2.1 Conditions at which the Standards apply

  2.1.1.1 Compliance with the manoeuvring criteria should be evaluated under the standard conditions in paragraph 5.2 of the Standards for ship manoeuvrability. The standard conditions provide a uniform and idealized basis against which the inherent manoeuvring performance of all ships may be assessed.

  2.1.1.2 The Standards cannot be used to evaluate directly manoeuvring performance under non-standard, but often realistic, conditions. The establishment of manoeuvrability standards for ships under different operating conditions is a complex task that deserves ongoing research.

 Manoeuvrability of a ship is strongly affected by interaction with the bottom of the waterway, banks and passing ships. Trials should therefore be conducted preferably in deep, unconfined but sheltered waters. The water depth should exceed four times the mean draught of the ship.

  2.1.3.1 The Standards apply to the full load and even keel condition. The term "fully loaded" refers to the situation where the ship is loaded to its summer load line draught (referred to hereafter as "full load draught"). This draught is chosen based on the general understanding that the poorest manoeuvring performance of a ship occurs at this draught. The full load draught, however, is not based on hydrodynamic considerations but rather statutory and classification society requirements for scantlings, freeboard and stability. The result being that the final full load draught might not be known or may be changed as a design develops.

  2.1.3.2 Where it is impractical to conduct trials at full load because of ship type, trials should be conducted as close to full load draught and zero trim as possible. Special attention should also be given to ensuring that sufficient propeller immersion exists in the trial condition.

  2.1.3.3 Where trials are conducted in conditions other than full load, manoeuvring characteristics should be predicted for trial and full load conditions using a reliable method (i.e. model tests or reliable computer simulation) that ensures satisfactory extrapolation of trial results to the full load condition. It rests with the designer/owner to demonstrate compliance at the final full load condition.

 The Standards apply to a situation where the ship is loaded to a reasonable and practicable metacentric height for which it is designed at the full load draught.

 Trials should be held in the calmest weather conditions possible. Wind, waves and current can significantly affect trial results, having a more pronounced effect on smaller ships. The environmental conditions should be accurately recorded before and after trials so that corrections may be applied. Specific environmental guidelines are outlined in 2.2.1.2.1.

 The required test speed is defined in paragraph 4.2.1 of the Standards for ship manoeuvrability.