You should also note that it is possible to have the sensitivity set too high such that reflection off of suspended matter or air bubbles will begin to black out the display.
In the manual mode the depth scale does not change automatically and the digital bottom depth is not displayed. To once again activate the automatic mode, depress the Sensitivity Auto "On/Off" switch.
5.Audible Alarms: The LCR 3004 is equipped with two audible alarms, a Fish Alarm and a Bottom Alarm.
Fish Alarm:
The LCR Fish Alarm will give a short alarm sound anytime a return is detected between the boat and the bottom. It will not alarm on the bottom but only on objects off the bottom.
To activate the Fish Alarm press the Fish Alarm "On/Off" button. The indicator "F" in the upper left of the screen will indicate that the Fish Alarm is on. The Fish Alarm is operational only while the LCR is in the automatic mode. See "Manual Mode" in this section for use of the alarm in the manual mode.
The Fish Alarm may occasionally sound when no target is displayed. This can happen when a target is detected close to the bottom but is too close to be seen on the display. It can also happen when the display sweep speed is slow such that the target was detected but is gone by the time the display is updated.
To turn the Fish Alarm off, simply press the Fish Alarm "On/Off" button again. Bottom
Alarm
The Bottom Alarm is activated by pushing the alarm "On/Off" button. When first activated, the alarm is set at five feet. The desired alarm depth can be adjusted up or down by pressing the depth set button and the increase * or decrease = button. When the increase or decrease button is pressed once, the alarm setting will change one division. If the button is held down the setting will move as long as the button is held down. The alarm setting is indicated down the right side of the display. The Bottom Alarm may be set anywhere from 4 feet to the maximum depth. When the bottom enters the alarm range it will trigger a continuous audible signal.
The Bottom Alarm will operate both in the automatic and manual modes, however, the operation is slightly different depending on what mode is on.
Automatic Mode: In the automatic mode a continuous alarm will sound only when the bottom depth is equal to or less than the alarm setting. Fish entering the alarm range will not trigger the alarm, unless of course the fish alarm is on.
Manual Mode: In the Manual Mode either the bottom or fish can trigger the alarm. If the bottom depth becomes equal to or less than the alarm setting, a continuous alarm will sound. If a fish enters the alarm range a short, quick alarm will sound. Since the fish alarm is active only in the automatic mode, positioning the bottom alarm range close to the bottom will allow you to have a fish alarm in the manual mode.
The alarm depth will adjust itself when the depth range changes from one range to another. Thus a depth alarm set at ten feet while on the 30 foot depth range will remain at ten feet deep should the unit advance to any other range. To set the alarm with the most accuracy, set it using the lowest depth range.