Manoeuvring criteria - more than IMO A751 requirements alone!

In 1993, IMO resolution A751(18) was accepted. Since 1993, ship designs focussed on complying with these standards. For the Netherlands, MARIN gathered the full-scale results of about 100 ships. Performance with respect to IMO A751 requirements was demonstrated in the 2002 meeting of the IMO-DE. It was shown that most ships fulfilled the IMO recommendations. The ships not fulfilling the requirements sailed anyway, manually, or by using an advanced autopilot. Based on the gathered manoeuvring properties of the vessels, the following observations are made. The current standards are focussing much on conventional vessels: displacement ships propelled by standard propulsions (propeller(s) and rudder(s)). For vessels with other propulsion means, the rules are flexible. Also sailing in shallow and restricted water (most critical manoeuvring situations) are not dealt with. The impact of environment (wind, waves and other vessels) is also not taken into account. Because there are no criteria for that, under the economic pressure ships will be constructed “just” fulfilling the design criteria (so-called fit-for-purpose). However, other aspects are also important. On these subjects a set of criteria is proposed and ways to test or verify the designs are discussed.