Furuno DS-85 Operator's Manual page 27

Display example
Speed through the water (STW)
Note: As a remedy, change the echo reference setting to
a large number such as 9 (see section 1.11.4).
Speed over the ground (SOG)
Display example: GLONASS
Note: When the ship's speed source is "AUTO" and SOG
input is lost, the error message will be for STW, not SOG.
Abnormal temperature at transducer
If any abnormal speed indication or abnormal temperature continues to occur, contact your dealer
for advice.
Speed error and abnormal temperature at transducer
Last correct speed is
displayed, however the
displayed value is
frozen.
Speed unit is high-
lighted in yellow.
Speed is shown
as "--.--"
Speed unit is high-
lighted in yellow.
Speed is shown
as "--.-"
Abnormal transducer
temperature icon
Ship's speed cannot be calculated for
30 seconds, because of air bubbles,
etc.
• Transducer error or air bubbles on
the transducer.
• Speed error continues for more than
30 seconds.
• GLONASS data error.
• GLONASS receiver disconnected.
• No GLONASS data received for 30
seconds.
Abnormal temperature found at trans-
ducer.
16
2. MAINTENANCE
Probable cause