When an American-owned coal ship capsized off the Virginia coast last month the 34 crew members had no chance to put on protective suits that might have kept them alive in the frigid water.

The ship was not required to have the suits on board. The absence of the rubberlike insulating garb, long advocated by federal safety officials, has reawakened old concerns.

"If they had been wearing exposure suits, they may have survived long enough for people to rescue them," said Ralph E. Johnson, a National Transportation Safety Board investigator, after the accident.

Paul C. Dewey, one of only three survivors from the ship, also raised the issue at a federal fact-finding hearing. "With survival suits, a lot more people would have been saved," he testified.

Exposure suits have been under review by U.S. officials since the mid-1970s. Deciding whether to require them on seagoing vessels has taken time, officials say, partly because the issue is entangled in international maritime talks. In addition, they say, new equipment, such as the suits, demands special study.

Just nine days before the accident, the Coast Guard had proposed a rule that eventually would require exposure suits on many oceangoing vessels and offshore oil rigs.

"Unfortunately, we weren't on time to save Marine Electric," said Coast Guard survival chief Robert Markle. The 605-foot Marine Electric capsized before dawn Feb. 12 about 30 miles east of Chincoteague.

The reddish-orange suits, frequently made of a synthetic rubberlike foam called neoprene, are designed to offer protection from cold water and frigid air for six or more hours--often long enough for rescue workers to arrive. Air pockets in the foam act as insulators and provide buoyancy. Without such protection, a sailor thrown overboard may die after only minutes in near-freezing water because of hypothermia, or the loss of body heat.

Exposure suits have repeatedly been promoted by safety officials after investigations of cold-water catastrophes, including the 1975 sinking of the ore-carrying vessel Edmund Fitzgerald in the Great Lakes and last year's capsizing of the oil-rig Ocean Ranger off Newfoundland.

More then four years after the Edmund Fitzgerald's 29 crew members died, the Coast Guard required exposure suits on vessels plying the Great Lakes. Five months after 84 workers on the Ocean Ranger died, the Coast Guard announced that it would draft new rules requiring the suits on offshore oil rigs. Because rescuers were nearby, some of these victims probably would have survived if exposure suits had been on board, federal officials say.

The Coast Guard regulations, proposed Feb. 3, appear likely to stir further debate.

Safety board officials object to a provision that would let vessels continue operating without exposure suits if they carry special lifeboats enclosed by canopies. Crew members could still be flung into the water if an enclosed lifeboat capsizes or other mishaps occur, board aides contend.

"The Ocean Ranger proved this," said Luigi A. Colucciello, the board's marine accident chief.

Another controversial provision would exempt vessels traveling as far north as the Virginia coast. Although the exemption is designed to apply to ships operating in warm waters, some advocates of exposure suits describe the proposal as too lax.

"The Marine Electric was south of the Virginia coast," argued Sue Forbes, president of BayleySuit Inc., a California-based company that makes the suits.

Coast Guard officials say the proposed regulations were modeled, in part, on recently drafted revisions of the 1974 Safety of Life at Sea Convention, an international treaty now under review in London by the International Maritime Organization, a U.N. affiliate. Delays in drawing up the Coast Guard proposal stemmed in part from concern about possible conflicts with the international accord, officials say.

Exposure suits, which now sell for about $250 to $300 each, are already in widespread use in the American fishing industry as well as in Canada and Norway, according to industry officials. Two major U.S. manufacturers, Imperial Manufacturing Co. Inc. and BayleySuit, say they have sold 80,000 suits.

The proposed rules, expected to cost the shipping and oil-rig industries nearly $14 million, have prompted only limited opposition so far from industry groups.

"You're immediately cast in the role of being against motherhood," complained one opponent, William Mayberry, executive director of the New Orleans-based Offshore Marine Service Association. Mayberry, whose group represents vessels that service oil rigs, argued that the suits "have very little shelf life" and that their cost is burdensome.

One alleged flaw surfaced in December, when Rep. Albert Gore Jr. (D-Tenn.) charged that the Federal Trade Commission had failed to act on a "life-threatening defect" in BayleySuit equipment. The firm disputed the charges and said it voluntarily offered a kit to make any necessary repairs.