Graduated from the Naval Academy in 1938 after playing a valuable role in the establishment of the academy's ocean sailing program. Initial commissioned service was on board the heavy cruiser Chicago (CA-29) and the destroyer Rhind (DD-404), including combat duty in the Atlantic. After Submarine School, was executive officer of the submarine Barb (SS-220) under skipper Gene Fluckey. Following postgraduate work in ordnance engineering at Massachusetts Institute of Technology, served 1947-49 in the large aircraft carrier Midway (CVB-41) and 1949-52 at the Naval Ordnance Laboratory at White Oak, Maryland. In the 1950's commanded the escort destroyer Taylor (DDE-468), served in the Bureau of Ordnance, and was a student at the Industrial College of the Armed Forces. Later commanded Destroyer Division 322, the Atlantic Fleet Anti-Submarine Warfare Tactical School, and Destroyer Squadron 25. At the Naval Academy in 1962-64 had a large role in revising the curriculum and hiring the first academic dean. Flag officer duties in the 1960's included being U.S. representative on the staff of Commander in Chief Allied Forces Mediterranean, Commander Cruiser-Destroyer Flotilla Four, and superintendent of the Naval Postgraduate School. In 1971-72 McNitt served as Assistant Deputy Chief of Naval Operations (Manpower and Training) and from 1972 to 1985 was the civilian dean of admissions at the Naval Academy.