John M. Drewry, 66, former chief counsel of the House Merchant Marine and Fisheries Committee, died of a heart ailment Wednesday at Alexandria Hospital.

Mr. Drewry joined the Committee staff in 1949 and served as its chief counsel from 1956 until retiring in 1969.

During his years with the Committee he helped establish the Oceanography Subcommittee in 1959, worked on the sea grant program that was established in 1966, and worked for the creation of the Marine Siences Council.

He began his government career as a legal counsel with the U.S. Maritime Commission, where he worked from 1939 to 1947.

After leaving government service in 1969, he entered private law practice and acted as counsel to the National Ocean Industries Association until he retired in January, 1977.

Mr. Drewry was born in Petersburg, Va., and earned a bachelor's degree from Randolph-Macon College and a law degree from the University of Virginia.

He practiced law in New York City before moving here in 1939.

He was past president of the Washington Propeller Club and belonged to the Marine Technology Society and several bar associations.

Mr. Drewry is survived by his wife, Judith, and a daughter, Julianne, of the home in Alexandria; another daughter, Patricia D. Sanger, of Virginia Beach; two sons, John T., of Silver Spring and James S.W., of Washington, and five grandchildren.