This part of ISO 22090 specifies the construction, performance and testing of devices employing only
magnetic means as transmitting heading devices required by chapter V, SOLAS 1974 (as amended).
A Transmitting Heading Device (THD) is an electronic device that provides information about the ship’s true
heading.
In addition to the general requirements contained in IMO Resolution A.694(17) to which IEC 60945 is
associated and the relevant standard for the sensing part used, the THD equipment shall comply with the
following minimum requirements.
Where the IMO performance standards which apply to the sensing part do not specify a geographical
operating area the THD shall operate
a) at a minimum rate of turn 20 °/s, and
b) from 70° latitude south to 70° latitude north as a minimum.
The THDs complying with the requirements contained in this part of ISO 22090 can be used for heading
information as contained in Chapter V of the SOLAS Convention.
In addition such THDs should meet the dynamic requirements contained in the HSC Code, chapter 13 for the
carriage of a suitable device providing heading information.
NOTE 1 Several technologies can be used to detect and transmit heading information. It is illogical to standardize the
detection of the heading separately from the transmission of the heading. Therefore, separate parts of this part of
ISO 22090 refer to different technologies. The requirements of this part of ISO 22090 only apply to the principle of the
Geomagnetic one. Other technologies are covered in other parts of ISO 22090.
NOTE 2 All requirements that are extracted from the recommendation of IMO Resolution MSC. 116 (73) on
performance standards for transmitting heading devices are printed in italics.
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. Nevertheless, when the THD would be only used other
than the HSC, the limit of rate of turn may be 6°/s instead of 20°/s .
ISO 22090-2:2004 history
2014ISO 22090-2:2014 Ships and marine technology - Transmitting heading devices (THDs) - Part 2: Geomagnetic principles
2005ISO 22090-2:2004/Cor 1:2005 Ships and marine technology - Transmitting heading devices (THDs) - Part 2: Geomagnetic principles; Technical Corrigendum 1
2004ISO 22090-2:2004 Ships and marine technology - Transmitting heading devices (THDs) - Part 2: Geomagnetic principles