“…Today, the modern theory about it is set in the bifurcation/catastrophe/singularity theory by Thom, [16], Zeeman, [16], Poston and Stewart, [18], and Arnold, [19], as a part of singularity theory, and control theory also. Recently, theoretical aspects of metacentric curve role in the evaluation of ship's stability are examined in the works of Mégel and Kliava, [20], Spyrou, [21], and many others, with the need for analytical examination of it for two-dimensional and three-dimensional problems for regular cross section shapes and bodies, like in recent quadratic approximation of centre of buoyancy curve for trapezoidal and pentagonal cross section in the work of Smirnov and Khashba, [22], or practical applications for general ship geometry and hydrostatics determination like in, [23], [24] and [25]. In general, regarding ship stability calculations, the goal is observing centre of buoyancy B-curve and its evolute M-curve for heel angles range from 0°to 90°.…”