Backers of building smaller war-ships and submarines at the expense of the nuclear giants received an assist yesterday from the Atlantic Council, a nonprofit study group.

Western nations should "avoid the tendency to base their navies primarily on a small number of expensive vessels subject to damage or loss, such as supercarriers and cruisers," the council said in releasing a summary of its two-year study on how best to combat the Soviet naval threat.

Since modern weaponry enables an attacker to find and damage ships, the council report said, "what may appear to be an economy of scale during peacetime could turn out to be the folly of putting too many eggs in one basket during wartime, even in a local intervention operation."

President Carter was so dead set against building another $2 billion Nimitz class nuclear-power aircraft carrier that, earlier this year, he voted the defense money bill authorizing its construction.

The battle of quality vs. quantity will be fought against next year as Congress reviews the Navy's fiscal 1980 shipbuilding budget. The Nimitz aircraft carrier and giant Trident missile submarine are at the heart of the shipbuilding controversy.

The council has turned its study into a book entitled "Securing the Seas: Soviet Naval Challenge and Western Alliance Options" to be published in January. the study group was headed by Paul H. Nitze, former deputy secretary of defense.

The summary of the study released yesterday also recommended that the Navy reassess any war plans that call for ordering ships from the Pacific to fight a North Atlantic Treaty Organization war in the Atlantic; that the United States spend at least $10 billion a year on shipbuilding and NATO allies $6 billion, that NATO nations build their cargo ships to accommodate armament in wartime and that some of those ships be small one, and that NATO deploy more antisubmarine mines like the U.S. Navy's Captor.