4.1.2 The accuracy of the fore-and-aft mark should be within ± 0.5°to the fore-and-aft direction of the housing.
4.l.3 If a rate gyro is installed it should be marked in the same way and additionally be marked with top or bottom.
4.2 Fitting
4.2.1 Provision should be made, in the mounting arrangements of the magnetic sensor, for correction of any misalignment, up to ± 5°, with respect to the fore-and-aft line.
4.2.2 The fitting of the sensor arrangement to the compass in paragraph 3.1 above should still enable the compass to comply with resolution A.382(X)with particular reference to accuracy, gimbling and use of the azimuth reading device.
4.3 Compensation of deviation and heeling error
Provision should be made to correct the deviation and heeling error and it should be possible to correct to the following values：*
.3.1 vertical component of the ship's magetic field (producing the heeling error)：
up to ±75 μT;
.3.2 coefficient A： up to ±3°;
.3.3 coefficient B： up to ±(720/H)°;
.3.4 coefficient C： up to ±(720/H)°;
.3.5 coefficient D： up to ±7°; and
.3.6 coefficient E： up to ± 3°,
where H is the horizontal component of the geomagnetic flux density in microteslas (μT)
4.3.1 Indication of compensation
The values used for electronic compensation should be indicated by adequate means and should be stored such that values are automatically recovered on switch-on.
4.3.2 Protection of compensation
The compensating devices should be protected against inadvertent operation.
* ISO 11606
