What does the term "course over ground" (COG) define?

The term "course over ground" (COG) refers specifically to the actual path a vessel travels over the seabed, reflecting the vessel's trajectory in relation to the Earth’s surface. This measurement takes into account factors such as currents, wind, and water depth, allowing for an accurate understanding of where the ship is truly headed, regardless of its heading or navigation instruments.

Understanding COG is crucial for safe navigation and route planning, as it provides a real-time understanding of where the vessel is in relation to navigational aids or hazards. This information is actively used in electronic navigation systems to ensure vessels stay on course while adjusting for any environmental influences they might encounter.