Depth Offset; Speed Calibrate; Temperature Calibrate; Sonar History - Raymarine L1250DRC Owner's Handbook Manual

Chapter 4: System Setup

Depth Offset

The depth offset is added to the measured depth value before it is displayed.
You can specify the depth as a positive value (Waterline Offset) or a negative
value (Keel Offset). The depth offset can be adjusted in 0.1 increments of the
units you have set for Depth Units: meters, fathoms, or feet. See Units on
page 4-8.

Speed Calibrate

If the transducer is equipped with a speed paddle wheel, the fishfinder
calculates and displays the speed of the boat through the water. The speed
calibrate option enables you to adjust the displayed speed so that it matches
your actual speed through the water. You can adjust the displayed speed from
1% to 200%.
If the Fishfinder reading is too low, set Speed Calibration to more than 100%.
If the Fishfinder reading is too high, set Speed Calibration to less than 100%.

Temperature Calibrate

The fishfinder calculates and displays the temperature of the water. The
temperature calibrate option enables you to adjust the displayed temperature.
You can adjust the displayed temperature by -9.0°F to +9.0°F.

Sonar History

Sonar History determines the number of data sample columns that appear on
the screen at one time. The options are: SMALL, which displays 240 columns of
data or LARGE, which shows 480 columns. Information displayed in a single
column using the LARGE setting would occupy two columns with SMALL. As a
result, twice as much data history is displayed under the LARGE setting. Data
displayed using SMALL appears wider and scrolls across the screen faster.
The default setting is LARGE.

Sonar Interference Rejection

Two or more sonar-equipped vessels operating within range of each other
can create interference on the sounder screen. This usually appears as ver-
tical streaks in the water that do not represent actual targets.
HD Series Fishfinders include a SONAR INT REJ option that reduces such
interference, either manually or automatically. LOW rejects only a small
amount of the extraneous objects. Use this setting when you want to be sure
that what has been removed are really false returns.
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