• 수산해양기술연구
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• 제53권3호
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• pp.228-239
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• 2017

This study investigated the drag coefficient and lift coefficient of thirteen kinds of knotless nettings used for large purse seine gear. By comparing the hydrodynamic characteristics with nets of the previous study, the characteristics of this study were derived as a purse seine gear. Thirteen kinds of nettings with different length of bar (l) and diameter (d) were used in the experiment, out of which six kinds used the 30 mm in mesh size and three kinds with 40 mm. The drag coefficient ($C_d$) also increased with increasing d/l. It can be expressed as $C_d=3.71499(d/l)+0.76595$ at a current speed 0.4 m/s and $C_d=4.30324(d/l)+0.69056$ at a current speed 0.5 m/s. Compared with previous studies, drag coefficient values were similar to knotless net of similar d/l and smaller than drag coefficient of knot net. Therefore, using knotless net in a purse seine has the advantage of reducing the resistance acting on the purse seine gear.

• Fisheries and Aquatic Sciences
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• 제18권2호
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• pp.221-227
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• 2015

We analyzed the small-scale purse-seine gear that is used along the North Coast of Java, Indonesia, using computer-aided tools to modify the gear. Data from the middle position of the leadline showed that the maximum depth reached by the net was 30 m. A similar result was also calculated. According to the calculated result, the mean sinking speed of the current gear at the middle position of the leadline was 0.13 m/s, and the maximum tension during pursing was 1,794 kgf. The best sinking performance was found in modified gear that used a 30.3 mm mesh knotless polyester net. The maximum depth reached by the net was 38 m, and mean sinking speed was 0.16 m/s at the middle position of the leadline. The maximum tension during pursing was 1,044 kgf. Independent sample t-test results show that the mean sinking depth and sinking speed in the simulated and measured results did not differ (P > 0.05). These results are expected to improve the efficiency and selectivity of small-scale purse seine gear.