On improvement of "device for magnifying sounding width" and its application.
The author has previously studied and made a “Device for Magnifying Sounding Width”, with the intention of increasing efficiency in hydrographic surveying and security of safer navigation. Later, he improved the device by adding two accessories to it. One of them is a “Support" which enable easier installation of the device to surveying launch of any type, and the other is an “Inclination Modifying Device” which eliminates the inclination of the sonic wave transmitter. Although it is very important for the security of safe navigation,correct interpretation of abnormal or doubtful records appearing on echograms is very difficult. In order to complement the limited ability of the device in such a difficult area, the author developed a “ Sweeping Apparatus” which can be operated with a single surveying launch. The “Sweeping Apparatus” consists of a bottom wire, two depth wires, and a depth controlling rope. The bottom wire is hung from the arm of the “Device for Magnifying Sounding Width” by the depth wires. A weight is attached to each end of the bottom wire. Another smaller weight is fixed to its center. The depth controlling rope connects the smaller weight and the bows of the launch. Just below the sonic wave transmitter are set two reflectors to the bottom wire, which show the depth of the bottom wire in echograms. The bottom wire is dragged on the bottom or towed in settled depth. The length of the depth wires and the depth controlling rope are determined graphically as shown in Fig. 7. The Plates 7-11 show the records collected in the survey of Rumoi Ko in May 1968. In Plates 7, 8 it is clearly shown that the bottom wire collided with a projection of the bottom. Seven parallel courses were swept over the projection, and the shallowest depth was determined. Plates 12-16 show the records from the survey of Muroran Ko in May 1968. By the sweeping at the place in Plate 16, sea weeds were lifted up, and the projection proved to be a remainder of dredging.
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| Format: | Journal Contribution biblioteca |
| Language: | Japanese |
| Published: |
1971
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| Online Access: | http://hdl.handle.net/1834/16345 |
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