Simrad PI Twin Spread Summary
Check the doors on a twin trawl!
Used on bottom and pelagic twin trawls the Twin Spread and Remote sensors provide crucial information about your trawl behaviour. The three sensors working together tell you the exact distance between the two trawl doors.
Information from the sensor
The PI Twin Spread will always communicate with two PI Remote sensors. Together they monitor the physical distances between the two pairs of trawl doors during bottom and pelagic trawling.
Use a Spread sensor on the port door and Remote sensors on the centre clump and on the starboard door. All the sensors are normally mounted in special adapters, but you may also attach them to the wing-end or warp using snap hooks or rope.
The Spread sensor communicates with the two Remote sensors using two special transverse communication links. By means of these links it measures the excact distance (maximum 350 meters) between the sensors. The information is is transmitted to the vessel by the Twin Spread sensor, and the PI system calculates the distances between the doors.
As you already know, correct door spread is important in order to obtain the correct sweep-angle, as this ensures optimal trawl performance. Door behavior and stability during shooting and towing is also monitored by these sensors. Many regard these sensors among the most important sensors to obtain efficient trawling.