🔍 Key Concepts

• Relative vs. true wind on a moving vessel • How ship movement affects instrument readings • Which elements depend on the vessel’s motion and which do not

💭 Think About

• Ask yourself: Which of these elements would read the same whether the vessel was stopped or moving? • Think about what a barometer, thermometer, and visibility from the bridge actually measure—are they affected by ship speed and heading? • Consider which weather element is usually reported as relative when measured on board a moving ship.

✅ Before You Answer

• Identify which elements are measured with fixed instruments that are not direction‑sensitive (e.g., barometer, thermometer). • Identify which element depends directly on both the ship’s heading/speed and the air flow direction/speed. • Before choosing, decide whether you are thinking of true conditions or what is observed relative to the moving vessel.