1. Vessels, assemblies of floating material and floating establishments under way or stationary (other than those specified in article 3.25) requiring protection against wash caused by the passage of other vessels or assemblies of floating material may, without prejudice to the marking applicable to them under the provisions of the other articles of this chapter, display:
By night:
An ordinary red light and an ordinary white light, or a bright red light and a bright white light, about 1 m one above the other with the red light above, and in such a position that they are clearly visible and cannot be confused with other lights;
By day:
A flag with a red upper half and the lower half white, in a suitable position and high enough to be visible from all directions. This flag may be replaced by two flags one above the other, the upper flag red and the lower flag white. These flags may be replaced by boards of the same colour.
2. Without prejudice to the provisions of article 3.25, only the following may use the marking mentioned in paragraph 1 above:
(a) Vessels, assemblies of floating material and floating establishments which are seriously damaged or are engaged in rescue work, and vessels unable to manoeuvre;
(b) Vessels, assemblies of floating material and floating establishments having written authorization from the competent authorities.