BOTH INTERNATIONAL & INLAND What light(s) must sailboats 20 meters in length show when underway at night?

Correct Answer: Option D — Red and green sidelights and a stern light

Rule 25(a) mandates that a sailing vessel underway must exhibit sidelights and a stern light. These lights are essential for indicating the vessel's heading and presence to other traffic at night, ensuring compliance with the basic requirements for navigation safety under the International and Inland Rules of the Road.