Hydronav' 21 Sopot-Iława – online
International Symposium on Hydrodynamics in Ship Desing, Safety, Manoeuvring and Operation
Polski Rejestr Statków S.A., Gdańsk
Analysis of lifeboat emergency launching from a passenger ro-ro ferry during its motions in stochastic waves
According to the LSA-Code criterion 220.127.116.11 (resolution MSC.48(66)), each fully loaded lifeboat when launched should withstand a lateral impact against the ship's side at an impact velocity of at least 3.5 m/s. Therefore, it is particularly important to determine the impact velocity at which the launched lifeboat with people on board hits the ship's side. The motion of launched lifeboat, attached to davits which are moving along with the ro-ro ship and inducing the lifeboat motion, was modelled as a pendulum with uniformly increasing length of the ropes on which the boat is lowered. It was assumed that the ship motion is induced by stochastic beam seas. The numerical method was used to solve the differential equations describing the ship's motions in waves in the first step, and then, the motions of the pendulum induced by ship motions, in the second step. The numerical computations were performed for one loading condition and for four sea states. The purpose of this study is to determine the impact velocities at which the launched fully loaded lifeboat hits the ro-ro ship's side in the assumed sea states.
Keywords: LSA-Code, lifeboat, impact velocity, differential equations, ship motion, pendulum