Kongsberg Simrad TV80, Справочное руководство

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Depth measurement
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.
By having a sensor measuring depth, you can monitor the exact depth of the gear relative
to the surface, and adjust the trawl depth accordingly. During seining, with the depth
measurement you can monitor the depth of the net, and the descending speed of the
net. When the sensor is mounted on a Danish Seine, the depth measurement helps you
monitor the sinking speed of the net, and it will tell you when to start hauling once the
net has stopped sinking.
Flow measurement
In catch monitoring terminology, the flow measurement presents the speed of the water
current entering the trawl opening.
Different species swim at different speeds. When you know the water speed (flow) in
the trawl’s opening or the funnel in real time, you can increase or decrease the vessel
speed to adjust to the target species.
Geometry measurement
When using bottom and pelagic trawl – or twin trawl - the geometry measurement is
vital to measure if the trawl is skewed. Then, you can correct the geometry by adjusting
the warp lengths
With a danish seine, the geometry measurements will allow you to detect variations
in the distance from the centre of the headrope to either wing. You can also detect
differences in the rope lengths when the seine is closed (distances between the wings
should then be close to zero).
Height measurement
Height is the distance from the bottom and up to wherever the sensor is physically
located.
• Place the sensor behind the headrope to know the Height and Geometry measurements.
• With a sensor behind the footrope you will know at once if the trawl sinks closer
to the bottom.
• With a sensor mounted vertically on the footrope of a purse seine, you will know the
remaining distance (height) from the bottom.
Opening measurement
The opening of a trawl is the vertical distance from the headrope to the footrope.
Overview of catch monitoring measurements