Chapter 2: Setting Up Graphic Displays 7-2-27
ST290 Instrument System Owner’s Handbook
3. Calculate the actual speed over the measured distance.
• If this is the same as the indicated speed, calibration is correct at
this speed, so proceed from Manual calibration step 5.
• If the true speed is not the same as the indicated speed:
i. Calculate a new, corrected calibration factor, as follows
ii. Hold down the button for 1 secondto enter edit mode. The
highlighted calibration factor value field flashes
iii. Use the or button to change the highlighted calibration
factor value, to the new value, then hold down the button
for 1 second.
4. Repeat Manual calibration steps 2 and 3, until the indicated SPEED is
the same as the actual speed.
5. Use the or button to highlight the calibration factor value field
for the next calibration speed.
6. Repeat Manual calibration steps 2 to 5, until all calibration factor val-
ues are correct.
Depth transducer offset
WARNING:
The use of incorrect depth offset values could result in misleading
depthinformationbeingdisplayedwithaconsequentriskofrunning
aground.
Depths are measured from the Depth transducer to the seabed. However,
you can apply an offset to the actual distance measured so that the
displayed depth reading represents either the depth from the waterline or
from the bottom of the keel (see Figure 2-25 ).
new calibration factor =
measured speed
true speed x old calibration factor
81183_2 S7.book Page 27 Wednesday, May 7, 2003 1:52 PM
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