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底层拖网有时需要根据鱼群的垂直移动调节进行离底作业。笔者提出,在不改变现有网具的情况下,主要通过调节沉浮比、拖速等因素,单船拖网以网板接触海底,双船拖网以部分夹棕曳纲接触海底,使网具贴伏或升离海底的方法。通过实物测试,空间力学模拟和水槽模型试验,对底层拖网兼作离底拖曳的可能性进行了基础的实验研究。单船拖网通过调节沉浮比(0.5～0.9)和拖速(2.0～3.5kts),拖网的离底高度可在1～27m 范围内变动。双船拖网当沉浮比为0.55～0.86,拖速为2.1～3.5kts 时,拖网的最大离底高度可达11.93m。
Bottom trawl sometimes need to be adjusted according to the vertical movement of fish to the bottom operation. The author suggests that without changing the existing network of tools, mainly by adjusting the sinking ratio, dragging and other factors, single-board trawl to the bottom of the screen contact with the sea, double-board trawl to some of the folder to contact the sea, V or lift off the bottom of the sea. Through the physical test, space mechanics simulation and sink model test, the basic experimental research on the possibility of the bottom trawl also acting as the bottom dragging is carried out. Single boat trawl through the regulation of sinking ratio (0.5 ~ 0.9) and towing speed (2.0 ~ 3.5kts), bottom of the trawl can be within the range of 1 ~ 27m range. When the sinking ratio is 0.55 ~ 0.86 and the towing speed is 2.1 ~ 3.5kts, the maximum height of the trawl can reach 11.93m.