Marport Canada Inc has announced its new trawl geometry system. TrueTrawl™ is a wireless monitoring system designed to improve trawl geometry in pelagic and bottom trawling operations.
Precise control of trawl gear is beneficial for both economic and environmental reasons. Efficient trawling necessitates that the spread between the trawl doors is consistent and that trawl height remains stable, reducing skewing of the gear. When trawl doors are square to the net, the water forces inside the trawl are equally distributed and the trawl fishes most efficiently. A fully optimised trawl should be symmetric with correct geometry.
However, the one critical element that is usually unknown to the fisherman is trawl geometry. The operator does not always know whether the trawl is off to one side, and therefore may be skewed, or is negatively affected by underwater currents and tides.
Marport's new TrueTrawl system clearly displays when the trawl doors are properly aligned and the trawl is working at maximum efficiency. This helps operators to keep the trawl properly aligned even when fishing in difficult conditions such as slopes or strong tides.
The TrueTrawl system consists of a master geometry transponder placed on the headrope with slave geometry sensors placed on each trawl door, the clump, the wings or other locations as desired by the operator. Each sensor communicates with another using reliable underwater wireless acoustic communications technology developed by Marport. The TrueTrawl system is unique in that each trawl door sensor is multi-functional. In addition to measuring geometry, each door sensor can measure other critical data required for efficient operation of the trawl, including distance between the doors, door depth, door angle (pitch and roll) and water temperature around the door.
The TrueTrawl software uses real time 3D graphics to display trawl geometry from a number of different viewing perspectives. When the tension on either side of the trawl exceeds that of the other side due to factors such as increased drag, currents, sediments, or steep slopes, it is instantly displayed on the computer monitor. In addition, trawl door angle and height relation to each other is displayed.
The company says that the TrueTrawl system is expected to provide higher accuracy than “symmetry” sensors.
Marport is now booking orders for production units with first deliveries scheduled for September 2008.
Marport will be exhibiting the TrueTrawl system at Icefish 2008.
