2.2 Guidance for required trials and validation
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.1053 – Explanatory Notes to the Standards for Ship Manoeuvrability – (Adopted on 16 December 2002) - Annex - Explanatory Notes to the Standards for Ship Manoeuvrability - Chapter 2 - Guidelines for the Application of the Standards - 2.2 Guidance for required trials and validation

2.2 Guidance for required trials and validation

Parent topic: Chapter 2 - Guidelines for the Application of the Standards

2.2.1 Test procedures footnote

2.2.1.1 General

 The test procedures given in the following guidelines were established to support the application of the manoeuvring standards by providing to shipyards and other institutions standard procedures for the testing trials of new ships, or for later trials made to supplement data on manoeuvrability. This guidance includes trial procedures that need to be performed in order to provide sufficient data for assessing ship manoeuvring behaviour against the defined criteria.

2.2.1.2 Test conditions

2.2.1.2.1 Environment

 Manoeuvring trials should be performed in the calmest possible weather conditions. The geographical position of the trial is preferably in a deep sea, sheltered area where accurate positioning fixing is possible. Trials should be conducted in conditions within the following limits:

  • .1 Deep unrestricted water: more than 4 times the mean draught.

  • .2 Wind: not to exceed Beaufort 5.

  • .3 Waves: not to exceed sea state 4.

  • .4 Current: uniform only.

 Correction may need to be applied to the test results following the guidance contained in 3.4.2.

2.2.1.2.2 Loading

 The ship should preferably be loaded to the full load draught and even keel, however, a 5% deviation from that draught may be allowed.

 Alternatively, the ship may be in a ballast condition with a minimum of trim, and sufficient propeller immersion.

2.2.1.2.3 Ship speed

 The test speed is defined in paragraph 4.2.1 of the Standards.

2.2.1.2.4 Heading

 Preferably head to the wind during the approach run.

2.2.1.2.5 Engine

 Engine control setting to be kept constant during the trial if not otherwise stated in following procedures.

2.2.1.2.6 Approach run

 The above-mentioned conditions must be fulfilled for at least two minutes preceding the test. The ship is running at test speed up wind with minimum rudder to keep its course.

2.2.1.3 Turning circle manoeuvre

 Trials shall be made to port and to starboard using maximum rudder angle without changing engine control setting from the initial speed. The following general procedure is recommended:

  • .1 The ship is brought to a steady course and speed according to the specific approach condition.

  • .2 The recording of data starts.

  • .3 The manoeuvre is started by ordering the rudder to the maximum rudder angle. Rudder and engine controls are kept constant during the turn.

  • .4 The turn continues until 360° change of heading has been completed. It is, however, recommended that in order to fully assess environmental effects a 720° turn be completed (3.4.2 refers).

  • .5 Recording of data is stopped and the manoeuvre is terminated.

2.2.1.4 Zig-zag manoeuvre

 The given rudder and change of heading angle for the following procedure is 10°. This value can be replaced for alternative or combined zig-zag manoeuvres by other angles such as 20° for the other required zig-zag test. Trials should be made to both port and starboard. The following general procedure is recommended:

  • .1 The ship is brought to a steady course and speed according to the specific approach condition.

  • .2 The recording of data starts.

  • .3 The rudder is ordered to 10° to starboard/port.

  • .4 When the heading has changed by 10° off the base course, the rudder is shifted to 10° to port/starboard. The ship’s yaw will be checked and a turn in the opposite direction (port/starboard) will begin. The ship will continue in the turn and the original heading will be crossed.

  • .5 When the heading is 10° port/starboard off the base course, the rudder is reversed as before.

  • .6 The procedure is repeated until the ship heading has passed the base course no less than two times.

  • .7 Recording of data is stopped and the manoeuvre is terminated.

2.2.1.5 Stopping test

 Full astern is applied and the rudder maintained at midship throughout this test. The following general procedure is recommended:

  • .1 The ship is brought to a steady course and speed according to the specific approach condition.

  • .2 The recording of data starts.

  • .3 The manoeuvre is started by giving a stop order. The full astern engine order is applied.

  • .4 Data recording stops and the manoeuvre is terminated when the ship is stopped dead in the water.

2.2.2 Recording

 For each trial, a summary of the principal manoeuvring information should be provided in order to assess the behaviour of the ship. Continuous recording of data should be either manual or automatic using analogue or digital acquisition units. In case of manual recording, a regular sound/light signal for synchronization is advisable.

2.2.2.1 Ship's particulars

 Prior to trials, draughts forward and aft should be read in order to calculate displacement, longitudinal centre of gravity, draughts and metacentric height. In addition the geometry, projected areas and steering particulars should be known. The disposition of the engine, propeller, rudder, thrusters and other device characteristics should be stated with operating condition.

2.2.2.2 Environment

 The following environmental data should be recorded before each trial:

  • .1 Water depth.

  • .2 Waves: The sea state should be noted. If there is a swell, note period and direction.

  • .3 Current: The trials should be conducted in a well surveyed area and the condition of the current noted from relevant hydrographic data. Correlation should be made with the tide.

  • .4 Weather: Weather conditions, including visibility, should be observed and noted.

2.2.2.3 Trial related data

 The following data as applicable for each test should be measured and recorded during each test at appropriate intervals of not more than 20 s:

  • Position
  • Heading
  • Speed
  • Rudder angle and rate of movement
  • Propeller speed of revolution
  • Propeller pitch
  • Wind speed

A time signal should be provided for the synchronization of all recordings. Specific events should be timed, such as trial starting-point, engine/helm change, significant changes in any parameter such as crossing ship course, rudder to zero or engine reversal in operating condition such as ship speed and shaft/propeller direction.

2.2.2.4 Presentation of data

 The recordings should be analysed to give plots and values for significant parameters of the trial. Sample recording forms are given in appendix 6. The manoeuvring criteria of the Standards should be evaluated from these values.

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