SHIPMA relies on the use of an autopilot, which also includes a tug and thruster allocation algorithm. The choice for using an autopilot rather than hands-on steering by a pilot or Master allows the engineer to clearly judge and compare the results of different simulations on technical and physical aspects. The use of an automatic pilot in desktop simulation assures repeatability and a consistent nautical assessment procedure. The hands-on mode often seen in other models (actively steering the ship over a chart displayed on a screen) would put a civil engineer in a position where he is in fact playing the role of a pilot or Master. Alternatively, one could ask a pilot to do the runs, but the chart display offered to him is rather different from his normal sailing practice. This will jeopardise the result of the manoeuvres. Furthermore, runs have to be repeated to guarantee consistency.