Retired Navy Capt. Horatio Clay Sexton, 81, an expert on submarine design and mine warfare, died Tuesday at Anne Arundel General Hospital of a cardioarterial ailment.

Capt. Sexton, a native of Rushville, Ind., graduated in 1919 from the U.S. Naval Academy. In 1923, he earned a degree in naval architecture from the Massachusetts Institute of Technology. He then taught at the Naval Academy, and was coauthor of one of the first textbooks on aerodynamics, published in 1926.

During both World Wars he was involved in the engineering, design and construction of submarines.

Toward the end of World War II, Capt. Sexton directed the mine-sweeping division of the bureau of ships here. He retired in 1950.

Capt. Sexton then taught the history of naval warfare and warship design at MIT's naval graduate school until 1953, when he joined the Central Intelligence Agency as a senior naval analyst. He retired a second time in 1961.

Among his military honors were the Legion of Merit and the Order of the British Empire.

Survivors include his wife, the former Ruth Montgomery, of the home in Annapolis; a daughter, Mary Susan Brooks, of Westport, Conn.; two sons, John M., of Baltimore, and Horatio C., also of Annapolis, and eight grandchildren.