Note that the masthead tricolor can only be used under sail. When switching to power, must change to deck-mounted side lights.

Also it is illegal to run both deck and masthead side lights at the same time.

Rule 25(a)
A sailing vessel underway shall exhibit:
(i) sidelights;

(ii) a stern light.

(b) In a sailing vessel of less than 20 meters in length the lights prescribed in paragraph (a) of this Rule may be combined in one lantern carried at or near the top of the mast where it can best be seen.