During ship design stage many calculations are made in order to define minimum metacentric height GMMIN values, which would meet all intact and damage stability criteria. Based on these values a set of curves can be prepared for relevant draught range. The limiting envelope curve presents minimum operational metacentric heights which meet all stability criteria for draught range from lightship draught to maximum draught. To obtain accurate guidance for stability of a ship it is enough to calculate the actual metacentric height GM corrected for free surface effects and check whether it is higher or equal to the required GMMIN value.
