GPSMAP 640 Owner’s Manual 37
Marine Mode: Advanced Conguration
Turn the following alarms on or off:
Marine
Tornado
Severe Storm
Flood
Flash Flood
My Boat
From the Home screen, touch Congure > My Boat.
Keel Offset
—offset the surface reading for the depth of a keel,
making it possible to measure depth from the bottom of the keel
instead of from the transducer location. Enter a positive number to
offset for a keel. Enter a negative number to compensate for a large
vessel that may draw several feet of water.
To adjust the Keel Offset:
1. From the Home screen, touch > My Boat > Keel
Offset.
2. Use the on-screen keyboard to specify the offset.
If you are measuring down to the keel (transducer installed
at the water line), enter a (+) positive number.
If you are measuring up to the water line (transducer
installed on the keel), enter a (-) negative number.
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3. Touch Done to accept the number.
Turn Transition Distance—set how far before a turn in a route
that you transition to the next leg.
Other Vessels
From the Home screen, touch Congure > Other Vessels.
NOTE:
To congure AIS or DSC information for other boats, your
unit must be connected to an external AIS or DSC device.
AIS
—turn AIS on or off. AIS alerts you to area trafc by providing
the boat IDs, the position, the course, and the speed for boats that
are within range and equipped with a transponder.
DSC—turn DSC on or off.
AIS Alarm (AIS only)
—set an alarm to sound when other AIS-
equipped vessels are within a specied range. This is used for
collision avoidance and can be customized.
Range—change the measured radius of the Safe Zone ring to a
specied distance from 500 ft. to 2.0 nm (or 150 m to 3 km, or
500 ft. to 2.0 mi.).
Time to (Safe Zone)
—sounds an alarm if AIS determines that
a target will intersect the Safe Zone within the dened time
interval (ranging from 1 to 24 minutes).
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