(a) A vessel engaged on pilotage duty shall exhibit:
(i) at or near the masthead Rule 21. (a)"Masthead light" means a white light placed over the fore and aft centerline of the vessel showing an unbroken light over an arc of the horizon of 225 degrees and so fixed as to show the light from right ahead to 22.5 degrees abaft the beam on either side of the vessel, except that on a vessel of less than 12 meters in length the masthead light shall be placed as nearly as practicable to the fore and aft centerline of the vessel. [Inld], two all-round Rule 21. (e) "All-round light" means a light showing an unbroken light over an arc of the horizon of 360 degrees. lights in a vertical line, the upper being white and the lower red;
(ii) when underway Rule 3. (h/i)The word "underway" means that a vessel is not at anchor, or made fast to the shore, or aground., in addition, sidelights Rule 21. (b)"Sidelights" means a green light on the starboard side and a red light on the port side each showing an unbroken light over an arc of the horizon of 112.5 degrees and so fixed as to show the light from right ahead to 22.5 degrees abaft the beam on its respective side. In a vessel of less than 20 meters in length the sidelights may be combined in one lantern carried on the fore and aft centerline of the vessel, except that on a vessel of less than 12 meters in length the sidelights when combined in one lantern shall be placed as nearly as practicable to the fore and aft centerline of the vessel. [Inld] and a sternlight Rule 21. (c)"Sternlight" means a white light placed as nearly as practicable at the stern showing an unbroken light over an arc of the horizon of 135 degrees and so fixed as to show the light 67.5 degrees from right aft on each side of the vessel.;
(iii) when at anchor, in addition to the lights prescribed in subparagraph (i), the light, lights, or shape prescribed in Rule 30 for [vessels at anchor / anchored vessels].
(b) A pilot vessel when not engaged on pilotage duty shall exhibit the lights or shapes prescribed for a similar vessel of her length Rule 3. (j/i)The words "length" and "breadth" of a vessel mean her length overall and greatest breadth..