The first thing to remember when christening a ship is to take a good swing. If the bottle doesn't break, it's truly an ill omen - for the ship, not the wielder of the champagne, though she may come in for some whispered criticisms for being a weakling. So, you see, christening a ship can be a pressure situation.

But what a glorious time it can be, too, even when it rains, which it did last October when Maryon Allen, wife of Alabama Sen. James Allen, christened the Birmingham at Newport News.

"I wound up from the floor," she related yesterday before 135 members of the 662-member Society of Sponsors of the U.S. Navy - the champagne wielders - sat down for lunch at the Mayflower. "My son said I was the greatest thing since Reggie Jackson."

So a tap of the bow won't do, and there were stories circulating yesterday about stubborn bottles and bungled assignments though, of course, nobody was mentioning names. Harriotte ("Spell it right") Smith, author of two volumes on Navy ships, said she took an especially hefty whack at the Tarawa in 1945 because she had fair warning.

"Adm. Jones was in command of the Navy yard in Portsmouth, Va., and had been in command of the Maryland, the flagship of the battle of Tarawa, in the Pacific in 1943, and Gen. Shoup, later the commandant of the Marine Corps, was there," she recalled.

"Gen. Smith, my husband said, 'Happy, if you don't break the bottle we'll put a lifesaver on you and put you out until you do it." And Adm. Jones said, 'Forget about the lifesaver, we'll just throw her overboard.'

"Well, when I finished, Adm. Jones said, 'You know, Happy, you're supposed to break the bottle, not the ship.'"

Christening a ship, one sponsor said, "is like having a baby or getting married, one of the few great events of your life."

It qualifies one for membership in the 70-year-old society, which includes the wives of five (and daughters of two) presidents, relatives of government officials, and descendants of naval and other heroes. Its principal project is offering financial support to worthy prep schoolers bound for the Naval Academy, and it's obviously a very efficient organization. Adm. Stansfield Turner, CIA director, said he received his invitation to address yesterday's luncheon eight months ago.

Wilma Miles, tall, white-haired, and good-natured, mentioned that most members follow closely the developments associated with their ships.

This is a practice, she said, that was firmly established by the founder, Keith Frazier Somerville, 93, of Cleveland, Miss. Miles said Somerville christened the Tennessee in 1904 (she was a Tennessee senator's daughter), which went aground and sank off Haiti. After that, Somerville met with the survivors at their annual gathering for 50 years, the best example of someone keeping in touch Miles said she could recall.

Though Somerville couldn't make it yesterday, another 93-year-old did, Mrs. Royal Eason Ingersoll. Her daughter-in-law, Helen Davies, had christened a ship, too, the Ingersoll, named for her husband and his grandfather. She had help from her sister, Davies said yesterday. "I hit it backhand low and she hit it forehand high."

Roberta Burke, Adm. Arleigh Burke's wife, also came, though he didn't. She explained: "He is a fighting man and this is not a fighting occasion." She said he was gardening and that no doubt the rain would soften the dirt for him. A humble woman, it soon became apparent, she passed a note on the back of her name card to a reporter, saying, "If you are short of space, please delete Mrs. Burke, the least of all Sponsors." (Another woman tried to give the reporter a quarter to send her a copy of the story.)

Mrs. Miles spotted a familiar face at another table. "He was lighter than air," she said, meaning naturally, that he was skipper of a dirigible.

Another gentleman Adm. Lloyd Mustin, helped his wife Emily recall the fate of the ship she christened in 1938, the Mustin, named for her father-in-law. "It was used as a target ship in the Bikini bomb test," he said. "It survived that, but it was finally sunk as a target by other ships, of which may destroyer was one."

Margaret Murdock of Seattle said her ship, sent on her way at the unusual christening hour of midnight, was given to the Italian navy, and now patrole the coast of Italy. Mrs. John Perry said her ship is now the flagship of the Indonesian navy.

The society's president, Mrs. M. Russell Kelley, who was wearing a purple orchid, said she gets to see a number of christenings and recently attended one, the Duncan, performed by the society's newest member, Mrs. Donald B. Duncan of Pensacola, Fla. When Mrs. Duncan poured coffee for others seated at her table, another remarked, "That's a good intiation for her."

Mrs. Andrew McB. Jackson ("When you're named Andrew Jackson, you like to get the big 'm', little 'c', and big 'b' into it") said she wasn't as worried as she might have been when she christened the Shreveport in 1955. She had gone out and practiced the day before.

She allowed that it was well worth it and not at all wasteful. "It was very cheap champagne," she said.