Under The Whaleback, Royal Court Upstairs, London, ***

A sailor legendary for his exploits long before his spectacular death, Cassidy amuses his mates by sticking a firework up his bottom. "At sea," he explains, "you've got to make your own entertainment." As Richard Bean's play shows, life on a fishing trawler out of Hull is such that this diversion would indeed be welcome.

On one such voyage (the play is set on three ships over a period of more than 30 years), foul weather restricts four seamen to their tiny living quarters beneath the forward deck (the location of the title). The ancient Bill, who has frolicked with Inuit girls in his time, carves ornaments out of cods' jawbones. Young Darrel reads A Portrait of the Artist as a Young Man. (In a later speech that exhibits the author's self-indulgence better than his wit, Darrel says that the company's ships "was all named after writers. The Jane Austen, the George Eliot, the Charles Dickens. I always made a point of reading whoever I was sailing in. I enjoyed them all, except for one bad winter in the Virginia Woolf.")

Roc lies in his bunk, trying for obliviousness, which is a wise move considering that the fourth occupant is Norman. Rampaging around in a pink shirt and women's tights, Norman impugns Darrel's manhood, smashes his fist against the woodwork, and whines for someone to get him a cup of cocoa. Norman, you feel, could induce cabin fever in the Royal Albert Hall. When Norman calls Roc's girlfriend a slut, the stage seems set for a brawl – but the sea has other plans.

While it sticks to the rough, bitter dialogue and actions of the sailors, Under the Whaleback is both touching and amusing, but it doesn't go very far – a defect that's especially noticeable in a play set on a form of transportation. Instead of psychology or poetry, Bean gives us social comment, its tone often as pinched as Norman's cry for cocoa. The third ship, on which Darrel made his last voyage, is now a museum, and he is its curator, having checked in at "the joke shop" in vain for over 20 years.

It is symptomatic of the narrow reach of the play that its criticisms are made in the form of such a stale metaphor – and stale, also, is the invasion of this monument to England's despair by a representative of English deracination and violence. The young thug seeks to implicate Darrel in his troubles, but the evil done by men who casually beget children, and then treat their offspring's lives as casually as they do their own, is a subject that should have been explored earlier and more forcefully.

Still, Richard Wilson's production offers much to enjoy, with its uniformly excellent acting, particularly that of Alan Williams as Cassidy, laughing his head off in a shirt splashed with blood, and Iain McKee as the hollow, dead-on-his-feet Darrel of the last act. And Bean is good at puncturing social pretence with a swift thrust. "I respect women," says one of the lads. "You got to nowadays, ain't yer, or you'd never get your leg over."

To 3 May (020-7565 5000)