Simrad PX Sensor Measurements
Recommended For:
- Commercial Fishing
- Coastal Fishing
In spread measurements, two sensors always work in pairs. One is used as a 'spread' sensor, while the other is a 'remote. Depending on the sensor type, bit 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 attach them to the wind-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.
Correct door spread is important in to obtain the correct sweep angle, as this ensures optimal trawl performance. Door behaviour and stability during shooting and towing are many also monitored by these sensors. This measurement is regarded by many as the most important to achieve efficient trawling.
If you use bottom, pelagic, or twin trawl the geometry measurements will:
To maximise the performance and catch efficiency, the trawl and the warps must be adjusted properly. This is essential to ensure a square trawl and minimum skew. Any disturbance to the trawl movements may have a negative impact on the catch. This is particularly important on a bottom trawl, A skewed bottom trawl will result in unstable bottom contact, and create escape routes for fish below the gear and through the side panels. On pelagic and danish seines a skewed net will make the gear unstable, and the catch reduced.
Optimal trawl geometry is therefore vital for maintaining the catch efficiency.
The Simrad geometry measurements are based on the fact that a correct rigged trawl and danish seine has exactly the same distance measured from the centre of the headrope or footrope to either door or trawl wing. These distances must be identical independent of weather conditions, sea state, or water currents.
Example:
On the left trawl, distance 'A' on the port side is longer than distance 'B' on the starboard side. The trawl is unbalanced.
On the right trawl, distances 'A' and 'B' are identical, and the trawl is symmetric for maximum efficiency.
Measuring only the door spread 'C' will not detect a distorted geometry.
Geometry measurements can be made in two ways:
Using differential geometry allows you to save the sensor battery, or you can add a second measurement to the sensor. However, differential geometry contains less information than the standard geometry measurement since the two lengths are not submitted.
Fishing in too warm or too cold water may just be a waste of time and money. The same applied to a pelagic trawl on the wrong side of a thermal layer. Using advanced technology the sensor tells you the exact sea water temperature while you are fishing.
The water temperature is an important parameter. Fish and Bait are temperature sensitive and normally found within specific temperature zones for feeding and spawning.
For any kind of trawling, you can use this sensor to monitor and log the temperature. Thereby increasing your knowledge about the correlation between temperature, fish concentration and catch efficiency. On a purse seine net by monitoring the temperature you can see when you pass through a thermo-cline.
The sensor measures the height over the bottom. That is the distance from the bottom up to where the sensor is physically located. This measurement provides you with a valuable range of applications for bottom and pelagic trawling.
Place the height sensor behind the headrope, and it will tell you the height of the trawl opening. This allows you to adjust your equipment immediately if the opening is reduced, and you will avoid losing catch.
With a height sensor behind the footrope, you will know at once if the trawl sinks closer to the bottom. If you used a second sensor behind the headrope, the difference between the two height measurements will give you the vertical height of the trawl opening.
Depth measurements provide you with accurate information about the current depth of the sensor. If you for example place the sensor behind the headrope, you will be able to monitor the depth of the headrope. The functionality provided but the Simrad catch monitoring system will also allow you to monitor the depth changes so that you can make the relevant adjustments whenever necessary.
On a bottom trawl, you can use the sensor to achieve full control when shooting and to position the trawl on the slope.
During pelagic trawling, you know how important it is to position the trawl relative to the largest concentration of fish. By using a depth sensor you can monitor the exact depth of the gear relative to the surface, and adjust the trawl depth accordingly. Additional depth sensors on the doors can be used to monitor if the doors stay at the same depth.
If battery status is important to you, you can use one of the measurements available to report the current status. This information is displayed using the TV80 software.
