Hours: Luncheon on Fridays only, from 11:30 a.m. to 2:30 p.m. Dinner on Mondays through Saturdays from 5 to 10:30 p.m. Closed Sundays.

Atmosphere: A touch of French, a touch of Vietnamese and a touch of class, but nary a heavy hand. Not really for tots, but kids who are at least table-top tall will find friendly foods.

Price Range: From marvelous meat balls or chicken at $4.95; to lobster thermidor, at $9.50.

Credit Cards: American Express, Carte Blanche, Diners Club, Visa.

Reservations: Not necessary.

Special Facilities: Not easily accessible by wheelchair, since front entrance involves a few steps. Street parking if you allow time for a tour.

On this night our magical spin of the culinary globe takes us to a nautical port of call where the galley fare is - now hear this - French and Veitnamese. You just know that's got to be one big mix-or-match game for butter buffs and lemon leaf lovers.

Our two children, when apprised of the evening's premise, weren't sure what to expect but were game, nonethless. And what the heck, there's always a chicken in every spot.

To get your bearings, La Fregate is moored on Florida Avenue, a block down Connecticut from the Washington Hilton.

The first good taste here was that which the decor was in. The lighting was soft enough to make you drop your voice but bright enough to let you see where you are and who else is around.

Beams of rich, weathered dark wood - we like to think from some grand old vessel - gave one large wall great class. On another wall, there's a fairly elegant and sizable mural that looks like a jigsaw-puzzle, ocean-and-seagulls scene. To uphold the good name of the place, there's also a model of a frigate on the wall.

Our host wore a snappy borwn leather jacket, topped by a wide grin. He lit up the large hurricane lamp in the center of the table and we promptly showed our Vietnamese savoir-faire by suavely ordering two margaritas and two Cokes.

The menu is not one of those by-the-numbers, 60-choices-from-two-columns directories. It's a compact list of intriguing options with a little something that should satisfy any taste.

Our 11-year-old son is into soups, as they put it nowdays, and the soup that would be into him this time was French onion, at $1.95. However, the soup-son wasn't bowled over, as it were; he reported that things were slightly different - not really very oniony and, if you must know, only marginally interesting. I did much better in this department just by winging it. At first I was torn between Pho and Hu Tieu, not because I had the slightest idea what either might be, but because Pho was parenthetically described as "Hanoi soup" and Hu Tieu as "Saigon soupe."

It's a little late to take political sides on this question, I thought, but the man in the leather jacket didn't help me out much when I asked the difference. He just shrugged.

Then I did, too, and went for the Saigon with the extra "e" in the soupe. Ask me what was in it, and I'll shrug again - but I liked it. Our panel of partial experts did identify noodles and pork as ingredients. In any event, either Hanoi or Saigon is $1.95.

From the hors d'oeuvres, my wife and our 9-year-old daughter chose to split an order of spring rolls, at $2, a plate of six pleasingly light, finger-like crispies thay you can dip into a sauce.

The entrees are listed in two columns, with the left one featuring Vietnamese specialties and the right your French delights.

Our daughter spotted a favorite in the left column: fired shripm, at $5.50. They were stemless little fellows, crisp-on the outside but sort of soggy on the inside. They came with fried rice.

In the right-hand column our son found veal, or specifically, Escalope de Veau a la Milanaise, at $6.50. If someone who likes to eat these French veal dishes can be called veau -ciferous, he is - and so demonstrated by packing away a handsome slice that was heavily cheesed but snappy, along with spaghetti and a salad.

If you lke meat balls, the secret words here are Nem Nuong, which my wife had the good fortune to select. There were 10 of them, charcoaled on a plate with some wrappers made out of edible rice paper. With a short dunk in the sauce that came with them, these were popular tablewide.

I can't say Ga Uop Ngu-Vi-Huong without looking down at the menu, but if asked again, I'd surely try - for it's chicken with five spices, for $4.95, three tender pieces in rice and gently zingy sauce. Another four-vote favorite.

The service was pleasant but a little erratic on this uncrowded evening.

That didn't stop the kids from adding on a round of two chocolate mousses, while their parents tried to concentrate on their coffee.

All of this binational gluttony - the appetizers, entrees, desserts and beverages - eased our bill to $36 plus tip, which a family with less abandon could underbid and still come out happily fed. When ours came out, we came upon an after-dinner treat - a first-hand look at President Carter leaving a big dinner at the Hilton. The bill for that party of several thousand was not disclosed.