Operation Manual

References
221
850-165186 / Rev.B
Trawl calculator
These settings are used to set up the PI54 parameters related to
the Trawl calculator.
To access the parameters, press the ADJ button when you have
a graphic display in the active window. Then, press the GAIN+
button four times until the settings appear. You can also press
the MENU button to access the Echo quick menu, select
Graphic setup (8), and then press the GAIN+ button four
times.
Purpose
The Trawl calculator is used when you have chosen to
superimpose sensor data onto t he Graphic display. However, in
order to position the sensor marker correctly on the echogram,
you need to calculate the delay. This is because the echo sounder
information is provided by a transducer located under the vessel,
while the sensors are located on the gear, which may be
positioned several hundred meters behind the vessel. To adjust
for this delay, you must calculate the value (in minutes) based
on the vessel’s speed, the wire length and the depth of the gear.
You can do it manually and enter a Marker line delay in the
Marker line setup dialogue, or you can leave the calculation to
the Trawl calculator.
For a complete procedure, refer to the Operational procedures
chapter.
Parameters
Trawl calculat or mode: Select Auto or Manual. When
Selecting Auto allows you to retrieve or enter trawl data, and
the PI54 will perform the calculation. Selecting Manual
switches the Trawl calculator off.
Towing speed: Select Manual to enter the average vessel speed,
or Auto to allow the PI54 to retrieve the information
automatically. If you select Auto you can choose to read the
speed over ground (SPG) or the speed through water (STW).