This isn’t a sequel to “Up the Creek,” the puerile 1984 “Animal House” descendant about a crew of college doofuses who compete in a river raft race against one crew of overprivileged preppies and another from a military academy, but it might as well be. In “Without a Paddle” three twenty-something childhood chums (Seth Green, Matthew Lillard and Dax Shepard) decide, after the funeral of the pal who’d been the fourth member of their quartet (a blink-and-you’ll miss him turn by Anthony Starr, who gets only a bit more screen time than Kevin Costner did as the corpse in “The Big Chill”–which was none), to take a canoe trip down an Oregon river that their dead friend had planned not only as a reunion journey but as an expedition to search for the loot stolen by D.B. Cooper (one of their childhood obsessions, along with “Star Wars” paraphernalia). The bumbling trio run quickly into trouble, of course, not only from the rapids and an intrusive bear, but from a couple of burly pot-growers (Ethan Suplee and Abraham Benrubi) whose operation they stumble onto and accidentally set ablaze (cue the expected dazed-by-drugs sequence). The movie then turns into a cartoonish chase in which the boys are pursued by the “Deliverance”-like duo, bumping occasionally into comic supporting characters like two buxom beauties who call themselves Flower and Butterfly (Rachel Blanchard and Christina Moore) and live atop a redwood to save the tree from lumbermen, and a shaggy hermit (Burt Reynolds) who has a predictable link with Cooper. Of course, our heroes mature as their adventure goes on–though, truth be told, that is the story’s most improbable element.

The combination of “Three Stooges” slapstick, “Road Runner” frenzy and sentimental male bonding in “Without a Paddle” doesn’t descend to the gross-out levels of most pictures of this type, which is a blessing, but it never achieves the sort of lunacy and sweetness it’s aiming for, either. Much of your reaction to it will probably depend on your attitude toward the leads. From this perspective, Green certainly comes off best. He’s adept at nerdy types, and Dan Mott–the uptight doctor he plays here–is right up his alley; but Green is also able to give the oversensitive physician a touch of dweeby charm that’s very welcome in this context. Unfortunately, he’s partnered by two fellows who are entirely too successful in making their characters’ obnoxiousness credible. Lillard, whose fingernails-on-the-blackboard shtick is well known, represses none of his smarmier instincts as Jerry Conclaine, the yuppie type who “can’t commit” to his girlfriend because he’s just a big kid at heart, while Shepard, best known for his work on Ashton Kutcher’s MTV series “Punk’d,” is thoroughly convincing as Tom Marshall, a self-absorbed slacker lout prone to exaggeration. Neither of them, unhappily, is particularly adept in presenting the lovable side both figures are also supposed to possess. Better are Suplee and Benrubi, even if Elwood and Dennis, the drug-growers they play, are one-note characters who become increasingly tiresome as the chase drags on. As for Reynolds, about the best one can say is that he’s barely recognizable beneath an ample grey wig and beard that may be a terrible makeup job but is still a good deal more becoming than the awful toupees he usually sports; Blanchard and Moore do their time-warp blissfully dumb hippie number well enough.

For a picture of its type, “Without a Paddle” has been pretty nicely packaged. The locations (in New Zealand, not the American Northwest) are attractive, and Perry Andelin Blake’s production design and Jonathan Brown’s cinematography make good use of them. Director Steven Brill, as his previous movies (“Heavyweights,” “Ready to Rumble,” “Little Nicky,” “Mr. Deeds”) have demonstrated, is pretty much a stranger to subtlety, but at least he nudges things along without wasting too much time and doesn’t linger too shamelessly over the “insightful” moments.

One could discourse learnedly on the homoerotic undertones of “Paddle,” especially in scenes like the one where Dan, Jerry and Tom, stripped down their undies, huddle together for warmth in the chilly rain. But one should probably dwell on that no more than one does on the nocturnal habits of Moe, Larry and Curly. Just be content instead with plays on the title: without a brain, without a hope, without a laugh…. The last, though, is actually unfair: there’s one fairly clever moment in the picture, when Elwood and Dennis are arming themselves, Rambo-style, to go after the boys and the former advises his dumber comrade to leave behind his beloved cleaver on grounds that it’s scary, but ineffective. For a moment you brighten up, hoping for more of that to come. Unfortunately, the rest of “Without a Paddle” leaves viewers almost as stranded as its klutzy threesome; it may not sink as far into the muck as most movies of its type, but despite its treasure-hunting theme it unearths no comic riches.