You swung ship and compared the magnetic compass against the gyro compass to find deviation. Gyro error is 2° E. The variation is 8° W. Find the deviation on a gyro heading of 196°.
PSC PGC 030.5° 020° 092.0° 080° 106.5° 050° 122.5° 110° 152.0° 140° 181.0° 170° 210.0° 200° 239.5° 230° 269.0° 260° 298.0° 290° 327.5° 320° 358.5° 350°
• Relationship between True, Magnetic, and Compass headings (TVMDC formula) • How gyro error affects conversion between gyro and true headings • How to interpolate deviation between two known headings on a deviation table
• First convert the known gyro headings in the table to TRUE using the stated gyro error. What is the sign convention for a 2° E gyro error? • From TRUE, use the given variation (8° W) to find the corresponding MAGNETIC headings. How does W variation affect the conversion? • Once you know magnetic and compass headings, use them to determine deviation at nearby headings and interpolate to find deviation near a gyro heading of 196°.
• Be clear on whether East errors are added or subtracted when going from True to Gyro and from Gyro to True. • Confirm the correct direction for applying 8° W variation when moving between True and Magnetic headings. • When estimating deviation at 196° gyro, check that you use the two closest headings from the table and interpolate logically between them.
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