Notus Electronics Ltd has developed a new Trawl Door Height Sensor, in response to the increase in the use of semi pelagic doors for bottom trawls.
These doors typically fly just off the ocean floor while the trawl remains on the bottom, so the company sys that the height from the door to the ocean’s bottom is crucial to the proper operation of the door.
Notus’ Trawl Door Height Sensor is a single sensor that can provide trawl door height, door spread, trawl warp length and door angle. This information is calculated using a sounder inside the sensor that detects height off the ocean floor.
Optimal performance of these doors is achieved when the doors are equal height from the ocean floor, and flying the doors too high may bring the trawl off bottom. Gear damage and reduced fishing may result from the doors impacting the bottom. To ensure proper orientation and accurate height readings, door angle is also measured.
This sensor also monitors other critical pieces of information like door spread and trawl warp length. Door spread is calculated by installing a slave on the opposite door. Trawl warp length is measured to an accuracy of better than 0.5m.
This new sensor was recently successfully tested on the FV Frank Maiken out of Skagen Denmark. Twin trawl gear was used while flying the doors.
The Trawl Door Height Sensor can be added to most Notus Trawlmaster systems by simply updating the software and adding the sensor(s).
