Depth Alarm; Fish Id Alarm; Low Battery Alarm - Humminbird 748 3D Operation Manual

Depth Alarm sounds when the depth becomes equal to or less than the menu
setting.
Fish ID Alarm sounds when the Fishing System detects fish that correspond to
the alarm setting. Fish ID Alarm will only sound if Fish ID+™ is on. For example,
if you've set the Fish ID Alarm to sound for Large fish only, the Fish ID alarm
will sound when a large-sized fish is detected.
Low Battery Alarm sounds when the input battery voltage is equal to or less
than the menu setting. The battery alarm will only sound for the battery that is
connected to the Fishing System. The Low Battery Alarm should be set to warn
you when the battery voltage drops below the safety margin that you have
determined.

Depth Alarm

Settings: Off, 1 to 100 ft, or 0.5 to 30 m [International
Models only], Default = Off

Fish ID Alarm

Settings: Off, All, Large/Medium, Large, Default = Off
Off
All
Large/Medium
Large

Low Battery Alarm

Settings: Off, 8.5V - 13.5V, Default = Off
45 Alarms Menu Tab