Guys vs. gals on high seas

Nasty, brutish and short, “Donkey Punch” -- part of Magnet Releasing’s “Six Shooter” series of genre workouts from different countries -- turns a sun-kissed sex-and-drugs bender on a borrowed boat into a gruesome hostage thriller. It’s got enough formulaic flair to make it a guilty-pleasure cousin of seaborne nailbiters “Knife in the Water” and “Dead Calm.”

Director Oliver Blackburn’s background in music videos helps him whip up a tone of carefree flirtatiousness as three English gals on a party-hearty holiday in Spain agree to join a quartet of roguish young men on the luxury yacht they’re crewing on for the summer.

Between the Champagne, Ecstasy and giggly sex talk, below-deck hookups seem a foregone conclusion, as does the emergence of a video camera for porn-tape posterity. But when one bloke opts for a titular sexual practice, things turn disastrously fatal.

What follows in Blackburn’s and co-writer David Bloom’s scenario is a closing of the ranks along gender lines, the dudes determining how to avoid legal liability and keep their visitors in line -- “Why don’t you fix us a meal?” one of the sneering louts ungentlemanly barks -- while the wigged-out girls (among them Ray Winstone’s sweet-faced daughter Jaime) detect an increasingly hostile captivity, one in which a flare and an outboard motor come in handy as weapons.

The gore is thick, but the accents might be thicker: You’ll spend plenty of time straining your ears deciphering the workmanlike British cast’s dialogue. But as a cautionary B-movie for the “Girls Gone Wild” generation, “Donkey Punch” isn’t without a certain power as it gleefully turns its careless hedonists into caged, paranoid rats.

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“Donkey Punch.” MPAA rating: Unrated. Running time: 1 hour, 39 minutes. At the Nuart, 11272 Santa Monica Blvd., West Los Angeles, (310) 281-8223.