2.2 Terms, symbols and units
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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 - 2.2 Terms, symbols and units

2.2 Terms, symbols and units

  2.2.1 It is of utmost importance for the practical use of the manual by the mariner that terms, symbols and units comply with relevant ISO standards.footnote A statement of this compliance should be given in this section.

  2.2.2 The terms, symbols and units considered necessary in a typical loading and stability manual are shown in table 1. Sketches, such as shown in figures 1, 2 and 3, depicting the above symbols, should be included in the manual as deemed appropriate.

Table 1 Terms, symbols and units

Term Symbols used SI-unit
After perpendicular AP –
Fore perpendicular FP –
Mid between perpendiculars MP –
Baseline BL –
Bottom of keel BK –
Heel angle N rad; (°)
Length (usually Lpp for merchant ships) L m
Breadth B m
Depth D m
Freeboard f m
Keel draught TK m
Aft keel draught TKA m
Keel draught, reading at aft draught mark TKAR m
Reference keel draught TKC m
Forward keel draught TKF m
Keel draught, reading at forward draught mark TKFR m
Mean keel draught = 0.5 (TKA + TKF) TKM m
Keel draught, reading at mid draught mark TKR m
Hull deflection = TKM - TK d m
Trim = TKF - TKA t m
Displacement volume L; DISV m3
Displacement mass ); DISM kg; (t)
Displacement mass per centimetre change of draught TPC kg/cm; (t/cm)
Waterplane area coefficient CWP –
x - co-ordinate of centre of buoyancy xB;XB m
x - co-ordinate of centre of flotation xF;XF m
x - co-ordinate of centre of gravity xG;XG m
y - co-ordinate of centre of gravity xG;YG m
z - co-ordinate of centre of gravity KG m
Corrected z - co-ordinate of centre of gravity = KG + )KG KGc m
z - co-ordinate of metacentre KM m
Metacentric height GM m
Corrected metacentric height = GM - )KG GMc m
Righting lever GZ m
Value of stability cross curve 1K; LK m
Heeling lever of lateral wind force 1v; LV m
Transverse moment of inertia of the surface of liquids iB;IB m4
Moment to change trim one centimetre MTC Nm/cm; (tm/cm)
Moment to change trim one metre MTM Nm/m; (tm/m)
Natural roll period TN s
Rolling coefficient CN –
Wind pressure pv N/m2
Ship's speed V m/s; (kn)
x - co-ordinate of aft draught mark – m
x - co-ordinate of mid draught mark – m
x - co-ordinate of fore draught mark – m
Density SI-symbol: D kg/m3; (t/m3)

Figure 3

Parent topic: Section 2 – Guidance to the master
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