Knowing the seabed topography is a prerequisite for safe navigation. Acquisition and collation of the bathymetry data form the basis of nautical chart production. Such data also facilitate other purposes such as port planning.

SURVEY VESSELS

The Hydrographic Office has three survey vessels. They are equipped with the latest multi-beam and single-beam echo sounders.
Differential Global Positioning System (DGPS) is being used as the primary means of position fixing for hydrographic surveys.

'Hydro 1' First Commissioned: Jan 2003 Length: 13.7m Breadth: 4.2m Draught (full load): 1.7m Cruising speed: 18 knots Crew: 3

'Hydro 2' First Commissioned: July 1998 Length: 18m Breadth: 8m Draught (full load): 2.5m Cruising speed: 12 knots Crew: 4

'Hydro 3' First Commissioned: December 1998 Length: 7m Breadth: 2m Draught (full load): 0.8m Cruising speed: 20 knots Crew: 2

EQUIPMENT

1) Multibeam Echo Sounder

a. Seabat 8101

b. Simrad EM3000D

2) Single Beam Echo Sounder

a. Odom Echotrac	b. Simrad EA502

3) TSS POS/MV 320

4) Sound Velocimeter

a. Valeport - CTD	b. Odom Digibar

5) Edgetech LS100 Side Scan Sonar

6)	RD Instruments Acoustic Doppler Current Profiler (ADCP)