This paper proposes an evaluation method for operability of pleasure boats in order to develop an electronic control steering system of those boats. Based on usability as addressed by ISO 9241-11, some evaluation criteria such as effectiveness and efficiency are defined for a task of collision avoidance and course resuming. For safety and repeatability, the simulation with a simplified ship simulator, which is composed a manual hydraulic steering system as hardware in HILS, is performed instead of experiments. As a result of the simulation, it is found that the operability of the manual hydraulic steering system deteriorates in the case of emergency collision avoidance. In particular, the wakes of the course resuming after the emergency collision avoidance are caused to be periodic by wrong estimate of the normal pressure and by time delay in the dynamics of the pleasure boat. Therefore, it is found that the electronic control steering system of pleasure boats should have the functions to support estimation of the normal pressure and to compensate the time delay.
