The Navy said yesterday that it will conduct an in-depth study between now and August of alternatives to the Trident missile submarine and 688 class attack submarine in hopes of finding ones "that might significantly reduce costs."

Navy Secretary W. Graham Claytor ordered the study, the Navy said. It will be under the direction of David Mann, assistant Navy secretary for research. Fred Payne, now an Aerospace executive who directed the Start X study of strategic options in the 1960s, has been called back to the Pentagon temporarily to head the Navy submarine analysis.

The Senate Armed Services Committee has directed the Navy to conduct a study of submarine alternatives and approved $16 million for the effort.

Payne, who worked with Defense Secretary Harold Brown in the early 1960s when Brown was Pentagon research director, was chosen to give the study team independence from Navy submarine leaders who have resisted alternatives to the Trident and 688 class subs, sources said.

The first Trident submarine is running a year behind schedule and 50 percent over its estimated $800 million cost. Critics have argued that a Trident costing $1.5 billion will price itself out of the Navy fleet. The 688 class sub costs $257.6 million. Both subs are nuclear powered.

The study panel is expected to take a hard look at smaller, cheaper nuclear powered subs which would be harder to detect. However, to the disappointment of some undersea warfare specialists, the study will not consider non-nuclear alternatives, sources said.