| 摘要 |
PURPOSE:To confirm the state of reaching of the long body to the bottom even though visual observation is difficult due to rapid water stream, by detecting the sound generated by the contact of a rigid body and other bodies around the rigid body. CONSTITUTION:Rope 4, which tows the rigid body 3, moves the rigid body 3 along the long body 1. Projections 5 are provided on at least the bottom surface of the rigid body 3 and generate sound when they are contacted with the sea bottom 8. Irregular parts 6 are provided in an insertion hole of the rigid body 3 for the long body 3. When the sound of the contact of the rigid body and the base rock at the sea bottom and the like is generated, the long body is positioned at the sea bottom. When the contact sound of the rigid body and the sea bottom is not generated even though sliding sound is generated from the rigid body and the long body, the long body is floating in the sea. When the sliding sound of the rigid body and the long body and the contact sound with the sea bottom are not generated, the rope, which tows the rigid body, is slackened. |
