The THD generates a heading signal and outputs a suitable signal for other devices.
Any sensing part defined in 3.3 may be included in the device.
If any correcting devices or parameters have been associated, they shall be protected against inadvertent operation.
Manually entered values used for electronic correction shall be indicated by adequate means.
Gyro-compass units shall conform to the following requirements.
4.2 Continuous operation
The equipment shall be capable of continuous operation under conditions of vibration, humidity, change of temperature and variations of the power supply, as specified in 6.10.
4.3 Information
All displays with the exception of the sensor, and all outputs of heading shall indicate true heading.
Indication shall be displayed with readable tenth of a degree.
4.4 Fore and aft mark
The compass shall be marked to facilitate installation in fore and aft line of the ship.
4.5 Speed error correction
Means shall be provided for correcting the errors induced by speed and latitude. An approved accurate speed source shall be used for automatic speed error corrections.
4.6 Heading information
The THD shall be provided true heading information to the other navigational aids.
Heading information shall provide with an output with an accuracy as defined in 5.2.6.
At least one output shall be in accordance with the relevant international marine interface standard, IEC 61162 series.
4.7 Status indication
Status shall be indicated that the Gyro-compass is ready to use.
4.8 Alarm signal
An alarm shall be provided to indicate malfunctions of the THD or a failure of the power supply.
5 Accuracy
The THD shall meet at least the following accuracy at the output of the device under sea conditions as specified in IMO Resolution A.424 (XI) or A.821 (19) as applicable.
5.1 Accuracy of transmission data
The transmission error including the resolution error shall be less than ±O.2°.
5.2 Accuracy under static conditions
5.2.1 Settling time under static conditions
When switched on in accordance with the manufacturer's instructions, the compass shall settle within 6 h.
5.2.2 Static error (Settle point error)
5.2.2.1 The static error (settle point error) as defined in 3.7 at any heading shall be less than ±1,0°× secant latitude, and the RMS value of the differences between individual heading indications and the mean value shall be less than ±0,35°× secant latitude.
5.2.2.2 The repeatability of settle point error from one run-up to another shall be within 0,35°× secant latitude.
