Maretron DSM150, User Manual

Page: 64 / 274

DSM150
User’s Manual
Page 48 Revision 1.4.18
such that all subsequent measured STW readings are no longer adjusted before begin transmitted
over the NMEA 2000
®
network.
6.1.6 Speed Calibration
The Airmar speed transducer speed through water (STW) initial accuracy is significantly affected by
the location or placement of the speed transducer within the hull. The speed transducer can be
corrected for these inaccuracies using the speed calibration procedure. You calibrate the speed
transducer STW by pressing the
Enter key (
) with the “Speed Calibration…” menu item selected
which results in the screen shown in Figure 74.
Figure 32
– Calibrating the Airmar Speed Transducer Speed
The speed calibration screen shown in Figure 74 indicates the STW as measured by the Airmar
speed transducer, which can be changed to the transmitted STW by following these steps. First, pick
a speed where you are most concerned with the best accuracy. Next, bring the boat up to the desired
speed using some other source, perhaps the GPS speed over ground (SOG). Remember that the
SOG does not necessary reflect the STW because of currents, and drift due to winds, so you should
do this in an area where you are sure there are no currents and calm winds. Finally, use the Increase
(
) and Decrease ( ) keys to adjust the display value until it matches the known speed of the
boat. Press the Accept ( ) key to accept the value when you are satisfied. If you do not wish to
perform speed calibration at this time, press the Abort ( ) key and the speed calibration will not be
altered.
6.1.7 Clear Temperature Offset
The Clear Temperature Offset configuration parameter shows you the currently used temperature
correction offset. All measured sea temperature readings have this value added to them before being
transmitted over the NMEA 2000
®
network. You can set the correction offset to zero by pressing the
Enter key (
) with the “Clear Speed Calibration:” menu item selected. And then choose “Clear”
using Scroll Up ( ) or Scroll Down ( ) keys followed by the Enter key ( ). This changes the
correction factor back to 0 such that all subsequent measured sea temperature readings are no
longer adjusted before begin transmitted over the NMEA 2000
®
network.