The Maritime Administration made the Bahamian flag the fourth under which U.S. shipowners may place their vessels and still have a chance to get emergency insurance coverage from the United States.

Whether they get it will depend on their willingness to make their ships available to the United States in emergencies and whether the particular vessel is of a type considered needed by the U.S. Navy.Panama, Liberia and Honduras have long been the flags recognized for the extension of these war-risk insurance commitments intended to take over upon the outbreak of hostilities between the major powers when commercial insurance is canceled.

The Bahamas altered its laws in 1983 to allow vessels registered there to be made available in emergencies to a foreign country. It also tightened its vessel safety standards.

In view of those changes, the Navy last year asked Marad to alter its regulations so U.S.-owned or U.S.-controlled vessels of the appropriate types under Bahamian flag could be made eligible for war-risk coverage and thereby available in emergencies.

The move was supported by the Federation of American Controlled Shipping, representing the U.S. owners of the vessels under the other three flags, Chevron, a U.S. operator of foreign tankers and the Republic of Vanuatu, another aspiring flag of registry country in the Pacific.

Vanuatu wanted its U.S.-owned ships included and the federation urged a wide extension of eligibility to larger tankers and bulk carriers as well as passenger ships.

Marad said it couldn't consider Vanuatu's request as part of the Bahamian case.

As for extending the type of ships eligible as the federation requested, Marad declined to do so. It cited a Congressional amendment, approved a decade ago, binding the agency to the present categories and reduce their number to some 340 of which only nine now are foreign flag.

There are 26 U.S.-owned or controlled ships now under the Bahamian flag. Marad indicatedthat 17 of them were types that would be eligible for the war- risk protection.

Full details of Marad's changes in regulations were expected to be published in the Federal Register, possibly today.