For 10 years, Ted Lange played bartender Isaac Washington on 250 episodes of television’s “The Love Boat.” Now the actor, 71, will be pouring drinks as the bartender in TheaterWorks’s holiday perennial, “Christmas on the Rocks,” which plays Dec. 1 to 23.

Q: Have you ever tended bar professionally?

A: No, but “Love Boat” was such a monster hit — both myself and Fred Grandy [who played ship’s purser Gopher] didn’t see it coming at all — that after the first year of the series I went to bartender school so I could learn exactly what a bartender does.

Q: What did you learn?

A: There’s a thing called “the free pour” in which they teach you how to pour a shot right on the dime. And how to cut a lemon a certain way, which is different from how you cut the lime. After I graduated from the school they gave me two diplomas: one for me and one for Isaac Washington and we put that one on the set on the Acapulco Lounge in the show. Hey, you never know when you’re going to need that license when you’re an actor.

Q: What’s the secret of being a good bartender?\

A: Charm. A lady will pull out a cigarette back in the old days and a bartender would have a lighter just like that. But it’s mainly the ability to listen — especially after a few drinks — which is what the “Christmas on the Rocks” character does. It’s like that old Sinatra song with the lyric, “Set them up, Joe, I’ve got a little story I think you should know.”

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