Business guide

　Main purpose of the submarine cable route survey is to select the most suitable cable laying route. This survey starts from the collection of data 　

　on natural condition and human work condition to select the survey route. Field work is consisting of the land site survey, inshore survey by

　small boat and offshore survey by large vessel, and the survey flows as the data acquisition of geophysical survey and magnetic survey, data

　analysis, selection of field recommended route, sampling and other necessary survey.

●DTS（Desk Top Study）

　DTS is the study to select the suitable survey route and to obtain the necessary data for cable construction. Collection data consist of natural 　

　condition such as bathy, geology, oceanography and meteorology, and human work condition such as fishing activity, shipping activity, military 　

　activity, existing cables, etc. These data are analyzed to select the survey route, and the field survey starts.

●Land Site Survey

　Landing point and others are determined by S-GPS or VRS-GPS, and the topography around landing site is measured by K-GPS, total station, 　

　level, etc.

●Diver Survey

　Topography at coastal area is measured by diver cross section leveling. Diver survey along the route is carried out for the photography of video 　

　and camera, clarification of seabed material and sediment thickness and existing cable search by magnetometer.

●Offshore Survey

　Generally, the inshore survey by small boat and the offshore survey by large vessel are carried out in parallel. The survey contents are as 　

　follows:

• Bathymetric survey by multi-beam echo sounder
• Seabed feature survey (Side scanning) by side scan sonar
• Geological survey by sub-bottom profiler
• Seabed sampling by gravity corer and grab sampler

　Others such as current survey and magnetic survey are performed as necessary.

●Data Analysis

　Acquisition data are analyzed on board day by day to supply the chart such as bathymetric chart, seabed feature chart and geological chart for 　

　the selection of most suitable route and daily meeting.

　Search for underwater missing article can be done efficiently and economically by using the side scan sonar and/or multi-beam echo sounder. 　

　These technologies are mainly utilized for the search of the crashed plane, wreck and underwater ruins with our rich experiences.

　Gravity piston corer is used for the undisturbed sampling as possible. Core tube can be chosen the length from 2m to 12m for the purpose such

　as the survey of cable, submarine construction, resources and academy by using medium to large vessel or crane barge.