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Towed gear tracking

Olex connects to several underwater acoustic instrumentation systems to track the position of towed gear in 2D and 3D. The behaviour of gear under water becomes easier to read.

Vessel and trawl position in 2D view The vessel and trawl position in 2D

Vessel and trawl position over the seabed in 3D view The vessel and trawl position over the seabed in 3D

3D view with the trawl door tracks in 2D 3D view with door tracks in 2D

3D view with Simrad ITI and ES60 systems 3D view with Simrad ITI and ES60 systems

USBL underwater positioning displayed in 2D and 3D USBL underwater positioning in 2D and 3D

Trawl tracking with Simrad ITI

  • Once the ITI system is connected to Olex, the trawl is shown on screen.
  • If the ITI has a depth sensor, the trawl depth is recorded and its height above the seabed can be seen in 3D.

SINTEF, the Norwegian foundation for scientific and industrial research, has also built trawling and ferry manoeuvring simulators on the Olex interface.

Trawl tracking with iXTrawl Geonet

Developed by Thomson Marconi Sonar from the Pacha 2000 system, the Geonet trawl instrumentation system was then developed and sold by iXTrawl (formerly Acelma), in Pont-l’Abbé, France.

Designed for small-scale fishing (Geonet 700) as well as industrial fishing (Geonet 2000), Geonet is a cable-free trawl geometry and acoustic positioning system that aims to optimise catches while reducing the risk of snagging. It is made up of rugged acoustic beacons. The standard installation has two positioning beacons, on the doors, and an acoustic antenna under the vessel. Geonet gives the distance of each beacon from the vessel, the position, spread and offset of the doors, and the water depth and temperature at the beacons.

With Geonet connected to Olex, the skipper can display and record in 2D and 3D the position and track of the doors relative to the vessel.

Positioning of ROVs and towed fish

  • Same functions with the Simrad HPR 300P and HPR 4xx (HPR 400, for example) and ORE Trackpoint II systems.
  • All the information about underwater gear is recorded: their movement can be followed and their track kept.
  • Olex can track several objects at once.

Examples:

  • ACES: a study by a Swedish marine biology laboratory of a coral environment 300 m deep off Norway, using a ROV fitted with an HPR 410P USBL (Ultra Short Baseline) acoustic system;
  • Tjärnö marine biology laboratory: marine habitat mapping with ROV video;
  • Oceana, an ocean conservation organisation.

Updated : October 2026