Your vessel is steering course 027° per standard magnetic compass (psc), variation for the area is 19°W, and deviation is 2°E. The wind is from the north-northwest, producing a 5° leeway. What true course are you making good?
• Compass to true conversion sequence (Compass → Magnetic → True) • Effect of variation (west) and deviation (east) on the compass course • How leeway (from NNW) will push the vessel off course and how to apply it (add or subtract)
• Start with the course per standard magnetic compass (psc) and carefully convert it step-by-step to a true course, keeping track of each correction sign. • Think about the saying for applying variation and deviation (for example, whether you add or subtract west variation and east deviation when going from compass to true). • Visualize the wind direction from NNW and your heading to decide which way the wind will push your vessel and whether that makes the true course to be made good larger or smaller.
• Be sure of the order of corrections from compass to true: are you going C → M → T or T → M → C? • Double-check the signs of variation and deviation (west vs east) when converting to true – a wrong sign will give an obviously wrong answer. • Confirm the direction of leeway: is the vessel being pushed to the right or left of the intended heading, and should that make your final true course higher or lower in degrees?
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