The Department is constantly engaged in surveys of water depths and land features, in order to provide mariners with up-to-date nautical charts and other publications reflecting the manmade changes such as construction and development of harbor facilities and natural changes.

Control Surveys

Triangulation and traversing are carried out at harbors and coastal areas to obtain accurate positions of control points, which are used for building a framework of the nautical chart, as well as to fix positions of aids to navigation such as lighthouses, buoys, traffic signals, chimneys, etc.which are necessary for hydrographic surveying and ships, navigation. Recently GPS receivers are mainly used in control surveys.

Bathymetric Surveys

Knowledge of the depth of water is one of the most crucial elements for the safety of ships, navigation. Therefore, precision echo sounders are used to measure the depth of water in the harbor and along the shipping route. At the same time, the position of the survey ship is continuously fixed by a GPS. Until recently four-beam echo sounders have been the only tool for investigation of the seabed. Recently, smaller size multibeam echo sounders are introduced, which are small enough to equip on a smaller survey ship to carry out a precise investigation of the seabed, especially sandwave areas, sunken ships, etc. The Department is carefully examining whether it can be fully satisfy the requirement to be used for the hydrographic surveying. The multibeam echo sounder continuously acquires sounding data of high resolution and high accuracy from maximum 150 degree swath. The enormous sounding data is connected with positioning data from GPS, and automatically processed into bathymetric charts and whale's-eye-view maps.

Multibeam Echo Sounder for Shallow Waters

Record of Sandwave obtained by Multibeam Echo Sounder for Shallow Waters