Peter Nathaniel Sherrill, 70, a Navy officer and polling company executive who co-founded a software company. Sherrill, who was raised in San Marino, graduated from the Naval Academy and served in the Korean War as a captain of the minesweeper Lark and aboard the troop transport Breckenridge at the Inchon landing. After his naval career, Sherrill worked for Hewlett-Packard and later West Associates and earned a doctorate at Stanford University. From 1967 to 1987, he was vice president and technical director of the pioneering Field Research Corp. and Field Institute, which operate the Field Poll. In 1983, Sherrill co-founded SL Corp., a computer software company in Corte Madera, Calif., that specializes in object-oriented tools for graphics programmers and researchers. Also active in supporting the arts, Sherrill served on the boards of the San Francisco Museum of Modern Art and the San Francisco Ballet. On April 9 in Sausalito.