Module 31Function 1: Marine Engineering at the Management Level1.1.6Naval Architecture and Ship Construction Including Damage Control
Module 32Function 1: Marine Engineering at the Management LevelCenter of Gravity (G): that point at which all the vertically downward forces of weight of the vessel can be considered to act; or it is the center of the mass of the vessel. 6.1Basic Stability and TrimG is the resultant of all vertical downward forces of gravity
Module 33Function 1: Marine Engineering at the Management LevelCenter of Buoyancy (B):that point at which all the vertically upward forces support (buoyancy) can be considered to act; or, it is the center of the volume of the immersed portion of the vessel.B resultant of all vertical upward forces of buoyancyB is the center of gravity of the immersed portion of the vessel6.1Basic Stability and Trim
Module 34Function 1: Marine Engineering at the Management LevelTransverse Metacenter (MT):point through which the center of buoyancy (B), acts vertically upwards as the vessel is inclined and (B) shifts towards the low side.The same displacement; the same angle of inclination but G moves, transverse metacenter (M) and the equilibriums6.1Basic Stability and Trim
Module 35Function 1: Marine Engineering at the Management LevelMetacentric Height (GM):is the measure of the initial stability of a vessel or it is the vertical distance between the ship’s center of gravity and the initial transverse metacenter (M).GM as a Function of GZ6.1Basic Stability and Trim
Module 36Function 1: Marine Engineering at the Management Level6.1Basic Stability and TrimHeel (roll)is caused by external forces to the ship. - Ocean waves cause an external force on the ship that start the ship rolling and keep it rolling.Effects of Listing and HeelingListis caused by internal forces. - may have been created by poor loading policies, - by shift of cargo or ballast in heavy weather, or - by unsymmetrical flooding after damage.In any of these cases, the list will be attributed either to a negative initial stability (a negative GM) or a condition in which G is off the centerline. Either way, the ship will oscillate about this angle of list instead of about the vertical.
Module 37Function 1: Marine Engineering at the Management Level6.1Basic Stability and TrimIt merely means that the vessel does not have any initial stability, and that she will incline to an angle where B has moved far enough toward Dangers of a Ship Having Negative GMIf the center of gravity lies above the transverse metacenter(G above M), the vessel is in state of unstable equilibrium, that is, she possesses a negative GM. There is no tendency for the vessel to right herself at small angles of inclination.