In 1981 the "Stichting Coordinatie Maritie? Onderzoek" ordered the first part of a research program concerning thrusters and station keeping. This work has been continued in subsequent years covering such topics as thrusterlthruster interaction, thrusterlhull interaction, environmental forces and low frequency motions. This resulted in a time-domain simulation program, DPSIM. To validate this program dynamic positioning model tests were performed for a number of conditions. The measured and calculated results show adequate agreement.