Question 33 TV02 - Towing Vessels - Great Lakes and Inland

The Correct Answer is B **Explanation for Option B (67.5°):** Option B, **67.5°**, is correct because it aligns precisely with the requirements for the stern light (or "white light showing astern") as defined by the International Regulations for Preventing Collisions at Sea (COLREGs), which are followed both internationally and by inland rules (usually adopting the same standard). According to Rule 21(d) of COLREGs, the stern light is defined as: > "a white light placed as nearly as practicable at the stern showing an unbroken light over an arc of the horizon of **135 degrees** and so fixed as to show the light 67.5 degrees from right aft on each side of the vessel." Therefore, the stern light must show from dead astern 67.5 degrees to port and 67.5 degrees to starboard, totaling 135 degrees. **Explanation for Incorrect Options:** * **A) 22.5°:** This arc is too narrow. 22.5° is the arc of visibility for the masthead light *forward* of the beam (on each side) where the sidelights stop showing. It is not the arc for the stern light. * **C) 112.5°:** This arc is too wide. 112.5° is the arc of visibility for the sidelights (the red port light and the green starboard light), which show from right ahead to 22.5° abaft the beam. * **D) 135.0°:** While 135° is the *total* arc of visibility for the stern light, the question asks how many degrees it shows on **each side** of the stern. The total arc (135°) must be divided into two equal parts (67.5° each).