American marine insurers may be tempted to lower hull and cargo premiums in order to compete with Lloyd's syndicates bolstered by new capital after Jan. 1, said David C. Beebe Jr., former chairman of Chubb & Son, Warren, N.J.

But having only recently emerged from an eight-year slump in hull pricing, and facing continued sluggishness in cargo rates, "our business cannot again survive another year without profit any more than man can survive indefinitely without food," he said.Mr. Beebe, outgoing chairman of the American Institute of Marine Underwriters, said U.S. marine insurers have "come through a long profit famine and many of those who remain active are in weakened condition."

American marine insurers' ratio of dollars out to premiums in improved to 103.7 percent last year. In 1991 their combined ratio hit 115.7 percent. That is, for each premium dollar collected, almost $1.16 was spent on losses and expenses.

Mr. Beebe, whose two-year term ended at the AIMU's annual meeting here Wednesday, said U.S. ocean marine insurers can't afford to go back to the old unprofitable days of price undercutting each other, after corporate syndicates at Lloyd's of London are permitted on Jan. 1 to join the society of investors who back Lloyd's commitments with their personal wealth.

"We now have an opportunity to build our market for the long term if each of us remembers two words, underwriting control," he said.

The opportunity comes from the "transitional state" of the world marine insurance market, said Mr. Beebe, who retired in July from Chubb & Son, Warren, N.J.

"The problems at Lloyd's of London have been the principal catalyst for change" and the "vacuum created by London's contraction is putting new demands on other world markets," he said. "The U.S. market is one of the beneficiaries. The playing field has leveled."

But he warned members they should rein in their field staff, most of whom have "never known anything but a soft market" where the goal was putting new risks of questionable quality on the books at whatever price.

"If an experienced underwriter can negotiate changes that he or she feels provide a reasonable certainty for profit, fine. If, on the other hand, no such certainty can be found, perhaps it's time to just say no."

Bo Wahloff, chairman of the International Union of Marine Insurance, said

hull rates were leveling out after two years of increases. Rather than pricing

hull coverage out of the reach of insureds, underwriters in London, Scandinavia and continental Europe next year will concentrate on increasing policy deductibles, he said.

"Shipowners are getting premium increases they can no longer afford," Mr. Wahloff said.

William Mack, vice chairman of the American International Marine Agency, a unit of American International Group, thanked marine underwriters for their efforts in getting the North American Free Trade Agreement passed Wednesday.

"We did go to work early during the entire process of negotiations to make sure the insurance parts of the financial services industry were represented," said Mr. Mack, who succeeded Mr. Beebe as AIMU chairman. The agreement "is a benefit to the U.S. and it is imperative to show we have a continued commitment to free trade."

Also at the meeting, Thomas J. Prendergast, chairman and president of MOAC, the marine unit of Continental Corp. in Cranbury, N.J., was elected vice chairman, succeeding Mr. Mack. Victor Yerrill, chairman and chief executive of GRE Insurance Group, New York, was elected treasurer.

Walter M. Kramer, vice president of the institute, was elected to succeed Ward L. Mauck, who retired as president after 10 years with the AIMU.