Computational Model for Simulation of Lifeboat Free-Fall during Its Launching from Ship in Rough Seas

Abstract

In order to improve the accuracy of the freefall of lifeboat motion simulation in a ship life-saving simulation training system, a mathematical model using the strip theory and Kane’s method is established for the freefall of the lifeboat into the water from a ship. With the boat moving on a skid, the model of the ship’s maneuvering mathematical group (MMG) is used to model the motion of the ship in the waves. Based on the formula of elasticity and friction theory, the forces of the skid acting on the boat are calculated. When the boat enters the water, according to the analytical solution theory of slamming, the slamming force of water entry is solved. The simulation experiments are carried out by the established model. The results of the numerical simulation are compared with the calculation results of the hydrodynamics software Star CCM+ at water entry under initial condition A in the paper. The position and velocity of the center of gravity of the boat, the angle, and velocity and acceleration of pitch calculated by the two methods are in good agreement. There is a little difference between the values of translation acceleration calculated by the two methods, which is acceptable. This shows that our numerical algorithm has good accuracy. A qualitative analysis is performed to find the safe point of water entry under the condition of different wave heights and two situations of a ship encountering waves. Finally, the model is applied to the ship life-saving training system. The model can meet the system requirements and improve the accuracy of the simulation.

Research on an educational virtual training system for ship life‐saving appliances

“…The mathematical model incorporates motion models for ships, boats, rafts, flexible ropes, and other elements. For more detailed information on mathematical modeling, please refer to the research [38][39][40]. The key technologies for collaborative training in the system are discussed in Section 4, including network architecture, state synchronization, collaborative training modes, interaction management models, and evaluation models.…”

YOLOv3 Algorithm to Measure Free Fall Time and Gravity Acceleration

“…These measurements must provide accurate data to support a more reliable decision-making process. Some examples of industries that CSER use free fall calculations for decision-making regard rescue using lifeboats (Qiu et al, 2020), testing hydrodynamic performance (Liu et al, 2021), testing free-fall cone penetration test systems (Liu et al, 2021), analyzing orange fall motion in the food industry (Gharagani et al, 2018), and geotechnical investigations. Furthermore, using accurate measuring instruments to calculate the free fall motion is essential to achieve the best results.…”

Accuracy Analysis of the Measurement of Centre of Gravity and Moment of Inertia with a Swing

“…The position of the centre of gravity as well as the moment of inertia are essential input for the simulation of motions and forces of floating devices. CG is especially important for ships [17,18] and floating structures [19] including falling lifeboats [20] or floating wind turbines [21]. New and refitted ships are typically investigated with an inclination test [22,23] to ensure the precise location of the CG and that the desired stability is achieved.…”