody palm prints of injured sailors steadying themselves on five-and-a-half-foot ceilings below decks.

The film has no story arc to speak of -- it's just a Napoleonic-War cat-and-mouse game between the handsome 28-gun English frigate HMS Surprise and the Acheron, a faster, heavier, better-armed French privateer that Captain Jack Aubrey (Russell Crowe) has been ordered to "sink, burn or take her as a prize" before it can round Cape Horn and spread the war into the Pacific. But even as a linear tale of battle strategy and personality that lacks a first act, the film is so well acted and well crafted that it engulfs you in its time and place where "the oceans have become the battlefields."

Opening with a formidable cannon-fire showdown in which the Surprise is caught unaware by her enemy emerging from a fog bank, "Master and Commander" jumps fearlessly into the fray as the British sailors fight for their lives and escape a French boarding party only by limping their battered ship with its shot-away rudder into the same fog bank and vanishing in its blanket of hazy billows.

Refusing to return home for repairs out of a sense of duty more than pride -- the Surprise is Britain's only hope of keeping the war contained -- the firm and confident Aubrey orders a refit at sea and a continued pursuit that keeps the film's narrative entirely onboard this one ship except when the crew goes ashore in Brazil to gather lumber for repairs and trade with natives for supplies.

Co-writer and director Weir ("The Truman Show," "Dead Poets Society," "Gallipoli") rises to the challenge of turning the ship's confines into a terrarium of interesting characters and nautical drama, thanks in large part to Crowe as the dauntless, iron-willed Aubrey and Paul Bettany (who co-starred with Crowe in "A Beautiful Mind") as the ship's sea-novice surgeon and the captain's dear friend.

With an erudite but not aristocratic air about him, Crowe provides a powerful, legend-in-the-making presence that permeates the ship, instilling both confidence and fear in his men -- including a brave 13-year-old midshipman (Max Pirkis) taken under the captain's wing after losing an arm in battle. Crowe even manages to look unquestionably virile and valiant in his breeches and billowy shirts while playing the violin in string duets with the doctor in their downtime.

But as a man with the freedom to show fear and (privately) question authority and priorities due to his close friendship with the skipper, Bettany makes an even more memorable impression as a credible, compassionate surgeon and a modest man of passion and conviction -- who would nonetheless rather collect rare animals while anchored at a small atoll than do just about anything else. This fact causes a rather childish spat between the men that is the film's only out-of-character moment, although it does have a payoff that brings the film back to its epic action core.

When the chase resumes, Aubrey's acumen for cunning naval combat tactics builds "Master and Commander" toward a tense and riveting last act as he rouses his men to fight even as he admires his enemy's proficiency. "England is under threat of invasion," Crowe ardently proclaims in a speech that strikes a resounding chord, "and though we be on the far side of the world, this ship is our home. This ship is England!"

The mortar and man-to-man fracas that ensues is sometimes hard to follow, but its chaos feels real, immediate and lethal as Weir strikingly encompasses the astounding might of the ships -- side by side, blasting jagged holes in each others' hulls -- while also capturing the bloody personal toll of confined and imprecise warfare, circa 1805.

The movie's strange structure that begins in the middle of the story, and in the middle of the sea, never seems to find its narrative magnetic North, through storms and drought, personal conflict and camaraderie, battle and respite. But while "Master and Commander" continues to feel in some ways incomplete, even as the credits roll, it's nothing if not completely transporting.