## 4 Numerical Modelling and Validation
### Basin Test and Validation  
A numerical-simulation-based scale experiment was conducted on the vessel, with the scale dimensions set at 70. The wave tank, which is the primary facility for conducting experiments on oceanic structures, was utilized. Within the wave tank, the target object typically assumed the shape of a scaled-down model. Spherical structures were used for wave generation, and the wave tank itself measured 50 m in length, 30 m in width, and had a depth of 4 m. [PERSON]'s similarity theory was applied to craft the ship model. The lifting barges had dimensions of 2 \(\times\) 0.8 \(\times\) 0.19 m, with a draft of 0.123 m. The shipw had dimensions of 3 \(\times\) 0.33 \(\times\) 0.3 m. The experimental arrangement and equipment are depicted in Figure 4.  
Figure 4 displays various components: Figure 4a showcases the wave-making pool. Two symmetrically arranged spherical structures create waves. Upon rotation of the eccentric wheel, the stay ropes connected to the base of the spherical structures extended and contracted, causing vertical movement and creating waves. The termination point of the pool was equipped with a wave-absorbing structure, allowing for a realistic simulation of sea waves. Figure 4b portrays the salvage scene of a shipw. In Figure 4c, a capsized Wigley boat represented the shipw, featuring pallets on its underside. Thirty-four lifting rings were affixed to the pallet, with thirty connected to the barge via cables and four linked to a circle of steel pipes. The steel pipe was connected to a hook. Thirty lifting cables connected the shipw and barge as the hook gradually descended. Custom-made lifting cables were employed, consisting of lightweight cables and custom springs, meeting the gravitational similarity and elastic similarity criteria. The formula used to calculate the tension deformation of the lifting cables [36] was as follows:  
\[T_{m}=\frac{C_{p}d_{p}^{2}(\Delta S/S)^{n}}{\lambda^{3}} \tag{13}\] \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & **Cells** & \multirow{2}{*}{**Roll (Deg)**} & \multirow{2}{*}{**L1 (F/10\({}^{6}\) N)**} & \multirow{2}{*}{**L5 (F/10\({}^{6}\) N)**} & \multirow{2}{*}{**L7 (F/10\({}^{6}\) N)**} \\  & **(Millions)** & & & & \\ \hline Coarse & 27 & 1.846 & 6.442 & 5.218 & 5.046 \\ Medium & 33 & 1.894 & 6.277 & 5.110 & 4.969 \\ Fine & 39 & 1.929 & 6.129 & 5.024 & 4.901 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Analysis of three grids. Figure 4: Experimental layout and equipment: **(a)** Wave-making pool; **(b)** The salvage scene of a shipw; **(c)** Shipwreck; **(d)** The equipment used to adjust the center of gravity and moment of inertia; **(e)** Lifting barge; **(f)** Tension sensor; **(g)** The instrument for measuring the ship’s attitude. where \(T_{m}\) denotes the tension of the model, \(C_{p}\) represents the modulus of elasticity, \(\Delta S/S\) corresponds to the relative elongation, and \(n\) assumes a value of 1.5. Figure 4d showcases the equipment used to adjust the center of gravity and moment of inertia. Figure 4e depicts the lifting barge, which possesses fifteen connecting rings linked to the shipw via pulleys and cables. Additionally, Figure 4f showcases a sensor employed for tension measurement. By dividing the lifting cables into two segments and attaching the sensor to both ends, the force exerted during the lifting of the shipw can be measured. Lastly, Figure 4g portrays an instrument for measuring the ship's attitude, placed within the barge's cabin, to enable the determination of 6 DOFs. Figure 5 portrays the Response Amplitude Operator (RAO). Considering the limited space of the manuscript, the MA of the 6 DOFs is demonstrated for the lifting barge during stages P1, P2, and P3 under wave action in 90\({}^{\circ}\) and 180\({}^{\circ}\) directions. The RAO in this illustration is defined as the ratio of the MA of the 6 DOFS [34] to the wave height.