If you can't beat 'em, spoof 'em.

On Friday at 8 p.m., NBC's "Riptide" will have a good laugh at itself in an episode spoofing "Moonlighting," the hit ABC show that booted "Riptide" out of its longtime Tuesday 9 p.m. slot.

In "If You Can't Beat 'Em, Join 'Em," "Riptide's" three marina-based detectives will become technical advisers for a TV detective series whose two bickering stars look and act suspiciously like "Moonlighting's" Maddie Hayes (Cybill Shepherd) and David Addison (Bruce Willis).

"We're sort of saluting the show that threw us off the air," said "Riptide" executive producer Babs Greyhosky, who also co-wrote the episode with writer-producer Tom Blomquist. "All of us here are fans of `Moonlighting.' "

Because of "Moonlighting's" ratings success, "Riptide," once a solid hit, is now "in the gray area" in terms of its chances for renewal, according to Dan Filie, NBC director of current drama.

Though a good portion of Friday's episode uses clips from "Riptide's" three seasons to poke fun at itself, some of the more subtle humor is aimed specifically at "Moonlighting" devotees.

The Maddie character, played by Annette McCarthy, is often seen in close-ups through a high filter, "way way over-exaggerated" from the soft lens often used on Shepherd, Greyhosky said. The character also wears Reebok tennis shoes, lampooning Shepherd's own real-life penchant. (She wore orange Reeboks at the last Emmy Awards ceremony.)

The Addison character, played by Richard Greene, is "a dead ringer for Bruce Willis," Greyhosky said, and will sing, as well as speak, accordingly.

"Moonlighting's" rapid-fire dialogue was also attempted. "We gave it our best shot," Greyhosky said. "We don't have Bruce Willis and Cybill Shepherd. We're stuck with what the actors we have can do."

Right before filming began, Stephen J. Cannell Productions, producer of "Riptide," found itself stuck with a few guidelines from ABC. Chief among them, Greyhosky said, was that the Maddie character could not be blond. McCarthy is a blond, so her hair was tinted for the role.

That was the major resolution to a brief squabble between ABC and Cannell Productions over the spoof.

"It came down to a battle of the business affairs divisions," Greyhosky said. "Our lawyers called their lawyers and they all legalesed each other to death."

Greyhosky said she had not spoken to nor heard from Glenn Caron, creator and executive producer of "Moonlighting," but she figures "he might call after the show." NBC, she said, "had very little reaction."

Filie, the liaison between the network and "Riptide," said that he saw Friday's episode less as a takeoff on "Moonlighting" and more as a "wraparound show" that intersperses some original material with flashback clips. "It's an interesting way of doing a clip show as opposed to sitting around a campfire," he said.

A clip show typically is used as a cost-saving measure, Filie said. "Riptide" has been "spending a lot of money this year," he said.

NBC did promote the episode as a send-up of "Moonlighting" in its press materials, but Filie said there "was not a grand design to lure `Moonlighting' viewers. It's nothing that carefully constructed."

"In 22 different stories a year, producers certainly look for any refreshing ideas they can come upon."

But there's a certain irony to this particular spoof. Until "Moonlighting," Cannell was the king of detective "dramedy" (rhymes with comedy), networkese for a one-hour mix of drama and comedy. "The Rockford Files," which he co-created, broke many of the detective genre's rules in a humorous fashion: Rockford often got beat up or thrown in jail, his pockets were usually bare and he lived with a father who couldn't understand why he didn't get a respectable job, like truck-driving.

Cannell shows, such as "The Greatest American Hero," "The A-Team" and "Riptide" similarly leavened action with humor.

Then along came "Moonlighting," and with it another leap through the dramedy barrier.

"You churn these things out week after week and year after year, and everyone gets set in their ways," Greyhosky said. "It takes a person with a lot of conviction to say, `Why?' and try something else. That's what Glenn (Caron) did with `Moonlighting.'"