Rudder

From Kayak Wiki

A rudder is a device used to steer a kayak. This is usually a metal plate that hangs off the stern of the kayak and is operated (left or right) by foot control. There should be a way of raising and lowering the ruder without getting out of the boat. If fitted to your sea kayak it would be good practice to paddle with the rudder disabled. Remember if you have a rudder fitted to pack appropriate spares in your repair kit. [by Richard Cree, Ocean Paddler Magazine - Issue 008]