SEA CALCULATOR
Gyro & compass error
Celestial and compass worksheet: observed bearing, gyro error, and true / magnetic / compass courses.
Example values — edit any field; results update as you type.
Position, date & time
Decimal: 1.266667°
Degree and minute fields with N/S/E/W.
Decimal: 103.833333°
Degree and minute fields with N/S/E/W.
Ephemeris uses UTC — convert from bridge time if needed.
Observed readings
°G
°G
°
Chart variation; east is positive.
Var E/W
°
Ship’s deviation from the deviation card; east positive.
Dev E/W
Result
- Body / star
- Sun
- True azimuth Zn
- 91.68°T
- Altitude
- 30.87°
- Gyro error
- 3.82° W
- Gyro course
- 45.0°G
- True course
- 41.18°T
- Variation
- 0.5° E
- Magnetic course
- 40.68°M
- Deviation
- 1.2° W
- Compass course
- 41.88°C
- Compass error
- 0.70° W