A judo expert, he served as a chief fitness instructor in the Navy from 1942 to 1946 at United States Naval Training Center Bainbridge, Maryland and Staten Island during World War II.

He was the third base umpire during Don Larsen's perfect game for the New York Yankees against the Brooklyn Dodgers in the 1956 Series,[3] and was at first base for Catfish Hunter's perfect game for the Oakland Athletics against the Minnesota Twins on May 8, 1968.

Napp was also the home plate umpire for Early Wynn's 300th career victory,[9] as well as Denny McLain's 30th victory of the 1968 season (September 14),[10] the last time to date that a pitcher has won 30 games during a regular season.

Tiger Stadium had been utilizing a sniper with a pellet gun behind home plate for part of that season.

[12] Prior to the 1962 season, he moved from his long-time home of Staten Island to Plantation, Florida.