Document Title - Geoscience Australia

Lord Howe High Resolution Grids
Appendix 1
MULTIBEAM SYSTEMS
The swath data were acquired by four research vessels (Table 9): IFREMER’s L’Atalante, CSIRO’s
Southern Surveyor, Lamont-Doherty’s Maurice Ewing and NIWA’s Tangaroa.
These vessels have bathymetry multibeam acquisition systems designed for different depth ranges.
The Southern Surveyor and Tangaroa operate in the mid-depths (1000-2500 m), whilst the
L’Atalante and Ewing systems are more suitable for deep water operations (> 3000 m). Most of the
multibeam swath data collected in the shallow depths were acquired by the Southern Surveyor on
voyage GA-2461 (SS06/2008).
The table below summarises the different acquisition systems, operating frequencies, number of
beams and depth range for each vessel.
Table 9: Multibeam systems
ECHO SOUNDER EM12D EM300 ATLAS HYROSWEEP
DS
Builder Kongsberg Simrad Kongsberg Simrad Atlas Hydrographic
Vessel L’Atalante Southern Surveyor/ Maurice Ewing
Tangaroa
Antenna Flat (V shape) Flat horizontal ?
Depth range (m) 50 – 12000 20 – 4000 3000 – 11000
Depth category Very deep Moderate Very Deep
Frequencies (kHz) 13 32 15.5
No. of beams/ping 162 135 59
Angular aperture 150º 150º 90°
Width of beams
emitting X receiving
1.8°x3.5° 1°x1° 2°x2°
Figure 32 shows the relationship between swath width and water depth for the EM300 and EM12D
systems illustrates the mapping potential of 13 kHz systems in deeper water. The 32 kHz EM300
system reaches its optimal mapping capacity in about 2500 m water depth, which limits it to the
upper portions of the Lord Howe Island volcano.
The EM300 however has narrower beamwidths, higher sonar frequency and a close beam spacing
than the other systems which makes it more useful for higher resolution investigations in shallower
areas (< 1000 m).
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