# Impact Force Mechanism of a Trimaran Model and Its Experimental Validation
## 5 Water-Slamming Experiment and Force Analysis
### Slamming Experiment When the Trimaran Entered the Water
#### 5.2.2 Experiment in the Case of Flexible Cladding with a 1 mm Thick Silica Gel Plate  
The test data and the calculated slamming-pressure coefficients for each working condition are listed in Table 3.  
For the relationships of speed and pressure versus time, we chose height H16 as an example. The characteristic curves of speed and pressure versus time are shown in Figure 13.  
As observed from Figure 13, the trimaran model slowed down gradually, especially after the slamming pressure reached the peak. At 4.18 s, the model entered the water and began to slow down. And at around 4.245 s, the connection bridge hit the water.  
The data from falling experiment are shown in Figure 14 for six different heights (H11-H16).  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Working** & & & & & & & & & \\
**Condition** & & & & & & & & & \\
**Pressure/Pa** & **Speed** & **Pressure/Pa** & **Speed** & **m/s** & **Speed** & **Pressure/Pa** & **Speed** & **Slamming-Pressure** \\
**Coefficient** & & & & & & & & & \\
**Cofficial** & & & & & & & & & \\ \hline P01 & 1915.4 & 1.640 & 1.42 & 1607.1 & 1.668 & 1.16 & 1590.7 & 1.781 & 1.00 \\ \hline P02 & 646.0 & 1.640 & 0.48 & 1248.9 & 1.668 & 0.90 & 1116.4 & 1.781 & 0.70 \\ \hline P03 & 1289.0 & 1.556 & 1.06 & 1833.4 & 1.668 & 1.32 & 2452.3 & 1.741 & 1.62 \\ \hline P04 & 1957.8 & 1.556 & 1.62 & 2407.9 & 1.668 & 1.73 & 3010.5 & 1.741 & 1.99 \\ \hline P05 & 2608.8 & 1.556 & 2.16 & 2891.3 & 1.634 & 2.17 & 3439.9 & 1.741 & 2.27 \\ \hline P06 & 2019.2 & 1.556 & 1.67 & 1914.7 & 1.634 & 1.43 & 2959.1 & 1.741 & 1.95 \\ \hline P07 & 2114.5 & 1.640 & 1.57 & 1665.3 & 1.725 & 1.12 & 1690.2 & 1.781 & 1.07 \\ \hline P08 & 1853.1 & 1.640 & 1.38 & 1262.4 & 1.725 & 0.85 & 1473.1 & 1.781 & 0.93 \\ \hline P10 & 1915.4 & 1.640 & 1.42 & 1607.1 & 1.668 & 1.16 & 1590.7 & 1.781 & 1.00 \\ \hline  & & & & & & & & & \\
**H14** & & & & & & & & & \\ \hline P01 & 1886.5 & 1.925 & 1.02 & 2313.2 & 2.049 & 1.10 & 1923.5 & 2.091 & 0.88 \\ \hline P02 & 1089.0 & 1.925 & 0.59 & 1907.9 & 2.049 & 0.91 & 1606.1 & 2.091 & 0.73 \\ \hline P03 & 2115.6 & 1.925 & 1.14 & 2460.8 & 2.049 & 1.17 & 1989.5 & 2.054 & 0.94 \\ \hline P04 & 2578.8 & 1.925 & 1.39 & 3117.4 & 2.049 & 1.49 & 2616.9 & 2.091 & 1.20 \\ \hline P05 & 3532.2 & 1.925 & 1.91 & 2891.3 & 2.049 & 1.38 & 3385.6 & 2.091 & 1.55 \\ \hline P06 & 6669.4 & 2.136 & 2.92 & 2358.0 & 2.049 & 1.12 & 2874.2 & 2.091 & 1.31 \\ \hline P07 & 2127.2 & 2.030 & 1.03 & 2684.6 & 2.183 & 1.13 & 2693.5 & 2.184 & 1.13 \\ \hline P08 & 1682.5 & 2.030 & 0.82 & 4946.5 & 2.105 & 2.23 & 2409.6 & 2.184 & 1.01 \\ \hline P10 & 1886.5 & 1.925 & 1.02 & 2313.2 & 2.049 & 1.10 & 1923.5 & 2.091 & 0.88 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Experiment with 1 mm silica gel sheet.  
As observed in Figure 14, with an increase in drop height, the coefficient of the slamming pressure drops. Furthermore, as shown in Figure 14 the coefficient is a little greater than 1 in most cases. This is because the silica gel plate turns part of the water pressure into air pressure.