You estimate the current at 2.0 mph. What is...

🔍 Key Concepts

• Speed over ground (SOG) is your actual speed across the earth, combining your speed through the water and the current • Relationship: SOG = speed through water ± current (depending on whether current is helping or opposing) • Unit consistency: both vessel speed and current must be in the same units (mph)

💭 Think About

• Is the current in this situation helping your vessel (moving in the same direction) or opposing it (moving in the opposite direction)? • If your vessel’s speed through the water were known, how would you combine it with a 2.0 mph current to get SOG? Add or subtract? • Look at the answer choices: which ones look like they could be a ‘helped’ speed (faster than through the water) and which look like an ‘opposed’ speed (slower than through the water)?

✅ Before You Answer

• Be sure you are thinking about speed over ground, not speed through the water • Confirm whether you should add or subtract the 2.0 mph based on current direction relative to your course • Check that your final SOG is reasonable compared with the vessel’s speed through the water (it should be slightly higher or lower, not a huge change)

You estimate the current at 2.0 mph. What is the speed over the ground?

9.5 mph

5.5 mph

5.0 mph

4.5 mph

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