Furuno GP-3500 - Manual (Page 112)

8. ALARMS
8-8
8.9 Bottom Alarm
Note: This alarm requires depth data.
The bottom alarm sounds when the bottom echo is within the alarm range set.
To activate the bottom alarm the depth must be displayed.
1. Press the [MENU] key to show the main menu.
2. Press the [6] key to show the ALARMS SETUP menu.
3. Rotate the [ENTER] knob to select BOTTOM ALARM.
4. Press the [1] key to select “1. ON.”
5. Rotate the [ENTER] knob to select DEPTH.
6. Press numeric keys to enter the starting point of the alarm range.
7. Rotate the [ENTER] knob to select RANGE.
8. Press numeric key to set the alarm range, and then press the [ENTER] knob.
9. Press the [MENU] key several times to close the menu.
Note: To deactivate the alarm, select “2. OFF” at step 4.