Section 12 in The Merchant shipping (Radio Direction Finders) Rules, 1968.
12. Calibration.
(1)The Master of every ship shall cause the radio direction finder to be calibrated in accordance with this rule as soon as practicable after it has been installed in the ship and whenever any change is made in the position of the radio direction finder aerial system.(2)The radio direction-finder shall be calibrated by two persons the one being experienced in the taking of radio bearings and the other experienced in the taking of visual bearings. The calibration shall be carried out by taking simultaneous radio and visual bearings of a calibrating transmitter, and such bearings shall be taken at intervals of not greater than 5 degrees throughout 360 degrees on a frequency between 285 Kc/s and 315 Kc/s.(3)Calibration tables and curves shall be prepared on the basis, if the bearings taken in accordance with sub-rule (2).(4)The Master of every ship shall cause the calibration tables and curves prepared in accordance with the foregoing provisions of this rule to be verified by means of check-bearings"(a)at intervals not exceeding twelve months; and(b)whenever any change is made in any structure or fitting on deck which is likely to affect the "accuracy of the radio direction-finder.If such verification shows that the calibration tables or curves are materially inaccurate, the Master of the ship shall cause the radio direction-finder to be recalibrated as soon as practicable in the manner specified in sub-rules (2) and (3).
