Several sources state that 70 to 80 percent of maritime accidents are caused by human error. Technical improvement in vessel design or operational equipment generally contributes to more safety on board and to a decrease of accidents in the maritime field. As a result, the contribution of human errors as one of the causes of maritime accidents relatively increases. The human factor is not negligible in complex manoeuvres. To study the human factor in a maritime environment is possible in several ways. A manoeuvring simulator provides a quite realistic setting in which it is possible to study for example workload and performance in relation to task demand. At MARIN any combination of two full mission bridges and four additional cubicles makes it possible to simulate nautical operations in applications like nautical research into new harbour and fairway layouts or the development (and training) of operational procedures. Human factor aspects like workload and performance measured during these simulator runs provide (objective) feedback to human behaviour.