Following investigations into drift characteristics, it was discovered that results obtained for VLCCs were not necessarily indicative of the behaviour of smaller vessels. Concern was expressed by the American Institute of Merchant Shipping (AIMS) for the need to include within the scope of the studies details for vessels of the 50,000 to 70,000 dwt range, particularly in view of the present numbers of these ships.
Computer programs were developed by the National Maritime Institute (NMI) to assess drift behaviour of these ships, which required validation. Some free model experiments were carried out to investigate wave drift forces and also to determine the accuracy of results obtained.
OCIMF and the NMI worked together to estimate the effects of wind, waves and current upon the drift track, heading and speed of such vessels under a variety of conditions.
The Appendix to the study contains some 28 of the 72 runs, being representative of the whole series or effects obtained.