From December 2004 onwards every seagoing vessel over 300 Gross Tonnage (GT) is obliged to be equiped with an Automatic Identification System (AIS). Vessels equipped with this system, send out a message every few seconds, containing their position, speed, course, identification number, etc. This makes it possible to perform a statistical analysis of vessel behaviour, based on these AIS messages. If in this way more insight in the vessel behaviour is obtained, maritime models might benefit. In this thesis such an analysis is done, by a case study in the Port of Rotterdam area. The average vessel path and accompanying vessel speed are investigated. The influence of vessel size, wind, current and visibility on the path and speed are taken into account as well. In the end, these results are generalised, so they can be used for other port areas as well.