Kongsberg EM 302 Multibeam Echosounder
EV Nautilus recently installed a new hull-mounted Multibeam echosounder for efficiently mapping the seafloor. The EM 302 is a 30 kHz multibeam echosounder composed of two long transducer arrays mounted in a T-shape on the hull of EV Nautilus. The ship is now capable of mapping the seafloor from 10 to 7000 meters (33 – 22,965 feet) water depth as the ship cruises at 8-10 knots.
The multibeam echosounder collects bathymetric, surface sediment characteristic, and water column data. The information it collects is useful for identifying areas or features of interest; creating bathymetric charts for ROV dive planning and situational awareness; and locating hydrothermal vents and gas or oil seeps.
Bathymetric data from the EM 302 during its trial run in Toulon Canyon, France.
Knudsen K3260 Sub-bottom Profiler
The K3260 is a sub-bottom echosounder mounted inside the hull of EV Nautilus. The echosounder operates at low frequencies (3.5-210 kHz) allowing sound to penetrate the layers of sediment. This creates a cross-section of the seafloor, revealing the structure of the sub-surface geology. Scientists can use the data to identify ancient features including channels, faults, and levees. The K3260 can operate in full ocean depths.
EM 302 Sea Acceptance Trial in Toulon Canyon, France in Spring 2013
Shipwreck imaged with the EM 302 near France
E/V Nautilus also carries two shipboard side-scan sonar towfish systems named Diana and Echo.
Diana is an Edgetech 4200 HF side-scan sonar towfish that uses dual frequencies with a range of approximately 200 meters on either side. The Diana system is capable of being towed to a depth of 2000 meters, but is currently limited by cable length to a working depth of 600 meters. Diana’s transducers can also be installed on the Argus towsled, which increases the towing depth to a maximum of 4000 meters. Diana is used to create accurate, high-resolution maps of the seafloor and to identify targets of interest that ROVs Hercules and Argus may explore in more detail. The primary advantage of this system is the quality of data that is produced.
Towfish Diana Specifications
Depth Rating 2,000 meters (currently limited to 600 meters by cable length)
Sonar Edgetech 4200 sidescan sonar (300/500 kHz)
Echo is a five-channel Benthos deep-tow side-scan sonar system rated to 3,000 meters water depth. Echo’s operating frequencies are 100 and 400 kHz, which cover a total swath width up to 1,000 meters. Echo is also equipped with a Chirp 2-7 kHz subbottom profiler that permits identification of subseafloor features. Towfish Echo, like Diana, is used to create accurate, high-resolution maps of the seafloor and to identify targets of interest that ROVs Hercules and Argus may explore in more detail.
Towfish Echo Specifications
Depth Rating 3,000 meters
Sonar Benthos SIS-1500 sidescan sonar (100/400 kHz)
Subbottom sonar (3-7 kHz)
Sensors Falmouth Scientific CTD