Peter Waterman, 61, who retired in 1978 as special assistant for energy in the Office of the Assistant Secretary of the Navy, died of cancer Sunday at Georgetown University Hospital.

Dr. Waterman was an expert on weapons systems and served as a technical adviser to the director of the Polaris missile program, for which he received the second of five Navy distinguished civilian service awards in 1961.

He came here in 1943 to work for the Nval Research Laboratory as an engineer in the fire control branch and subsequently became chief of the equipment research branch.

In 1968, he was made a special assistant in the Office of the Assistant Secretary of the Navy for Research and Development and served as acting assistant secretary of the Navy for that division in 1973. He was appointed special assistant for energy and related matters in 1975. Dr. Waterman also served on a Presidential Domestic Policy Review Group on Solar Energy in 1978.

Following his retirement, he worked for the Westinghouse Defense and Electronic Systems Center in Annapolis.

Dr. Waterman was born in Hartford, Conn., and earned a bachelor of science degree in electrical engineering and a doctorate in engineering from the University of Vermont's engineering college.

During his 36-year federal career, Dr. Waterman received five navy distinguished civilian service awards, the first of which was accompanied by a $10,000 cash award, the Department of Defense distinguished civilian service award "for contributions to the Navy's offensive and defensive capabilities" and the Navy meritorious civilian service award.

He lived in Washington and was a member of the Washington Academy of Sciences and the American Defense prepardness Association.

Survivors include his wife, Kay, of the home; two sons, Paul, of Annapolis, and Philip, of Temple, N.H.; a daughter, Nancy, of Castleton, Vt.; a sister, Helen, of Jekyll Island, Ga., and four grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Dancer Society or to the Washington Animal Rescue League.