Which is the highest priority for COG sensing if GPS is available?

• A. NAVSSI
• B. GPS
• C. WSN-7
• D. DFGMC

Answer: (B)

When GPS is available, use GPS as the source for COG because it provides the actual track over ground directly. GPS measures your position over time relative to the ground, so the change in position yields your true direction of travel, independent of how the hull is oriented or how the current or leeway is pushing the vessel.

Other options aren’t primarily about the actual course over ground. A heading-based sensor like a magnetic compass tells you where the bow is pointing, not where the ship is moving; an INS/NAVSSI setup can infer COG but suffers from drift over time and isn’t as directly tied to ground truth; a wind sensor provides weather data and isn’t used for determining COG. Therefore, GPS gives the most accurate, reliable COG when it’s available.