Pintle and 'gudgeon' rudder system.
Source: Based upon Lawrence V. Mott, The Development of the Rudder, A.D. 100-1600: A Technological Tale, Thesis May 1991, Texas A&M University (p. 83, Fig. 7.2). http://en.wiktionary.org/wiki/File:Pintle_and_gudgeon_rudder_system_scheme.svg
Author: Eric Gaba (Sting)