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4. Navigation:
− Which instrument is navigating? (See 12.6, C75)
− C75 (OFF) = The Server is navigating.
− C75 (ON) = The NMEA navigator is navigating.
− If problem with NMEA IN to Server, (see 12.7 and 12.6.4).
− If problem with NMEA OUT from Server, (see 12.6.7 and
12.6.5).
5. What you should know about digital depth sounders.
The principle of a depth sounder is that you measure the time it
takes for a short acoustic signal to go from the transducer to
bottom and back again to the transducer.
The echo changes due to bottom character, heavy layers of salt
and temperature, irregular bottom vegetation, fish etc. Thanks to
an advanced signal treatment, these variations will normally not
influence the depth measurement.
You can in some circumstances get transitory disturbances.
Below are listed some explanations for disturbances to the
measurement of depth and how it is expressed on the instrument
display.
1. There is no depth reading on the display. Only ( --- ) is
displayed:
If there are no depth echoes for 3 seconds, the display indicates 3
dotted lines ( --- ) until a new echo is received.
• In deep water outside the range of the transducer, or the
combination of deep water and soft bottom which makes it
difficult to reflect the signal.
• When the boat is heeling heavily, for example when sailing.
• In a propeller stream, where air bubbles are created. Example
when powering astern or when following close behind a power
boat.
• Check the connection at the amplifier box. Make sure the cable
is correct between, instrument and transducer, as marked on
the box.
• Internal mount with poor signal penetration due to a too thick
hull, (maximum thickness recommended is 20 - 30 mm) or air
between transducer and hull.
MAINTENANCE AND FAULT FINDING
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