1. A vessel which is unable to manoeuvre shall, if necessary, display, in addition to the marking prescribed elsewhere in these regulations:
By night:
A swinging red light; in the case of small craft, this light may be white instead of red; or
Two red lights, one about 1 m one above the other, placed in a suitable position and high enough to be visible from all directions;
By day:
A swinging red flag; or
Two black balls, one about 1 m one above the other, placed in a suitable position and high enough to be visible from all directions.
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