Lowrance HOOK-4x Operation Manual page 24

A: Keel offset (e.g. -1 foot)
If, for example, the distance is 1 foot, it will be
input as (minus) –1 foot.
Water speed calibration
Calibrates a paddlewheel speed sensor.
Temperature calibration
Calibrates data from the transducer temperature
sensor with data from a known temperature source
to ensure the accuracy of temperature information.
Sonar operation | HOOK X series
Reset water distance
Reset Water Distance to zero.
Transducer type
Transducer
Selects the type of transducer model attached to
your unit.
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