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13 STANDARDS FOR DEVICES TO INDICATE SPEED AND DISTANCE

13.1 INTRODUCTION 

13.1.1 Devices to indicate speed and distance required by the Navigating Appliances and Equipment Regulations are intended for general navigational use to provide information on the distance run and the forward speed of the ship, through the water or over the ground. The equipment shall function at forward speeds up to the maximum speed of the ship and in water of depth greater than 3 metres beneath the keel.

13.2 METHODS OF PRESENTATION ^

13.2.1 Speed information may be presented in either analogue or digital form. Where a digital display is used, its incremental steps shall not exceed 0.1 knots. Analogue displays shall be graduated at least every 0.5 knots and be marked with figures at least every 5 knots. If the display can present the speed of the ship in both forward and reverse directions, the direction of movement shall be indicated unambiguously.

13.2.2 Distance run information shall be presented in digital form. The display shall cover the range from 0 to less than 9999.9 nautical miles and the incremental steps shall not exceed 0.1 nautical mile. Where practicable, means shall be provided for resetting a readout to zero.

13.2.3 The display shall be easily readable by day and by night.

13.2.4 Means shall be provided for feeding distance run information to other equipment fitted on board. The information shall be in the form of one contact closure or the equivalent for every 0.005 nautical miles run.

13.2.5 If equipment is capable of being operated in either the "speed through the water" or "speed over the ground" modes, mode selection and mode indication shall be provided.

13.3 ACCURACY OF MEASUREMENT ^

13.3.1 Errors in the indicated speed, when the ship is operating free from shallow water effect, and from the effects of wind, current and tide shall not exceed 5 per cent of the speed of the ship, or 0.5 knots, whichever is the greater.

13.3.2 Errors in the indicated distance run, when the ship is operating free from shallow water effect, and from the effects of wind, current and tide shall not exceed 5 percent of the distance run by the ship in one hour or 0.5 nautical miles in each hour, whichever is the greater.

13.3.3 If the accuracy of devices to indicate speed and distance run can be affected by certain conditions (e.g. sea state and its effects, water temperature, salinity, sound velocity in water, the depth of water under the keel, heel and trim of ship), details of possible effects shall be included in the equipment handbook.

13.4 ROLL AND PITCH ^

13.4.1 The performance of the equipment shall be such that it will meet the requirements of these standards when the ship is rolling up to plus or minus 10 degrees and pitching up to plus or minus 5 degrees.

13.5 CONSTRUCTION AND INSTALLATION ^

13.5.1 The system shall be so designed that neither the method of attachment of parts of the equipment to the ship nor damage occurring to any part of the equipment which penetrates the hull could result in the ingress of water to the ship.

13.5.2 Where any part of the system is designed to extend from and retract into the hull of the ship, the design shall ensure that it can be extended, operated normally and retracted at all speeds up to the maximum speed of the ship. Its extended and retracted positions shall be clearly indicated at the display position.

13.6 INTERNATIONAL STANDARD ^

13.6.1 The International Maritime Organization Resolution "A.478(XII) Performance Standards for Devices to Indicate Speed and Distance" is the adopted standard.

13.7 EFFECTIVE DATE ^

13.7.1 This Standard comes into force on 1 September 1985.

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