Longitudinal strength of high block coefficient merchant ships in irregular waves

Abstract

In this work, a method is developed to calculate the instantaneous shear force and bending moment of the ship in waves using point clouds. The force at each station is calculated by computing the hydrostatic and hydrodynamic pressure at each panel and the area of each panel at that station. This gives the variation of hydrostatic and hydrodynamic force in the vertical direction along the ship's length. The hydrostatic and hydrodynamic force acting on the ship is used to calculate the heave and pitch motion of the ship in waves. The weight distribution at each station is estimated by adding different components like lightship, cargo, machineries and outfit weight. The weight distribution is determined using the exact geometrical layout of the cargo/water ballast/fuel and fresh water tanks inside the ship. The longitudinal strength of a bulk carrier and Very Large Crude Carrier (VLCC) at zero forward speed in the head wave is investigated. The investigation shows that the shear force and bending moment of a ship can be accurately estimated using the proposed method. The bending moment in an irregular wave shows the Rayleigh distribution. One of the applications of this procedure is fatigue strength analysis of ships.