Marine navigation courses: compass navigation - The Diigo Meta page

• 26 Jul 13
  

  Dave Miller

  •  From the image we find: tc = cc + var
     in which “cc” and “tc” stand for “compass course” and “true course”, respectively. 

  • To convert a true course into a compass course we need first assign a “-” to a Western and a “+” to a Eastern variation. Note that this makes sense! because of the clockwise direction of the compass rose. Here, the inner circle is turned 10° anticlockwise, hence -10°. 
     Now, use the same but re-written equation: 
      cc = tc - var
     235° = 225° - (-10°)   
     So, to sail a true course of 225°, the helmsman has to steer a compass course of 235°.   
     
• 22 May 07
  

  Mark Vickers

  Marine compasses and magnetic deviation and variation. The proven method of navigating by magnetic compass courses: 3-marine compass.

  imported Leisure Boats SailingInstruction

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