A vessel engaged in minesweeping shall carry, in addition to the marking prescribed elsewhere in these regulations:
By night:
Three bright or ordinary green lights visible from all directions, arranged in a triangle with a horizontal base in a plane perpendicular to the axis of the vessel, the top light at or near the top of the foremast and the other lights at each end of the foremast yard;
By day:
Three black balls arranged in the manner prescribed for the lights.