1. Floating equipment at work and stationary vessels carrying out work or sounding or measuring operations shall carry:
(a) On the side or sides on which the fairway is clear:
By night:
Two ordinary green lights or two bright green lights, positioned at a height of about 1 m one above the other;
By day:
Two green bicones, placed about 1 m one above the other;
and, as appropriate;
(b) On the side on which the fairway is not clear:
By night:
An ordinary red light or a bright red light, placed at the same height as the higher of the two green lights prescribed in (a) above, and of the same intensity;
By day:
A red ball, placed at the same height as the higher of the two green bicones prescribed in (a) above,
or, if the vessels have to be protected against wash,
(c) On the side or sides on which the fairway is clear:
By night:
An ordinary red light and an ordinary white light, or a bright red light and bright white light, placed about 1 m one above the other, with the red light at the top;
By day:
A flag with a red upper half and a white lower half, or two flags flown one above the other, the upper flag being red and the lower flag white,
and, as appropriate,
(d) On the side on which the fairway is not clear:
By night:
A red light at the same height and of the same intensity as the red light prescribed in (c) above;
By day:
A red flag at the same height as the red and white flag or red flag flown on the other side.
2. The marking prescribed by day in paragraph 1 (a) and (b) above may be replaced by the following signs:
(a) On the side or sides on which the fairway is clear, the “entry permitted” board E.1 (annex 7);
and, as appropriate,
(b) On the side on which the fairway is not clear, the “no entry” board A.1 (annex 7), placed at the same height as the board prescribed in (a) above.
3. The marking prescribed in paragraphs 1 and 2 above shall be placed high enough to be visible from all directions.
The flags may be replaced by boards of the same colour.
4. Grounded or sunken vessels shall carry the marking prescribed in paragraph 1 (c) and (d) above. If the position of a sunken vessel prevents the marking from being placed on the vessel, it shall be placed on boats or buoys or displayed in any other appropriate manner.
5. The competent authorities may waive the obligation to carry the lights prescribed in paragraphs 1 and 2 above under (a) and (b).