The opening line of Herman Melville’s “Moby-Dick” is one of the most famous in literature. But Jake Heggie and Gene Scheer, whose moody, monochromatic 2010 adaptation arrived at the Metropolitan Opera on Monday, conspicuously avoid placing those classic three words at the start.

It’s an early declaration of independence, the kind that artists have always had to make when turning a well-known novel — especially one as sprawling and shaggy as Melville’s — into singing. Heggie, who also composed the well-traveled opera “Dead Man Walking” (2000), and Scheer, an experienced librettist, have narrowed one of the canon’s most overflowing works to its core plot.

For readers who enjoyed “Moby-Dick” but yawned through the rambling digressions about whaling, do I have an opera for you.

The compressed adaptation is direct and clear, at least. Some contemporary operas, of which the Met has offered a burst over the last few seasons, lean heavily on confusing devices: complicated flashbacks; characters shadowed by doubles; singers playing metaphorical qualities like Destiny and Loneliness; split-screen-style scenes crossing place and time.

“Moby-Dick” wants none of that. It stretches across a year or so, but in a linear way. It never leaves the ship Pequod and its salty surroundings. Its characters are flesh-and-blood people.

Yet the opera only rarely takes on flesh-and-blood urgency. While the story is streamlined and straightforward — a ship’s crew struggles with the demanding whims of a vindictive captain — Heggie and Scheer also want to capture Melville’s brooding grandeur, philosophical profundity and portentous language.

So the prevailing mood is a dark, ponderous blue — a lot of stern, turgidly paced musings directed straight at the audience. The goal seems to have been to create a piece that’s lucid and vibrant, but also dreamlike and meditative. A piece, in other words, much along the lines of “Billy Budd,” Benjamin Britten’s opera based on another seafaring Melville tragedy in which a ship becomes a petri dish for archetypal struggles.

This is where the ambitions of Heggie’s “Moby-Dick” adaptation run up against his limitations as a composer. “Billy Budd” fascinates because of the haunting complexities of Britten’s music, but the meditations in this “Moby-Dick” end up feeling dully one-note, as shallow as a tide pool.

Even the circumscribed world of the opera includes a storm, a mast lit up by St. Elmo’s fire, intimations of the South Seas, night and day, stillness and dance, vast expanses of sky — yet the music fails to meet the demand for these textures and colors. Heggie doesn’t have many ideas beyond squarely undulating minor-key references to Philip Glass, John Adams and Britten himself. Every composer’s work has influences, but these quotations are startlingly unadorned, even if played with spirit by the Met’s orchestra under the conductor Karen Kamensek.

Lovers of traditional operatic forms will find much to admire here, as Heggie and Scheer have embraced the kind of ensembles — duets, trios, quartets — that allow this art form to present multiple perspectives at once. But the variety in the text is not matched by variety in the score, and the conflicts that should energize the story don’t always feel vital.

The real tension is — or should be — between Captain Ahab, whose obsessive pursuit of the whale Moby Dick has drowned his humanity, and Starbuck, the sensible first mate who tries to steer the whole operation clear of disaster.

But the opera gets distracted by a side plot about finding brotherhood amid racial and religious difference: Greenhorn — the name the opera gives the novel’s narrator — first fears and then befriends Queequeg, the Polynesian harpooner.

It’s not until nearly an hour and a half into the three-hour opera that it really holds your attention for the first time. In a ruminative aria, Starbuck mulls whether to murder the sleeping Ahab to save himself and his shipmates. In the end, he can’t bring himself to do it, and he slinks out as Ahab softly moans and the curtain falls.

The sequence is riveting — but we’ve waited until the end of the first act for it. For the other highlight, we have to wait again, until late in the opera, when Ahab finally lets down his guard with Starbuck and confronts the cost of his single-minded mania. It is the calm before the final, doomed hunt, and Heggie endows it with real tenderness.

Ahab, though, primarily expresses himself through drearily similar monologues, grounded in Melvillean diction and given a similarly antiquated musical feel through robustly shaking Handel-style coloratura. The tenor Brandon Jovanovich, stalking the stage with a belted-on peg leg, conveys a sense of Ahab’s weariness more than of his intensity.

The cast is entirely male, with the exception of the soprano who plays the young cabin boy Pip; Janai Brugger captures the boy’s otherworldly purity. The baritone Thomas Glass was a solid Starbuck and acted with remarkable confidence, given that he was announced as a replacement for an ill Peter Mattei just a few hours before the opening on Monday — a performance that began with the orchestra playing the Ukrainian national anthem, the Met’s latest gesture of solidarity with that country.

While the tenor Stephen Costello was a plangent Greenhorn, the bass-baritone Ryan Speedo Green sounded underpowered as Queequeg, with little to do except intone native prayers. The sweet-toned tenor William Burden was piquant among the smaller roles.

Leonard Foglia’s handsome production, with sets by Robert Brill, costumes by Jane Greenwood and lighting by Gavan Swift, is dominated by masts and rigging. The deck cleverly curves up into a backdrop that cast members can climb up and tumble down, seeming — with the help of Elaine J. McCarthy’s projections — to be lost at sea as their boats are broken in the whale hunts.

It is a clear staging of a clear piece. But that piece lacks the ingenuity and depth to hold its own with its source material, let alone break free. And it turns out that Heggie and Scheer’s opening salvo of independence was just a coy deferral until the opera’s closing moment.

As Greenhorn, the Pequod’s only survivor, is rescued by a passing ship, the captain asks his name. Costello answers, singing low and mournful: “Call me Ishmael.”

Moby-Dick

Continues through March 29 at the Metropolitan Opera, Manhattan; metopera.org.