BY ROGER MOORE

McCLATCHY-TRIBUNE NEWS SERVICE

Watch any surfing documentary, from "Whipped!" to "Riding Giants," and you'll hear the dudes speak--in hushed tones--about the treacherous and epic waves that show up off the coast of Northern California when the conditions are just right.

The Mavericks break is legendary, and for years, was considered some sort of myth by those who surfed and had never seen it.

"Chasing Mavericks" is about the days when that break was acknowledged as real, and the teenager--Jay Moriarity--who became famous there.

Jonny Weston is Jay, a curly-headed blond who has gotten the surfing bug from his somewhat standoffish neighbor, Frosty.

The older surfer, played by Gerard Butler at his most gruffly charming, has a job-- roofing--a gorgeous wife (Abigail Spencer) and a growing family. But his passion is surfing.

All flowing locks, a regular Adonis-on-a-long-board, Frosty is one of the "children of the tides," he poetically narrates. And his secret is Mavericks.

In a brief prologue, we learn of Jay's working-poor background--his alcoholic, semi-employed divorced mom (Elisabeth Shue) and his absent father.

Cooper Timberline plays the 8-year-old Jay, who tapes together a busted board, braves bullies, gets his nose bloodied by the surf, but who sticks with it to become the best surfer kid on the block by the time he's 15.

He lionizes Frosty, and stows away on the guy's ancient Ford Econoline van when Frosty sneaks off to Mavericks, of which only a quartet of veteran surfers are aware. They know what the conditions are and are skilled enough to handle waves as high "as five-story buildings, a thousand tons of water pounding you, holding you down."

Those are Frosty's warnings to the boy. But when his wife points out that "there are all kinds of sons," Frosty mentors the kid--trains him for that magical three-month window when conditions make Mavericks an epic ride.

The dynamic here is that Jay is the more grown-up of the two. He's keeping his lonely, depressed mother afloat and employed. Frosty is missing his daughter's childhood, ditching work, lying to the wife to surf.