Abstract: A power steering system for outboard motors or inboard/outboard units for boats having a pivoted motor assembly so that by pivotation of the assembly the boat is steered, the system including a control rudder mounted aft of the motor assembly propeller, a steering member which is laterally displaced adjacent the motor assembly to steer the boat, a control rudder steering linkage extending from the control rudder to the steering member so that when the steering member is laterally displaced the control rudder is displaced to apply torque to the motor assembly to rotate it and thereby apply steering force to the motor assembly, a lockable slip between the steering member and the motor assembly which, in the locked condition, the steering member is secured to the motor and in the unlocked condition a preselected amount of slip is provided between the steering member and the motor assembly, apparatus for detecting the speed of the boat forward movement connected to actuate the lockable slip to lock the steering m