1. (a)A sailing vessel underway shall exhibit sidelights and a sternlight.
2. (b)In a sailing vessel of less than 20 metres the sidelights and sternlight may be combined in one lantern at or near the top of the mast.
3. (c)A sailing vessel underway may in addition exhibit at or near the top of the mast two all-round lights in a vertical line, the upper red and the lower green, but not together with the combined lantern.
4. (d)A sailing vessel of less than 7 metres shall, if practicable, exhibit the above lights, but if not shall have ready at hand an electric torch or lighted lantern showing a white light in sufficient time to prevent collision; a vessel under oars may do the same.
5. (e)A vessel proceeding under sail when also being propelled by machinery shall exhibit forward a conical shape, apex downwards.