Speed Calibration. Maretron DSM250-01

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 77.

Figure 35 – Calibrating the Airmar Speed Transducer Speed

The speed calibration screen shown in Figure 77 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.

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