The Tech

Ship Location

American Samoa

Acoustic Systems

Hull-mounted sonar system, pictured in drydock

Kongsberg EM302 Multibeam Echosounder

The EM302 is a hull-mounted 30 kHz multibeam echosounder composed of two long transducer arrays mounted in a T-shape on the hull of Nautilus. It was installed on the ship between 2012 and 2013 to collect bathymetric, backscatter, and water column data to identify areas or features of interest including gas seeps, create bathymetric maps for ROV dive planning and situational awareness. The EM302 can map the seafloor in water depths from 10 m to 7,000 m (33 ft to 22,965 ft) at ship speeds up to 12 knots.

  • Frequency 30 kHz
  • Depth Range 10–7,000 meters (33–22,966 feet)
  • Pulse Forms CW and FM chirp
  • Beamwidth 1° × 1°
  • Approximate swath width 3–5 times water depth, up to 8 km (5 miles)
  • Approximate grid resolution 10% water depth (e.g., 10 meters [33 feet] at 1,000 meters [3,281 feet] depth)

Knudsen Sub-bottom Profiler and Echosounder

The Knudsen 3260 is a sub-bottom echosounder mounted inside the hull of Nautilus. It operates at low frequencies (3.5–210 kHz) so that the sound it emits can penetrate layers of sediment to about 100 m below the surface. The sound that bounces back from each layer is captured by the system, creating a of cross section of the seafloor. Scientists can use the data to identify subsurface geological structures such as faults and ancient channels and levees. The Knudsen 3260 can operate in full ocean depths. The Knudsen system also collects 15 kHz single beam sonar data.

  • Profiler Knudsen 3260 Chirp sub-bottom profiler and echosounder
  • Operating Frequency Dual frequency, 3.5 kHz and 15 kHz
  • Power 4 kW on Channel 1 and up to 2 kW on Channel 2
  • Range 50 to 5,000 meters (164 to 16,404 feet)

Ultra-Short Baseline Navigation System

  • System TrackLink 5000MA system for USBL tracking of ROVs Hercules and Argus
  • Range Up to 5,000 meters (16,404 feet)
  • Positioning Accuracy 1° (~2% of slant range)
  • Operational Beamwidth 120°
  • Operating Frequency 14.2 to 19.8 kHz
  • Targets Tracked Hercules, Argus, and two additional transponders are available. With more transponders, up to eight targets including the ROVs can be tracked