DIN ISO 22090-2:2013-01

A transmitting heading device (THD, True Heading Device) serves for the detection and transmission of heading information necessary for navigation of watercraft. It is an electronic device providing information about the ship's true heading. The true heading indicates the angle between the direction of motion of the ship and geographic north (reference direction). The terms are specified in DIN 13312 "Navigation - Concepts, abbreviations, letter symbols, graphical symbols". A True Heading Device can operate on the basis of various technologies. DIN ISO 22090 "Ships and marine technology - Transmitting heading devices (THDs)" consists of - Part 1: Gyro-compasses - Part 2: Geomagnetic principles - Part 3: GNSS principles The standards contain the technical requirements and, in addition to the general requirements contained in IEC 60945 and IMO resolution A.694 (17), further requirements for the application of the respective device on high speed craft (HSC). This part of ISO 22090 specifies the construction, performance and test requirements of devices operating by analysis of geomagnetic data as transmitting heading devices as required by chapter V, SOLAS 1974 (as amended). Other methods are dealt with in the other two parts of ISO 22090. A standard magnetic compass with a pickup sensor could be applied as a sensing part of this standard of geomagnetic principle. However the IMO performance resolution MSC.116(73) requires that the THD should be met for the dynamic requirements of the HSC code.