Garmin GPSMAP 235 Sounder - Manual (Page 46)

Sounder Setup Page (con’t.)
There are four options:
• 200 kHz: Best suited for shallow, inland waters where deep water performance is
not critical and bottom detail and resolution is the highest priority.
• 50 kHz: For maximum deepest readings. Note: Maximum readable depths in salt-
water will be 25% - 50% less than freshwater depths, because of saltwater attenua-
tion of the sonar signal.
• 200/50 kHz: Allows you to operate with two frequencies for maximum depth read-
ings with good bottom detail and resolution. When the split screen is displayed,
the bottom frequency (in this case, 50 kHz) is always shown on the bottom screen.
• 50/200 kHz: For viewing versatility, select 50/200 kHz which will allow you to
view the 200 kHz setting in the bottom screen.
To select a transducer frequency:
1. Highlight the ‘Frequency’ field and press T . Use the R to select a frequency
and press T .
• Speed Calibration: If you are using a transducer capable of displaying speed
through water (STW), calibration is required to ensure that the STW displayed by
the sounder will be accurate. The unit can be calibrated automatically or manually,
but auto calibration is recommended (the default setting).
To calibrate the unit:
1. Press O to display the sounder options page.
2. Using the R keypad, highlight ‘Sounder Setup?’ and press T .
3. Choose between auto and manual calibration (COG field).
36
SECTION
3
SOUNDER PAGE
Transducer Frequency
and Speed Calibration
Setup
A B
A. The 200 kHz/50 kHz selection gives you maxi-
mum depth readings with good bottom detail and
resolution.
B. Calibration is required if you are using a trans-
ducer capable of displaying speed through the
water.
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