DEV – Deviascope


This examination is conducted practically and orally to a transport Canada inspector. It tests on the candidate’s ability to use a deviascope and/or an instructional binnacle. The exam requires the ability to create a deviation table, obtain approximate coefficients, the P, Q, and R components, their separate effects and their application to compensate for a ship’s magnetic field . The applicant must also demonstrate the ability to account for various magnetic errors such as retentive magnetism, Gaussin and heel errors.

To see a full list of requisite knowledge for the exam please refer to the exam’s Syllabus (Page 64, Section 5.7).

Recommended Reading:

Magnetic Compass Deviation and Correction by Denne, W.

In addition to dealing with the properties of magnets and the earth’s magnetism, three chapters are devoted to the magnetism of the ship, the third explaining in detail the reason for, and composition of, the “nine rods”. The relation of the components P, Q and R and the rods to the various coefficients are fully explained.

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