Netmind System

Sensors

Headline Height Sensor

Headline Height Sensor measures the distance from the headline to the footrope and from the footrope to the bottom.
The sensor is equally effective on bottom and mid-water trawls, since it detects both the footrope and the bottom, when
the bottom is within range. In addition to providing the trawl's opening height, this sensor gives a reading of the amount of
the fish in the mouth of the net on a scale of 1 to 10.

Measurement: Distance from headline to bottom
Distance from headline to footrope
Relative fish density in net opening.

Measurement range: 60m (200 ft)

Accuracy: ±1% of full scale.

Measurement Frequency: 200 kHz

Weight in air: 9 Kg
Weight in water: 4.3 Kg

Door Spread Sensors

Door Spread Sensors are considered to be the most important sensors on the net. They ensure the doors are in alignment and
that the correct sweep angle is achieved. Manipulation of the doors is used to increase or decrease the headline, in turn improving
catching efficiency. Properly aligned doors means the trawl is more hydrodynamic, thereby reducing fuel consumption and towing
duration. Using door spread sensors will clearly show if the doors have crossed over while shooting, if they've collapsed during a
tow, or if the net is skewed or dragging on the bottom. Towing with improperly positioned doors can cause undue stress and
damage to the entire trawl system.

Measurement: Distance between master and slave sensor.
Measurement range: 300m (1000 ft)
Accuracy: ± 1% of full scale.
Measurement Frequency: 90 kHz
Weight in air: Master, 9 Kg; Slave, 7 Kg
Weight in water: Master, 4.3 Kg; Slave, 3.5 Kg

Wing Spread Sensors

Wing Spread Sensors operate in the same way as door spread, but are mounted on the wings of the trawl to provide yet more
valuable information.

Measurement: Distance between master and slave sensor.
Measurement range: 150m (500 ft)
Accuracy: ± 1% of full scale
Measurement Frequency: 150 kHz
Weight in air: Master, 9 Kg (19 lbs.); Slave, 7 Kg (15 lbs.)
Weight in water: Master, 4.3 Kg; Slave, 3.5 Kg

Depth Sensor

The Depth Sensor measures the depth of the trawl. This sensor is essential for mid-water trawling. Skippers can: Watch the
trawl descend and know when to start towing. Monitor the trawl's depth as they fish along changing bottom depths and edges.
The Depth Senor helps control the depth of the trawl to match the location of the fish.

Measurement: Depth (pressure).
Measurement Range: 5 to 1400 M (766 fathoms)
Accuracy: ±1% of full scale.
Weight in air: 7 Kg
Weight in water: 3.5 Kg

Temperature Sensor

The Temperature Sensor measures the water temperature at the mouth of the trawl. Knowing the water temperature can be
important information since many species prefer a narrower range of temperatures. A great deal of time can be wasted towing
in water that is the wrong temperature.

Temperature Sensor:
Measurement: Water Temperature
Measurement Range: -2°C to +30°C
Accuracy: ±0.1°C
Weight in air: 7 Kg
Weight in air: 3.5 Kg

Catch Sensor

The Catch Sensor is used to let the Skipper know when to pull the net. When the cod end of the net expands, due to the weight
of the fish, the catch sensor is activated and a red light comes on in the cod end of the trawl in the graphics screen. By allowing the
net to be pulled as soon as the cod end is full, the catch sensor can reduce wasted time towing with a full net, and can eliminate the
problems associated with overfilling the net. You can use up to 3 catch sensors on a trawl.

Measurement: Net expansion (indicates when net is full).
Weight in air: 10 Kg
Weight in water: 4.7 Kg

Grid Sensor

This sensor is mounted on the trawl grid using a stainless steel mounting bracket and monitors the grid angle, thus allowing the
skipper to make the necessary adjustments to his trawl in order to correct and maintain the optimum fishing angle. The Grid Sensor
can perform angle measurements from 3? to 93? with an accuracy of ? 1?. The sensor is powered by a rechargeable NiCad battery
which has an operating life of 200 hours between charges.

Measurement: Tilt
Measurement Range: 3° to 93°
Accuracy: ±1°
Weight in air: 7 Kg
Weight in water: 3.5 Kg

Bottom Contact Sensor

The latest addition to the NETMIND? suite of wireless sensors, is suspended vertically from the footrope of the trawl. When
the trawl is off the bottom, gravity will cause the sensor to hang close to the vertical position, thus the bottom contact sensor
will indicate that the trawl is not on the bottom. When the trawl is on the bottom, the sensor will be in a horizontal position
on the bottom and will indicate that the trawl has touchdown.

Measurement: Angle
Telemetry Range of 2 Kilometers
Update rate between 7 and 9 seconds
Accuracy: +/-1 degree
Weight in air: 7 Kg
Weight in water: 3.5 Kg

Battery Charger
Power requirements: 110-230VAC, 47-63 Hz
Number of Units charging: 1
Charging time: 2 Hours

Created on 01/26/2004 11:26 AM by admin
Updated on 07/20/2006 11:13 AM by admin