Furuno CI-68 Operator's Manual page 37

BOTTOM SEARCH
BOTTOM SEARCH enables reacquisition of temporarily lost ground echo, in the water
tracking mode. When the bottom echo is lost for a short while due to air bubbles, or the
equipment tends to track on false bottom, acquire the bottom echo manually as follows:
1. Set BOTTOM SEARCH to YES and close the menu. The rectangle cursor appears on
the display.
2. Press any function key. The tide vector display appears along with the echo level
display.
3. Use ▲ or ▼ to set the cursor on the bottom echo.
4. Press the [MENU] key to finish and close the menu.
BTM TIDE TRACK
Choose how to track bottom tide, in the ground tracking mode.
ON: Measuring depth of layer 3 changes automatically with the bottom depth to track on
near-bottom tide. In this case the layer 3 indications shows "BTTM" instead of the tide
measurement depth.
OFF: Normal selection of measuring depth for layer 3.
ALM/KEY BEEP
A key beeps to confirm correct key input, input error or error message. You may turn this
beep on or off as desired. The beep sounds when an alarm setting is violated regardless of
whether this item is turned on or off.
WT SPD DEPTH
Set the reference depth at which to measure ship's speed in the water tracking mode. Set
the depth for which you want to know the water tracking speed in reference to a specific
depth. The setting range is 2-400 (m).
RESET TRIP LOG
Set the trip distance to zero (0). Choose YES and then you are prompted " PRESS ANY
FUNCTION KEY TO EXECUTE." Press any function key to reset the trip log to zero.
TEST
Choose the diagnostic test to execute: General (program no. display, memory check, etc.),
panel or pattern. For further details, see paragraph 4.4.
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How to acquire bottom echo
3. CUSTOMZING THE SYSTEM
3-5