## 3 Models and Assessment Methods
### Assessment Methods
#### 3.2.3 Assessment of Three Vessels  
The safety assessment of the motion exhibited by the three vessels is considerably intricate. Fluctuations in the motion responses of the two lifting barges and the shipwck exhibit distinct characteristics. Therefore, when evaluating the motion response of the three vessels, it is crucial to consider not only the MA of the 6 DOFs but also the RMS and CV. In other words, a relatively stable movement pattern can prevent damage to the shipwck's structure, thereby reducing the operational challenges faced by the two lifting barges and enhancing the safety of the salvage operation. This manuscript adopts two evaluation modes to assess the motion responses of the three vessels. The first mode involves scoring under the same working condition but in different stages, while the second mode involves scoring between other working conditions. Once the scoring under the first mode is completed, the second scoring mode can be initiated. Section 5.2.1 contains some examples of the assessment of the three vessels. * Mode 1: Assessment among different stages (intragroup scoring). The assessment of Mode 1 involves three stages of salvaging a shipwck: P1, P2, and P3. P1, P2, and P3 collectively represent the entirety of the shipwck salvage process. By closely examining dynamic responses during these three phases, it becomes possible to ascertain the safety of the salvage operation. In the numerical simulation, P2 corresponds to most of the salvage duration and constitutes the most critical stage in the entire operation. Suppose the 6 DOFs exhibited by the two lifting barges and shipw demonstrate better stability during the P2 stage than during the P1 and P3 stages. In that case, the safety and stability of the entire salvage operation are maximized. Specific evaluation rules are outlined in Table 3. The higher the score, the less safe it is to perform salvage operations. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Category** & **Elements** & **Rule** & **Score** & **Remark** \\ \hline \multirow{8}{*}{Safety} & & Both assessment elements in P2 are lower & & \\  & & than the average of the corresponding & 1 & Safe \\  & & assessment elements in P1 and P3, & & \\ \cline{1-1}  & & One of the assessment elements in P2 & & \\ \cline{1-1}  & & exceeds the average of the corresponding & & \\ \cline{1-1}  & & assessment elements in P1 and P3, but it is & 2 & Medium \\ \cline{1-1}  & & not the maximum value among P1, P2, & & \\ \cline{1-1}  & & and P3. & & \\ \cline{1-1}  & & One of the assessment elements in P2 & & \\ \cline{1-1}  & & represents the maximum value among & & \\ \cline{1-1}  & & corresponding assessment elements in P1, & & \\ \cline{1-1}  & & P2, and P3. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Assessment Rules for Mode 1. * Mode 2: Assessment among different working conditions (intergroup scoring). Mode 1 describes scoring between stages (P1, P2, and P3) under the same working condition. As salvage operations involve numerous working conditions, Mode 2 encompasses scoring between different working conditions. In the numerical simulation presented in this manuscript, there are three vessels, denoted by letters \"a\", \"b\", and \"c\", as illustrated in Figure 1b. Following the evaluation method of Mode 1, each vessel can calculate two scores: the safety score (SA) and the stability score (ST). SA and ST scores are 1, 2, or 3. Consequently, there are six possible scores: \(SA_{a}\), \(SA_{b}\), \(SA_{c}\), \(ST_{a}\), \(ST_{b}\), and \(ST_{c}\). Considering the maximum MA and RMS of the three vessels during the P1, P2, and P3 stages as the evaluation elements, six new samples emerge: \(MA_{a}\), \(MA_{b}\), \(MA_{c}\), \(RMS_{a}\), \(RMS_{b}\), and \(RMS_{c}\). These samples are then ranked based on their magnitude, and the ranking score is recorded as \(RAN_{i}\), where \(i\) ranges from 1 to 6. A higher ranking corresponds to a better score. For instance, Chapter 4.2 entails five waves emanating from different directions.