フライラインの力学

－フォルスキャストの検討－

抄録

Lure fishing and fly-fishing have been positioned as sports deliberately different from the traditional Japanese fishing-style. In the case of fly-fishing, casting is the element which anglers must master in order to cast a fly, done so by using the weight of a line. This study uses experimental and computational analysis to investigate the dynamic behavior of a fly line. Fly-fishing is constituted by various elements, but the importance that casting holds is extremely large. Fling speed, the casting process and the loop shape of the line while in flight are important for the proper presentation of flies. Moreover, the shape of a fly line is also important for a long cast or controlled cast. Therefore, the most suitable casting method will be clarified from the viewpoint of sports engineering and human dynamics. Anglers usually do “False cast” in the actual fishing field in order to put a fly for long distance and in order to control the line orbit. This technique increases the line speed and the kinematical energy. “False cast” consists of forward cast and back cast. Anglers wait until the line becomes straight forward after the cast, then they start the next cast. Anglers usually change the line orbit while they do “False cast”. Therefore, the line flies appropriate distance. In this paper, a rod, a line and arms are modeled by using rigid bodies and links. The time history behavior of the model is calculated by pseudo angler velocity of the arms. The difference of the line behavior with respect to the time interval between forward cast and back cast is evaluated. It is clarified that there is an appropriate interval.