7.2 Definitions
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Statutory Documents - IMO Publications and Documents - International Codes - Intact Stability (IS) Code - Intact Stability for All Types of Ships Covered by IMO Instruments – Resolution A.749(18) - Annex - Code on Intact Stability for all Types of Ships Covered by IMO Instruments - Chapter 7 - Determination of Lightship Displacement and Centres of Gravity - 7.2 Definitions

7.2 Definitions

 For the purpose of this chapter, unless expressly provided otherwise:

  7.2.1 Certification of the test weights is the verification of the weight marked on a test weight. Test weights should be certified using a certificated scale. The weighting should be performed close enough in time to the inclining test to ensure the measured weight is accurate.

  7.2.2 Draught is the vertical distance from the moulded baseline to the waterline.

  7.2.3 The inclining test involves moving a series of known weights, normally in the transverse direction, and then measuring the resulting change in the equilibrium heel angle of the ship. By using this information and applying basic naval architecture principles, the ship's vertical centre of gravity (VCG) is determined.

  7.2.4 Lightship condition is a ship complete in all respects, but without consumables, stores, cargo, crew and effects, and without any liquids on board except that machinery and piping fluids, such as lubricants and hydraulics, are at operating levels.

  7.2.5 A lightweight survey involves taking an audit of all items which should be added, deducted or relocated on the ship at the time of the inclining test so that the observed condition of the ship can be adjusted to the lightship condition. The weight, longitudinal, transverse and vertical location of each item should be accurately determined and recorded. Using this information, the static waterline of the ship at the time of the inclining test as determined from measuring the freeboard or verified draught marks of the ship, the ship's hydrostatic data, and the sea water density, the lightship displacement and longitudinal centre of gravity (LCG) can be obtained. The transverse centre of gravity (TCG) may also be determined for mobile offshore drilling units (MODUs) and other ships which are asymmetrical about the centreline or whose internal arrangement or outfitting is such that an inherent list may develop from off-centre weight.


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