Difference between revisions of "TrueWind"

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(calculate True Wind from Apparent Wind)
(simplified, assuming H=COG)
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* <b>AWA</b> Apparent Wind Angle (relative to H) <b>environment.wind.angleApparent</b>
 
* <b>AWA</b> Apparent Wind Angle (relative to H) <b>environment.wind.angleApparent</b>
 
* <b>AWS</b> Apparent Wind Speed <b>environment.wind.speedApparent</b>
 
* <b>AWS</b> Apparent Wind Speed <b>environment.wind.speedApparent</b>
 +
** <code>AWSx = AWS * Cos (AWA)</code>
 +
** <code>AWSy = AWS * Sin (AWA)</code>
 
** <b>TWA</b> True Wind Angle (relative to H=COG) <b>environment.wind.angleTrueGround</b>
 
** <b>TWA</b> True Wind Angle (relative to H=COG) <b>environment.wind.angleTrueGround</b>
** <code>...</code>
+
** <code>ATAN2(AWSy, -SOG + AWSx)</code>
 
** <b>TWS</b> True Wind Speed (relative to ground) <b>environment.wind.speedOverGround</b>
 
** <b>TWS</b> True Wind Speed (relative to ground) <b>environment.wind.speedOverGround</b>
** <code>...</code>
+
** <code>SQRT (POWER(AWSy,2) POWER(-SOG + AWSx,2))</code>
  
 
== see also ==
 
== see also ==

Revision as of 17:37, 29 October 2018

calculate True Wind from Apparent Wind

  • AWA Apparent Wind Angle (relative to H) environment.wind.angleApparent
  • H Heading (relative to true north) navigation.headingTrue
    • AWD Apparent Wind Direction (relative to true north) environment.wind.directionTrue
    • AWD = MOD(H+AWA;360)
  • AWS Apparent Wind Speed environment.wind.speedApparent
  • COG Course Over Ground navigation.courseOverGroundTrue
  • SOG Speed Over Ground navigation.speedOverGround
    • TWS True Wind Speed (relative to ground) environment.wind.speedOverGround
    • TWSx = SOG * Sin (COG) - AWS * Sin (AWD)
    • TWSy = SOG * Cos (COG) - AWS * Cos (AWD)
    • TWS= SQRT (TWSx*TWSx + TWSy*TWSy)
    • TWD True Wind Direction (relative to true north) ???
    • TWD = ATAN ( TWSx / TWSy )
  • STW Speed Trough Water navigation.speedThroughWater
    • DFT Current Drift (relative to ground) environment.current.drift
    • DFTx = SOG * Sin (COG) - STW * Sin (H)
    • DFTy = SOG * Cos (COG) - STW * Cos (H)
    • DFT= SQRT (DFTx*DFTx + DFTy*DFTy)
    • SET Current Set (relative to true north) environment.current.setTrue
    • SET = ATAN ( DFTx / DFTy )

simplified, assuming H=COG

  • COG Course Over Ground navigation.courseOverGroundTrue
  • AWA Apparent Wind Angle (relative to H) environment.wind.angleApparent
  • AWS Apparent Wind Speed environment.wind.speedApparent
    • AWSx = AWS * Cos (AWA)
    • AWSy = AWS * Sin (AWA)
    • TWA True Wind Angle (relative to H=COG) environment.wind.angleTrueGround
    • ATAN2(AWSy, -SOG + AWSx)
    • TWS True Wind Speed (relative to ground) environment.wind.speedOverGround
    • SQRT (POWER(AWSy,2) POWER(-SOG + AWSx,2))

see also