The fiberglass Sunfish from 1960-1972 had a bronze rudder releasing mechanism that included hull plates, a spring plate and a vertical hinge. Hinge tension was adjusted by a carriage bolt that ran through a spring plate. The bolt went through the hull of the wooden Sunfish and it was shorter, so there was not much slop. On the fiberglass Sunfish the bolt was outside of the hull and longer, 7 inches, so some slop developed as the assembly became worn. On later 60s fiberglass Sunfish a nylon sleeve or tube was added to help hold the bolt vertical in the transom slot.