2.6 Control of stability, trim and longitudinal strength
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.920 – Model Loading and Stability Manual – (15 June 1999) - Annex – Model Loading and Stability Manual - Section 2 – Guidance to the master - 2.6 Control of stability, trim and longitudinal strength

2.6 Control of stability, trim and longitudinal strength

  2.6.1 Reference to the ship's approved loading and stability computer should be made and to the user guide provided with this computer, if applicable.

  2.6.2 A simple guidance should be given for the manual calculation of stability, draught and trim, which may be required for the control of loading conditions outside the scope of conditions under 2.5 on ships not equipped with an approved loading and stability computer, or if such computer fails. The use of suitable form sheets is recommended for this purpose.

  2.6.3 This subsection should, if appropriate, present the following form sheets for:

  • .1 compiling mass and position of consumables and stores;

  • .2 compiling mass and position of ballast;

  • .3 compiling mass and position of cargo;

  • .4 compiling mass and position of fishing gear;

  • .5 compiling mass and position of ice accretion;

  • .6 compiling displacement and position of centre of displacement and evaluating draught and trim; and

  • .7 plotting a righting lever curve and, where appropriate, a wind heeling lever curve.

  2.6.4 The form sheet under 2.6.3.3 should suit the particular type or types of cargo the ship is intended to carry, i.e. a different layout may be required for:

  • .1 break bulk;

  • .2 containers;

  • .3 ro/ro-vehicles;

  • .4 bulk cargoes (solid or liquid);

  • .5 fish; and

  • .6 ice.

 For cargoes with a structured stowage pattern like containers or ro/ro-vehicles, separate form sheets for calculating the vertical and the longitudinal position of the centre of cargo mass may be useful.

  2.6.5 A model of the form sheets under 2.6.3.4 and 2.6.3.5 is shown in the tables 2 and 3 below.

Table 2 Form for evaluating displacement, draughts and stability

Table 3 Form for calculating and plotting the righting lever curve (the GZ-axis may be expanded is necessary)

  2.6.6 One calculated example should be provided together with explanatory comments. A note should be given that in calculating a loading condition, at least one (or pair of) fuel and fresh water tank should be considered slack.

  2.6.7 If the ship is equipped with an approved installation for performing in-service inclining tests, a reference note should be given to the operations manual of this equipment, or, if deemed appropriate, comprehensive guidance placed in this subsection.

 If, on request by the owner, the loading and stability manual is to contain additional technical information for supporting a draught survey or other stability management issues, appropriate guidance and calculated examples should be given in this subsection. The Guidelines on the management of ship's stability, to be developed by the Organization, should be taken into account, if appropriate.


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