In spread measurements, two sensors always work in pairs. One is used as a “spread” sensor, while the other is a “remote”. Depending on sensor type, both these sensors may also provide additional measurements.
Use a “spread” sensor on the port door and a “remote” sensor on the starboard door. Both sensors are normally mounted in special adapters, but you may also attached them to the wing-end or warp using snap hooks or rope.
The “spread” sensor communicates with the “remote” sensor using a special transverse communication link. By means of this link it measures the exact distance between the two sensors. The information is transmitted to the vessel by the “spread” sensor.
Why is this important?
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 this measurement to be one of the most important to obtain efficient trawling.