• Ships
• Multibeam Bathymetry
• Side-Scan Sonar
• Sub-bottom Profile
• Remotely Operated Vehicle (ROV)
• Cores

R/V MacGinitie

CCGS R.B. Young

CCGC Otter Bay

CCGS Vector

Multibeam Bathymetry

In the San Juan Islands and Boundary Pass region, multibeam bathymetric sonars are used to map both the shallow and deep-water areas as well as to determine morphologic and geologic features on the seafloor. Multibeam bathymetry acquires depth information which determines the time it takes for an acoustic pulse to travel through the water column, reflect off the seafloor, and return to receive aperture (McQuillin and Ardus, 1977; Masson, 2003).

A multibeam bathymetric system is equipped with a multi-element transducer with many (30 - 150) individual soundings of both the water depth and the echo strength for each ping. A wide swath (about five to seven times the water depth), ensonifies the seafloor and creates the mapping system’s footprint. The footprint increases with the distance between the transducer array and the seafloor. Automatic seafloor tracking programs within a multibeam bathymetric system can perform a variety of tasks, including determining depths and echo strengths, correcting for transducer motion, and calculating a geographic coordinate for every individual sounding. Survey lines are spaced apart which allow for overlapping coverage of the seafloor.

Systems used:

Reason SeaBat 8101 (240 kHz)

Simrad EM 1002 (95 kHz)

Simrad EM 3000 (300 kHz)

Reson SeaBat 8101 Multibeam Echosounder

Simrad EM 1002 Multibeam Echosounder

Simrad EM 3000 Multibeam Echosounder

Deep Ocean Engineering Phantom ROV

Side-Scan Sonar

System used:

Simrad MS 992 (120/330 kHz)

Side-scan sonar data, like backscatter data, provide information about seafloor composition, and roughness and sediment properties. These data are acquired by towing a sub-surface unit, or towfish, from the stern of a vessel. Sound is emitted from the transducer in fan-shaped beams, which hit the seafloor and return to the receiver where the intensity of the signal is measured and recorded.

Sub-bottom Profiler

System used:

Huntec Deep-Tow (DTS)

Seistec

Sub-bottom profiles are obtained by emitting large pulses of sound which penetrate the seafloor. Sedimentary layers, for example, can be identified beneath the seafloor using seismic profiling.

Remotely Operated Vehicle (ROV)

System used:

Deep Ocean Engineering Phantom ROV

A Remotely Operated Vehicle (ROV) has the capability to perform a variety of underwater tasks, including the acquisition of video imagery, still photos, sediment cores, and rock and other seafloor samples. ROVs provide necessary groundtruthing information that accompanies other data (such as multibeam bathymetry or side-scan sonar data) collected in a particular study area. Groundtruthing is necessary when creating marine benthic habitat maps as the groundtruthed data provide detailed observations of the imaged features and associated biota.

Cores

System used:

Benthos Piston corer (20')

Extracting sediment from beneath the seafloor is a method of groundtruthing a desired study area. Sediment core information is essential to marine benthic habitat studies as it may provide necessary information regarding sediment transport, surface area of sediment, size, shape and arrangement of grains, and permeability.