ISO 20672:2022 pdf – Ships and marine technology — Rate of turn indicators.
1 Scope This document specifies the construction, performance requirements, methods of testing and required test results for the rate of turn indicators required by Clause 2.9.1, Regulation 19, chapter V, SOLAS 1974 (as amended, 2000). It is based upon the requirements of IMO Resolution A.526(13), and is also associated with IMO Resolution A.694 (17) and IEC 60945. Where a requirement in this document is different from that in IEC 60945, the requirement in this document takes precedence. NOTE All requirements that are extracted from the recommendations of IMO Resolution A.526(13) on performance standards for rate of turn indicators are printed in italics and the resolution and paragraph numbers are indicated in brackets. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60945, Marine navigation and radiocommunication equipment and systems — General requirements — Methods of testing and required test results IMO Resolution A.526(13), Performance standards for rate-of-turn indicators 3? Terms? and? definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminology databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at https:// www .electropedia .org/
3.1 rate of turn indicator indicator capable of indicating rates of turn in degrees per minute to starboard and to port of the ship to which it is fitted Note 1 to entry: A rate of turn indicator may be self-contained; alternatively it may form part of, or derive information from, any other appropriate equipment. [SOURCE: IMO Resolution A.526(13), 2.1 and 2.2, modified — in the definition, added “in degrees per minute”.] 3.2 analogue-type indicator indicator that shows the rate of turn in a continuous way, such as by means of an arrow pointer and a graduated scale
4.4 Illumination and lighting The illumination and lighting of the indicator shall be arranged in order not to hinder an operator’s vision at night and in order to make the scale, pointer and letters as equally visible as possible even in dim light or darkness. 4.5 Type of indicator The rate of turn indicator shall be an analogue-type indicator. A digital-type indicator may additionally be used, if fitted. If a display is used for presentation, the equipment shall comply with MSC.191(79), as amended by MSC.466(101), and IEC 62288. 4.6 Alert If the equipment is capable of raising an alert, it shall comply with MSC.302(87), IEC 62923-1 and IEC 62923-2. 5 Performance requirements 5.1 Accuracy a) [IMO Resolution A.526(13), 2.5.1] The indicated rate of turn shall not deviate from the actual rate of turn of the ship by more than 0,5° per minute plus 5 per cent of the indicated rate of turn of the ship. These values include the influence of earth rate. b) [IMO Resolution A.526(13), 2.5.2] Periodic rolling motion of the ship with an amplitude of ± 5° and period of up to 25 seconds and periodic pitching motion with an amplitude of ± 1° and period of up to 20 seconds shall not change the mean value of the indicated rate of turn by more than ± 0,5° per minute. c) [IMO Resolution A.526(13), 2.5.3] A rate of turn indicator shall meet these accuracy requirements at all ship speeds up to 30 knots. d) [IMO Resolution A.526(13), 2.4.3] The damping of the rate of turn indicators shall be provided with a time constant which may be varied during operation in the range zero to at least 10 seconds.