# Numerical Simulation of Seakeeping Performance on the Preliminary Design of a Semi-Planing Craft
## 3 Data Analysis
### Full-Scale Experiments
#### 3.2.3 High Sailing Speed (U = 33 Knots, \(H_{1/3}\) = 1.3 m, \(\overline{T}\) = 4.2 s):  
Figure 5a presents the comparison of results for the simulation and on-board measurement (in terms of heaving motion) for all wave angles at high sailing speed. The simulation results were sufficiently consistent with the experimental results, except for wave angles of 0\({}^{\circ}\)-60\({}^{\circ}\), and the heaving motion was underestimated. In terms of rolling motion (Figure 5b), the simulation results were consistent with the experimental results, except for the wave angles of 0\({}^{\circ}\)-30\({}^{\circ}\) for which the rolling motion was underestimated. Regarding pitching motion (Figure 5c), the simulation results were sufficiently consistent with the experimental results.  
Figure 2: Complete schematic diagram of the series 62 craft.  
Table 2 presents a comparison between the simulation results and the on-board measurements for heaving, rolling, and pitching motion at different sailing speeds in sea state 3. The results indicated that at low and medium sailing speeds, the estimated motion values at some wave heading angles were slight overestimations compared with the experimental results; moreover, at a high sailing speed, the estimated heaving and rolling motions were slightly underestimated compared with the experimental results. The differences between the sea trials and simulation data were mainly caused by southwesterly surges (long waves) in the local summer season. Although there existed some discrepancies due to prediction limitation in the low-frequency region, it was demonstrated that the simulation results agreed reasonably with the on-board measurements.  
Figure 3: Comparison of results for the simulation and on-board measurement in terms of (**a**) heaving, (**b**) rolling, and (**c**) pitching motion at low sailing speed.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Knots** & **Motion** & \(\mathbf{0^{\circ}\text{--}60^{\circ}}\) & \(\mathbf{60^{\circ}\text{--}120^{\circ}}\) & \(\mathbf{120^{\circ}\text{--}180^{\circ}}\) \\ \hline \multirow{3}{*}{7} & Heave (m) & \(-0.15\) & \(-0.07\) & \(-0.03\) \\ \cline{2-5}  & Roll (\({}^{\circ}\)) & \(-0.78\) & \(3.1\) & \(3.37\) \\ \cline{2-5}  & Pitch (\({}^{\circ}\)) & \(1.43\) & \(1.32\) & \(1.53\) \\ \hline \multirow{3}{*}{14} & Heave (m) & \(-0.11\) & \(0.02\) & \(0.08\) \\ \cline{2-5}  & Roll (\({}^{\circ}\)) & \(-1.31\) & \(2.34\) & \(2.93\) \\ \cline{2-5}  & Pitch (\({}^{\circ}\)) & \(1.82\) & \(1.49\) & \(1.48\) \\ \hline \multirow{3}{*}{33} & Heave (m) & \(-0.34\) & \(0.02\) & \(-0.05\) \\ \cline{2-5}  & Roll (\({}^{\circ}\)) & \(-3.37\) & \(-1.95\) & \(-2.21\) \\ \cline{2-5}  & Pitch (\({}^{\circ}\)) & \(0.46\) & \(0.46\) & \(-0.34\) \\ \hline \end{tabular}
\end{table}
Table 2: Mean deviations of the simulation data (in terms of heaving, rolling, and pitching motion) for all wave heading angles.  
Figure 4: Comparison of results for the simulation and the on-board measurement in terms of (**a**) heaving, (**b**) rolling, and (**c**) pitching motion at medium sailing speed.