< Topic >It is difficult to receive the resistance of the water, the plumb bob for fishing which the ultra wave reflects efficiently is offered.SolutionsInside is filled up, with the restoration component whose such as oil acoustic impedance is close to the water or jieru 3 the stream-line outer hull globose was formed with metal such as lead and tungsten inside 1 which was formed with the rubber or resin and outer hull 1 or consists metal component 2 of the polyhedron. Because of this, it sinks to underwater at brief, at the same time is likely to appear in the fish school detection machine.< Choice figure >Drawing 1【課題】水の抵抗を受け難く、超音波が効率良く反射する釣り用錘を提供する。【解決手段】内部がオイル又はジェル等、音響インピーダンスが水に近い充填部材3で満たされ、ゴム又は樹脂で形成された流線形の外殻1と、外殻1の内部に鉛やタングステン等の金属で形成された球形又は多面体の金属部材2で構成されている。これにより、短時間で水中に沈み、且つ魚群探知機に映り易くなる。【選択図】図1
