In the fall of 1944, Tunnell played at the halfback position for the San Francisco Coast Guard Pilots football team. On November 11, 1944, he led the Pilots to a 13–0 victory over Amos Alonzo Stagg's Pacific Tigers football team, throwing 22 yards for a touchdowns and returning an interception 75 yards for another touchdown. At the end of the 1944 season, he was named to the All-Pacific Coast service football team. He also played basketball for the San Francisco Coast Guard, scoring 13 points in a December 1944 game against the California Golden Bears.