🔍 Key Concepts

• apparent wind vs. true wind – how the wind you feel on deck is a combination of real wind and the vessel’s motion • vector subtraction – apparent wind is true wind minus the ship’s motion through the water • conditions for zero apparent wind – when two equal and opposite effects cancel each other

💭 Think About

• Imagine you are standing on deck underway: what has to be true about the real wind and your ship’s motion so that you feel no wind at all? • Think of the true wind as one arrow and the ship’s motion as another arrow: what has to be true about their lengths (speeds) and directions for the result to be zero? • Which option describes something that could be ONE of those two needed conditions, without by itself guaranteeing zero apparent wind?

✅ Before You Answer

• Be sure the choice can be true on a moving ship and still lead to zero apparent wind when combined with the correct direction condition. • Check whether the option talks about speed or direction and ask: is that something that could be just one of the two required conditions? • Eliminate any answer that would make the apparent wind obviously stronger instead of zero when the ship is moving (think about wind from dead ahead).