After the introduction of Fast Ferry public transport in the Netherlands a number of complaints about wake wash induced hindrance onboard moored vessels appeared. It was already possible to calculate the wake wash characteristics of fast sailing vessels, the progress of these waves in a waterway and their effect on moored vessels. This paper describes the full scale tests carried out to develop the missing relation between the wash induced motions of a moored vessel and the hindrance thereof. (...) A guideline for maximum ship motions is developed from the results. With this guideline, it can be determined prior to the introduction of a new innovative vessel with reasonable accuracy if its wake wash will remain within acceptable limits.