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491 Echo Sounder Operations Manual Page 7
Powering the 491 on and off
As part of its power-up sequence, the navigator automatically
activates the 491.
The 491 is automatically shut off by the navigator when you
press and hold
PWR
until the screen goes dark.
Setting up the 491
Your 491 should be installed by a qualified marine technician.
Your satisfaction with the system’s performance will be greatly
influenced by the practical knowledge and experience of the
installer. Unlike GPS or other marine electronics systems, echo
sounder installation is as much an art as a science.
The installation procedure includes setting up the following
options:
• the transducer’s depth
• the speed and temperature
• the calibration for the speed sensor
• the calibration for the temperature sensor
• the gain calibration for the transducer
You may wish to change the following options from time to
time to match your personal preferences:
• depth units (feet, meters, or fathoms) on the screen
• temperature units (Celsius or Fahrenheit) on the screen
• temperature scale (lowest and highest) on the screen
• (961/962 only) automatic saving of *FISH##* or
*THERM##* waypoints when the 491 detects the presence
of fish or a certain water temperature that you’ve set
Using 491 with the
961/962
Before starting, you should double-check that the 961/962’s
Port 3 is set to the 490 option:
1. Press STAR until you reach the SERVICE MENU screen.
2. Press PORT SETUP.
3. Press PORT 3.