Seaman's Handbook

PART C. Lights and Shapes : Pilot vessels

(a) A vessel engaged on pilotage duty shall exhibit:
  1. at or near the masthead, two all-round lights in a vertical line, the upper being white and the lower red:
  2. when underway, in addition, sidelights and a sternlight;
  3. when at anchor, in addition to the lights prescribed in sub-paragraph (i), the light, lights or shape prescribed in Rule 30 for vessels at anchor.
(b) A pilot vessel when not engaged on pilotage duty shall exhibit the lights or shapes prescribed for a similar vessel of her length.