Latest Notices to Mariners (NTM)
Date: 2017-12-15
Issue No.: 25

Latest Notices to Mariners (eNTM of HKENC)
Date: 2017-12-08
Issue No.: 25_2017

Home > Useful Information > Hydrographic Surveying

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.

Hydrographic Surveying

'Hydro 1'

Hydro 1

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

'MD205'

MD205

First Commissioned: June 2015
Length: 17m
Breadth: 4.5m
Draught (full load): 1.5m
Cruising speed: 12 knots
Crew: 4

'Hydro 3'

Hydro 3

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

1) Single-head Multi-beam Echo Sounder on ‘Hydro 1’

Specification
  • Operating frequency : 240kHz
  • Number of beams : 101
  • Beam width : 1.5°
Single-head Multi-beam Echo Sounder on ‘Hydro 1’  Single-head Multi-beam Echo Sounder on ‘Hydro 1’

2) Dual-head Multi-beam Echo Sounder on ‘MD205’

Specification
  • Operating frequency : 300kHz
  • Number of beams : 254 (single-head) or 508 (dual-head)
  • Beam width : 1.5°
Dual-head Multi-beam Echo Sounder on ‘MD205’  Dual-head Multi-beam Echo Sounder on ‘MD205’

3) Single-beam Echo Sounder on survey vessels

- is a simple and reliable electronic sounding device engaged in close shore sounding surveys

Single-beam Echo Sounder on survey vessels  Single-beam Echo Sounder on survey vessels

4) Motion Sensor

- is a high-tech electronic sensor used to determine the effects of vessel movement such as ‘roll’, ‘pitch’ and ‘heave’ during field operation for data post-processing

Motion Sensor  Motion Sensor  Motion Sensor

5) Sound Velocimeter

- is a useful tool in hydrography to provide sound velocity at different water depths so that the deviation of transmitted sounding beams due to variation of sound velocity in water, can be compensated during data post-processing

Sound Velocimeter  Sound Velocimeter