| (1) |
Paper 1 (two hours written) |
| (a) |
Properties of magnets: Meaning of terms "Hard" and "Soft" iron, magnetic induction and permeability. |
Effects of magnets on a compass needle under varying conditions. Knowledge of fields of magnets. Disturbing and restoring couples.
position of equilibrium. Molecular theory of magnetism. Magnetic effects of electrical currents.
| (b) |
Terrestrial magnetism: Variation, dip, total force, horizontal force, vertical force. local attraction: Their varying strengths in different parts of the globe and their various effects on deviation. |
| (c) |
Ship's magnetism: Effects of permanent and induced magnetism. Components P, Q and R; the rods a, b, c, d, e, f, g, h and k. Sub-permanent magnetism and its effects at sea. |
| (d) |
Compass design: General principles, with special reference to the following: |
| (i) |
Size and relative positions of compass needles; |
| (Ii) |
location of soft iron correctors and permanent magnets, with reference to each other and to the compass needles, with due regard to standard binnacles of all types, overhead compasses and pole compasses, and the probable effects if conventional limits are not complied with; |
| (iii) |
relative position of lubber mark, card, pivot and gimbal axes; and |
| (iv) |
types of quadrantal correctors used in South Africa and on foreign ships – their advantages and disadvantages. |
| (e) |
The siting and lining up of compasses with due regard to the proximity of magnetic material, electrical devices and other disturbing influences. Magnetic screening. Meaning of ʵ (lambda), µ (mu) and ship's multiplier. How to find and use these quantities. |
| (2) |
Paper 2 (three hours written) |
| (a) |
Compass compensations: Various methods of swinging ship to obtain a deviation table. Construction of a curve of deviations and its practical use in coefficient analysis. Constant, semi-circular and quadrantal deviation. Analysis of the deviation book of a foreign-going ship to determine causes of irregular deviations and suggest measures for their removal. Analysis of a table of deviation, obtaining and explaining the approximate coefficients A, B, C, D and E. |
| (b) |
General principles of compass correction and methods of finding and compensating for A, B, C, D, E types of deviation. The relation of the components P, Q and R and the rods including calculations a, b, c, d, e, f, g, h and k to the various coefficients and to heeling error. |
| (c) |
Compensation by use of the Kelvin deflector. Principle of the deflector method and information which can be deduced from the readings. Limits of accuracy of results obtained. Rules to be followed with regard to the placing of correctors. Questions on "Wiping" and degaussing so far as they effect magnetic compasses. |
| (3) |
Oral examination, in which— |
| (a) |
candidates will be required to demonstrate on a deviascope or compass binnacle the principle of compass adjustment. They will be required to adjust a dry compass or a spirit compass using the vertical force instrument in the correction of heeling error. They will be required to have a thorough knowledge of the methods of detecting faults in instruments, such as sagged needles, cracked sapphires, bent or damaged pivots, hairs on edge of dry card, faulty binnacles, spheres too high or too low, Flinders bar wrong height, bowls not free gimbals, faulty heeling error conditions,and how such faults should be dealt with; |
| (b) |
candidates must be able to demonstrate how a mass of soft iron would be magnetised while lying in the earth's magnetic field in different parts of the world or while under the influence of permanent magnets; |
| (c) |
candidates will be required to have a knowledge of the different methods of taking bearings and of using and testing a pelrous and an azimuth mirror; |
| (d) |
practical tests may also be required on matters such as safe distances of equipment in the of the compass, e.g. electric helm indicators, loud hailers, steel tanks and electrical earth; the use of the Kelvin deflector in compass adjustment; the use of the oscillating magnetometer to find 2 ʵ (lambda); the relation between a master (or pilot) and the adjuster; |
| (e) |
the examiner may ask any other questions part of the examination. |
| (4) |
In the practical part of the examination the candidate will be required to— |
| (a) |
perform the adjustment of a ship's magnetic compass in the presence of the examiner who will monitor the method of adjustment used and the accuracy of the results (Note: the candidate may seek the assistance of the examiner in arranging for a suitable ship to be made available for this purpose); |
| (b) |
use the full analysis method, determining the deviations with reference to— |
| (i) |
the magnetic bearing of a distant object, or |
| (ii) |
pre-computed bearings of a heavenly body the discretion of the examiner;and |
| (c) |
adjust the compass by the deflector method at the discretion of the examiner. |
Minister of Transport.
Statistics Act, 1999
