Global co-operation for Bangladesh trawl fleet sonar installation

Kongsberg Maritime engineers from Kuala Lumpur, Busan and Horten, together with an engineer from local distributor SRL Cosmos Trawl have joined forces to complete an extensive sonar and instrument installation on the pelagic trawl fleet of the Karnaphuli River in Chittagong, Bangladesh.

The project took place during October and November 2016, and included installation of eight SX93 low frequency fish finding sonars. The system is part of the SX90 family of long range, high resolution, low frequency fish finding omni sonars, used for searching and catching schooling fish as well as scattered fish in up to 8000m in any direction from the vessel.

Five FS70 third wire trawl sonars, which monitor the trawl opening of a pelagic trawl, were also installed. Communication is through a cable between the trawl and the vessel. The sonar unit is placed on the top of the opening of a mid water trawl, and will show the opening itself as well as fish entering. When the trawl is filled with the required amount of fish, catch sensors placed on the cod end (very aft end) of the trawl will provide an alarm through an acoustic link.

Several vessels in the fleet also had ES70 echo sounders and Simrad TV80 wireless trawl instruments installed. The ES70 is a fish finding echo sounder with up to 6 simultaneous frequencies, capable of finding single fish down to 1200m. Using split beam transducers, it will show fish size distribution, helping the user determine the fish species.

The Simrad TV80 Catch Monitoring system is wireless and can be used with a variety of acoustic sensors. All these sensors can be placed on a trawl or purse seine to simultaneously monitor key parameters. Typical parameters are depth of net or trawl, net or trawl door height over seabed, roll/pitch angle of trawl door, distance between trawl doors, and fish filling of trawl.

After finalising the above installations, sea trials and operator training was performed during ordinary fishing in the Bay of Bengal.