NorthStar 490 Echosounder Operation Manual page 63

Setting the bottom
490 Echo Sounder Operations Manual Rev. B2
To set the bottom alarm:
1. At the ECHO screen, press MORE .
2. Press ALARM .
3. At the ALARM screen, press BOTTOM ALARM .
The options on the BOTTOM ALARM window are on/off
and the depth setting.
You can set the depth level for the seabed, so that as soon as
the bottom is shallower than this depth, the bottom alarm will
level
sound.
To set the bottom level, at the BOTTOM ALARM window, press
the CURSOR PAD up or down to set the depth, or use the
KEYPAD to manually enter the desired depth.
The 490's depth indicator reflects the depth below your vessel's
transducer, not below the keel. Ask your installer for the exact dis-
tance between your transducer and your keel. This value must then
always be manually added to the 490's depth indicator, or else
entered into the transducer's depth setting on the
SOUNDER SETUP
Chapter 7 - Setting the Alarms
Bottom alarm window
NOTE:
screen for an automatically correct reading.
ECHO
Page 7-5