The purpose of this paper is to analyse the problem of ship steering and to discuss qualitatively the problems associated with variations of the process dynamics and the disturbances. The paper is based on simple models which can be dealt with analytically. It serves as a complement to computer studies using more elaborate models. Models for ship steering dynamics and for disturbances due to wind and waves are reviewed. Criteria for ship steering and autopilot design are discussed. The performance of fixed gain autopilots under different operating conditions is analysed. It is shown that there is a good incentive for using adaptive autopilots.