Article 16 Stability
Every vessel of 12 metres in length and over to which these Rules apply shall in all operating conditions and circumstances set out in paragraphs 10 and 11 of Schedule 3 to these Rules and in all foreseeable operating conditions satisfy the following stability criteria after due correction for the free surface effects of liquids in tanks:—
the area under the curve of righting levers (GZ curve) shall not be less than:—
0.055 metre-radians up to an angle of 30 degrees;
0.090 metre-radians up to an angle of 40 degrees or such lesser angle of heel at which the lower edges of any openings in the hull, superstructures, deckhouses or companionways, being openings which cannot be closed weathertight, are immersed;
0.030 metre-radians between the angles of heel of 30 degrees and 40 degrees or such lesser angle as defined in (ii) above;
the righting lever (GZ) shall be at least 0.20 metres at an angle of heel equal to or greater than 30 degrees;
the maximum righting lever (GZ) shall occur at an angle of heel not less than 25 degrees;
in the upright position the transverse metacentric height (GM) shall not be less than 0.35 metres;
provided that, for vessels engaged on single or twin boom fishing the values of dynamic stability, righting lever and metacentric height given in sub-paragraphs (a), (b) and (d) respectively of this Rule shall be increased by 20%.