Bathymetry mapping for pioneer ship voyages using side scan sonar in Sembulang Waters, Riau Islands

Abstract

The SSS C-MAX CM2 Tow fish instrument is an acoustic instrument that operates at a frequency of 325 kHz with a maximum sounding distance of 200 m towing cable length of 50 m, producing images and textures within a large area. This study aimed to process data from the SSS C-max CM2 measurement survey to obtain MSL and LLWL tidal corrected bathymetry data, which is used to create a sailing map for pioneer ships in Sembulang Waters, Riau Islands. The SSS data acquisition was carried out on March 15 - 18, 2021, in Sembulang Waters using a 5GT vessel with a Batam State Polytechnic team. Tidal data was taken using a tidal board placed at Sembulang Pier. SSS data processing used Sonar Wiz 7 licensed software obtained from Pushidrosal with the application of several geometric and radiometric corrections. Geometric corrections included layback, bottom tracking, and slant range correction. Radiometric correction consists of Beam angle Correction (BAC), Automatic Gain Control (AGC), Time-Varying Gain (TVG), and Empirical Gain Normalization (EGN). Tidal data was processed using the Admiralty method. SSS data was exported into .csv format for making topographic maps of the seabed based on the depth and width of the ideal shipping lane based on the specifications of traditional fishing vessels used at the research site. The actual depth value of the Sembulang Waters ranges from 0.5 meters to 27.7 meters. The depth of the waters towards the east is getting deeper. The depth value of the Sembulang Waters in LLWL conditions ranges from 0 meters to 26.5086 meters, shows that several locations need to be avoided for ships sailing area and need to be dredging for the safety of ships ≥ 5GT.