Tilt variation and wake turbulence in the otter board of a bottom trawl during fishing operations

서지정보

ㆍ발행기관 : 한국수산해양기술학회(구 한국어업기술학회) ㆍ수록지정보 : 수산해양기술연구 / 53권 / 4호
ㆍ저자명 : Yong-Hae KIM

목차

Introduction
Materials and Methods
Results
Discussion
Conclusion
Acknowledgements
References

영어 초록

The tension of warp from trawler and sea-floor contact can generate tilt and wake turbulence around otter boards. Preliminary measurements of otter board tilt and 3-D flow velocity during bottom trawl operations were taken using a vector instrument to investigate the effects of wake turbulence at the trailing edge of the otter board. Tilt data (i.e., yaw, pitch, and roll) at 1 Hz and flow data (velocities in the towing, lateral, and vertical directions) at 16 Hz were analyzed to determine their periods and amplitudes using global wavelet and peak event analyses. The mean period (±standard deviation) of the tilt from the peak event analysis (5±2 s) was longer or double than that of flow velocity (3±2 s). The two periods also had a significant linear relationship. The turbulence rate of flow was 30-50% at the trailing edge and was closely related to roll deviation. The frequency of phase difference ratios (i.e., peak time differences between tilts and flow periods) was significantly different from random occurrence in two trials, possibly due to side tidal effects. However, in the other trials, flow peaks were random, as shown by the even peak times between tilts and flows. Future studies should focus on reducing tilt variation, wake turbulence, and bottom contact to stabilize otter board motion.

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