A steering control system for a watercraft includes a pivoting steering tiller manually operated and operatively connected to a direction changing member acting on or into the water, such as a rudder blade or an outboard motor; and a system locking the steering tiller in the steering position, which can be activated for keeping the tiller in a predetermined pivoting position and deactivated for allowing the tiller to be moved in a pivoting position to carry out a change in direction. According to the invention the locking system is switchable by way of switching actuators that are controlled by a control member provided on the arm.