SOG stands for

• A. Speed Over Ground
• B. Speed Through Water
• C. Surface Of Ground
• D. System Of Guidance

Answer: (A)

In navigation, Speed Over Ground is the vessel’s speed relative to the Earth's surface. It’s the actual progress over ground, which you’d see on GPS or on the track line, and it’s what matters for estimating arrival times and plotting a course over a fixed path.

This speed can be different from speed through the water, which is how fast the hull is moving through the water itself. Currents or winds can push you along or against you, changing your SOG without changing your speed through the water. For example, if your speed through water is 12 knots and a current adds 3 knots in the same direction, your SOG becomes 15 knots; if the current is opposite, your SOG would be 9 knots.

Therefore, the correct interpretation is Speed Over Ground. The other options describe different concepts or aren’t relevant terms in this context.