Johan L. Isaksen, 60, a retired structural draftsman and a former master machinist at the old Washington Navy Yard, died of congestive heart failure Sunday at his home in Oxon Hill.

Mr. Isaksen had been a volunteer in recent years with Mended Hearts Inc., an organization that helps patients facing heart surgery. He also had been a supporter of the Prince George's County Ballet Company and a member of St. Barnabas Episcopal Church in Temple Hills.

A native of Washington, Mr. Isaksen was a graduate of Eastern High School. He went to work for the Navy Yard in 1942 and remained there until 1954, when he retired because of rheumatic fever.

He then became a structural draftsman. From 1955 until about 1970, he worked for Beall & LeMay, a structural engineering firm in Washington. He later worked for Mills & Petticord.From 1972 until 1978, when he retired, he did structural drafting on a free-lance basis.

In 1978, he received an award from the Consulting Engineers Council of Washington for his work.

Survivors include his wife, Rhettalou, of Oxon Hill, where Mr. Isaksen lived; two daughters, Gloria, of Oxon Hill, and Bonnie, of Fredericksburg, Va., and two brothers, Walter, of Arlington, and Donald of Upper Marlboro.