Under Rule 18, which vessels are required to keep out of the way of vessels constrained by their draft?

Answer: D — All other vessels

The correct answer is that all other vessels are required to keep out of the way of vessels constrained by their draft. Rule 18 of the COLREGs outlines the responsibilities of different types of vessels when they encounter one another. A vessel constrained by its draft refers to a situation where a ship's draft (the vertical distance between the waterline and the bottom of the hull) limits its ability to maneuver freely, often in shallow waters or narrow channels. This rule is designed to ensure safety on the water by establishing that other vessels, regardless of their type—whether they are power-driven, sailing, or engaged in fishing or towing—must give way to the constrained vessel. This is important because a vessel constrained by its draft has less ability to maneuver and could be at risk of grounding or colliding if other vessels do not yield appropriately. All vessels must exercise caution and maintain a safe distance from these kinds of vessels to prevent accidents. Understanding this rule helps mariners navigate safely in various maritime situations, particularly in proximity to larger ships that may be unable to alter their course effectively.