BOTH INTERNATIONAL & INLAND In the daytime, you see a large sailing vessel on the beam. You know that she is also propelled by machinery if she shows which shape?

Correct Answer: Option D — a black cone

Rule 25(e) mandates that a vessel proceeding under sail when also being propelled by machinery shall exhibit forward, where it can best be seen, a conical shape, apex downwards. This shape informs other mariners that the vessel is considered power-driven under the COLREGS and Inland Rules.