Alignment of heading marker
25. The radar heading marker (and stern marker is fitted) shall be aligned to within 1° of the ship’s fore-and-aft line as soon as practicable after the radar installation has been installed in the ship. Where inter-switching facilities are provided, the heading marker shall be aligned with all arrangements of units. The marker shall be re-aligned as soon as practicable whenever it is found to be substantially inaccurate.