Maretron DSM150, User Manual

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Revision 1.4.18 Page 19
4.2.27 Wind
Apparent Direction
– displays the angle of the wind relative to the vessel center line as it
appears to an observer on the deck of a moving or stationary vessel (does not subtract out the
speed of the vessel)
Ground Direction
– displays the angle of the wind relative to true or magnetic north (depending
on the unit setting of the “heading” parameter, see Section 5.2.7.1) measured relative to a
stationary observer, calculated using heading, course over ground (COG), and speed over
ground (SOG)
True Direction
– displays the angle of the wind relative to the vessel center line (vessel‟s speed is
subtracted from Apparent wind direction), calculated using speed through water (STW) or
speed over gro
und (SOG) (depending on the unit setting of the “Wind True Vessel Ref.”
Parameter, see Section 5.2.7.6)
Apparent Speed
– displays the speed of the wind as it appears to an observer on the deck of a
moving or stationary vessel (does not subtract out the speed of the vessel)
Ground Speed
– displays the speed of the wind relative to a stationary observer, calculated using
heading, course over ground (COG), and speed over ground (SOG)
True Speed
– displays the speed of the wind as it would appear to an observer if the vessel was
stopped in the water, calculated using speed through water (STW) or speed over ground
(SOG) (depending on the unit setting of the “Wind True Vessel Ref.” Parameter, see Section
5.2.7.6)