Karl signed for the club from Warrington Town shortly after Nick Armitage took over as manager, and made his debut in December 2007 at Heswall.
A tall and commanding keeper with good shot stopping ability, Karl has played over 125 games for the club with an impressive clean sheet record of one every three games.
Earlier in his career he was at Crewe Alexandra where he played for the first team in the Football League, but an injury cut short his professional career.