# Application of Collision Warning Algorithm Alarm in Fishing Vessel's Waterway
## 4 Application in Fishing Vessel's Waterway Based on Vpass Data
### Case Study of the Collision Warning Algorithm Application Based on Vpass Data  
1. Case 1  
In Case 1, six ships encountered each other where ships A, B, and C sailed northeast, ship D sailed southwest, ship E drifted at a low speed through the water, and ship F sailed southwest at a low speed while changing its course toward the northeast. The 10 min ship navigation data were extracted and the analysis results are shown in Figure 8 and Table 5.  
Figure 7: (a) Vpass data plot for 7 days and (b) the plot after the interpolation of Vpass data with 10 s intervals for 7 days. Figure 8a shows the tracks of the six ships with different colors representing the alarm stages and Figure 8b shows the time-zone comparison in the graph of the alarms generated on ship D for DCPA and TCPA criteria, PARK model risk value criterion, and developed algorithm. Table 5 shows the results of the data analysis on the alarm situations at ship D.  
According to Figure 8a and Table 5, ship D encountered ship C head-on at 9.7 s, which generated the first main alarm. As the distance between the ships decreased, the alarm stage changed to the second main alarm, and the alarms were continuously generated. At 113.2 s, the alarm was turned off as the risky situation for ship C had terminated. Later from 247.8 to 317.2 s, the encounter with ship B caused the continuous generation of the second main alarm for ~69 s. As shown in Figure 8b, when only DCPA and TCPA criteria were applied, the first main alarm was generated momentarily and then was terminated. However, when the developed algorithm was used, the alarms were generated continuously until the first main alarm changed to the second main alarm. Furthermore, when only DCPA and TCPA criteria were applied, the alarms were terminated at 76.1 s despite the very close encounter between the two ships. In the case of the developed algorithm, the alarms were generated until the risky situation had terminated completely when the distance was 76.88 m. However, when the PARK model risk value criterion was applied, the pre-alarm, first main alarm, and second main alarm were turned off alternately and repeatedly, which would confuse ship operators. 2. Case 2  
Figure 8: (**a**) Diagrammatic representation of the track of the alarms generated from the results of case 1 and (**b**) graphical representation of the alarms generated on ship D based on the time (from the top, alarms based only on DCPA and TCPA criteria, alarms based only on PARK model risk value criterion, and alarms based on the algorithm). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Time (s)** & **Target Ship** & **Distance (m)** & **DCPA (m)** & **TCPA (s)** & **Risk** & **Alarm** \\ \hline
9.7 & Ship C & 1067.53 & 29.59 & 149.97 & 7.0 & first Main \\
41.3 & Ship C & 815.54 & 34.83 & 83.39 & 7.0 & second Main \\
113.2 & Ship C & 76.88 & 76.88 & 0.04 & 6.0 & second Main \\
247.8 & Ship B & 753.38 & 30.41 & 70.35 & 7.0 & second Main \\
317.2 & Ship B & 8.20 & 8.12 & 0.11 & 7.0 & second Main \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Analysis of the situation of alarm generation on ship D in case 1. Case 2 presents a situation in which four ships encountered one another. Ships A, B, and C sailed northeast toward Jindu Harbor, while ship D drifted around Jindu Harbor. The 10 min ship navigation data were extracted, and the results of the analysis are shown in Figure 9 and Table 6.  
According to Figure 9a and Table 6, ship B approached Jindu Harbor at a steady speed and encountered ship D, which drifted around Jindu Harbor, creating a risky situation. Thus, the first main alarm was generated at 171.6 s, and it changed to the second main alarm after 1.3 s. The alarm was generated continuously until 226.8 s when the PARK model risk value decreased below five and the alarm was turned off.