## 2 Numerical Model  
### Configuration of Stow Net  
Figure 1 shows 2D and 3D views of the stow-net model. Material properties and design parameters of the stow net are summarized in Table 1. The stow-net model is selected from one of the actual designs used in southwest coast of South Korea. The stow net consists of a net assembly, a location buoy, a rope, and mooring lines. The net assembly is made up of a net, a head rope, a ground rope, buoys, and weights in detail. The height and width of the net entrance and length of the net assembly are 15 m, 30 m, and 60 m, respectively. The net is made of polyethylene, and small weights are installed between threads to adjust the buoyancy to weight ratio (BWR) of the net to 1.01. Head and ground ropes, which are made of oak, are installed on top and bottom of the net entrance. One of the most important parameters to determine net-stretching performance is the BWR of the net entrance, and in this study, the BWR of the net entrance is fixed to be 1.5. Buoys are placed at both ends of the head rope to create additional buoyancy while weights are located at both ends of the ground rope to adjust the BWR of the net entrance. Polypropylene is used for mooring lines and the rope. Especially, a SPM is used for the station keeping purpose with heavy anchor at a target location. In this case, the end point of SPM is assumed to be fixed. A rope is used to connect the location buoy and the net assembly. The location buoy is installed to show the location of the stow net visually. Moreover, the primary goal of this research is to develop monitoring system for the stow net to extensively, continuously monitor essential parameters in real time so that fishers can estimate net functionality through entrance area and monitor whether fishing gear is lost. Monitoring sensors are positioned at the mooring line #1 to measure tension and location buoy to measure translational motion and rope tension. Measured data will be wirelessly transferred to a fishing boat. With the pre-assessed data base, for instance, by reading the mean mooring tension and surge mean offset of location buoy, current velocity can roughly be predicted. Then, using the relation between net entrance area and current velocity (e.g., Figure 6), the functionality of the net can indirectly be assessed. Sudden decrease of mooring or rope tension close to zero means that they are disconnected.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Item**} & \multicolumn{1}{c}{**Value (Type)**} & \multicolumn{1}{c}{**Unit**} \\ \hline \multirow{4}{*}{Net} & Stretching Length & 60 & m \\  & Width & 30 & m \\  & Height & 15 & m \\  & Material & Polyethylene & - \\  & Density & 970 & kg/m\({}^{3}\) \\ \hline \multirow{4}{*}{Head and ground ropes} & Length & 30 & m \\  & Diameter & 0.1 & m \\  & Material & Oak & - \\  & Density & 750 & kg/m\({}^{3}\) \\ \hline Weight located to ground & Mass & 150 & kg \\ rope & Number & 2 & - \\ \hline Buoy located to head & Volume & 0.243 & m\({}^{3}\) \\ rope & Number & 2 & - \\ \hline Buoyancy to weight ratio & Net entrance & 1.5 & - \\ (BWR) & Net & 1.01 & - \\ \hline \multirow{4}{*}{Mooring line and rope} & Diameter & 9, 14, 34 & mm \\  & Material & Polypropylene & - \\  & Density & 910 & kg/m\({}^{3}\) \\ \hline \multirow{4}{*}{Location buoy} & Material & Styrofoam & - \\  & Density & 50 & kg/m\({}^{3}\) \\ \cline{1-1}  & Volume & 0.2 & m\({}^{3}\) \\ \cline{1-1}  & Diameter & 0.73 & m \\ \hline \hline \end{tabular}
\end{table}
Table 1: Material properties and design parameters.  
Figure 1: 3D (**a**) and 2D (**b**) views of the stow net and description of all analyzed parameters.