Translations:FreeCAD-Ship s60 tutorial (II)/5/en

IMO (International Maritime Organization) set following criteria:
 * GM >= 0.15 m. GM (metacentric height) is the initial tangent of the GZ curve.
 * Maximum GZ value must be placed over 30 degrees of roll angle.
 * With 30 degrees roll angle, GZ value must be 0.2 m at least.
 * Area involved by GZ curve up to 40 degrees of roll angle must be at least 0.090 m · rad.
 * Area involved by GZ curve up to 30 degrees of roll angle must be at least 0.055 m · rad.
 * Area involved by GZ curve from 30 to 40 degrees of roll angle must be at least 0.030 m · rad.