SET & DRIFT

SET AND DRIFT DETERMINATION

1) Plot DR using Speed, Distance, Time from last Fix.
  • See Speed/Distance/Time page
  • label with half circle, Time, and "DR"
  • label course line with Course (True bearing) over Speed (use C and S)
2) Plot FIX using bearings or electronics
  • label with full circle, Time, and "FIX"
3) Plot line from "DR" to "FIX"; the direction is the SET of the current.
  • label the True direction of the Set above the line with "SET="
4) Calculate Speed/Distance/Time for Speed, or DRIFT, on the DR/FIX line.
  • Time = time difference from last fix to DR (2hrs)
  • Distance = measured, with dividers on longitude, from DR to new FIX (4.2 miles)
  • Speed = speed of current in knots per hour, or DRIFT
    • Speed(drift) = 4.2/2=2.1
    • label below DR/FIX line with "DRIFT="