What is a navigational aid?

A navigational aid refers to any device, structure, or technology that assists mariners in determining their position, navigating safely, and avoiding hazards at sea. This includes range markers, buoys, lighthouses, radar systems, GPS devices, and other visual or electronic aids that provide crucial information to help with navigation. The primary purpose of navigational aids is to enhance safe and effective passage through waterways, making option C the correct answer.

Understanding navigational aids is essential for effective seamanship, as they facilitate safe navigation by indicating safe passage, potential dangers, and guiding vessels to their destinations. The other options, while related to maritime activities, do not fall under the definition of navigational aids as they focus on different aspects such as weather information, fuel calculations, or ship design rather than navigation itself.