POV: HOW TO CALCULATE GYRO ERROR BY POLARIS ✨

Here is the step-by-step method used on ships to calculate Gyro Error using the star Polaris.

Polaris is very useful because it is located almost directly above True North, so its true bearing is very close to 000°T.

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Step-by-Step: Gyro Error by Polaris ⭐

1️⃣ Observe Polaris

At night, locate Polaris (North Star) using the Big Dipper or Ursa Major.

Take the bearing of Polaris using the gyro compass repeater.

Example observation:

Gyro Bearing (GB) = 358° G

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2️⃣ Note the Time of Observation

Record the exact UTC time when the bearing was taken.

Example:

Time = 21:10 UTC

This is needed to get LHA Aries from the nautical tables.

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3️⃣ Get LHA Aries from Nautical Almanac

Using the Nautical Almanac, find the Greenwich Hour Angle (GHA) of Aries at the time of observation.

Example:

GHA Aries = 120°

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4️⃣ Calculate LHA Aries

Formula:

LHA\ Aries = GHA\ Aries + Longitude

If longitude is East, subtract.
If longitude is West, add.

Example:

Longitude = 20°W

LHA = 120° + 20°

LHA = 140°

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5️⃣ Use the Polaris Table

Open the Polaris table in the Nautical Almanac.

Enter with:
• LHA Aries
• Observer’s Latitude

Example:

Latitude = 15°N
LHA Aries = 140°

From the table you obtain the True Azimuth (Zn) of Polaris.

Example result:

True Bearing of Polaris = 359°T

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6️⃣ Compare True Bearing and Gyro Bearing

Formula:

Gyro\ Error = True\ Bearing - Gyro\ Bearing

Example:

True Bearing = 359°T
Gyro Bearing = 358°G

GE = 359° - 358°

GE = +1°

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7️⃣ Determine East or West Error

Rule:
• True Gyro → East Error
• True Gyro → West Error

Example:

359° − 358° = +1°

✅ Gyro Error = 1° East

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Final Result

Gyro Error = 1° E

Thank you! #ConcernedProfessor

#fyp #polariscalculation #SEAMAN

Видео POV: HOW TO CALCULATE GYRO ERROR BY POLARIS ✨ канала Prof. Kris Minion