🔍 Key Concepts

• Electronic Plotting Aid (EPA) is used to automatically track another vessel and predict its movement • Think about which input is essential for calculating Closest Point of Approach (CPA) and Time to CPA (TCPA) • Consider what information a plotting aid would need continuously to update a target's future position

💭 Think About

• Which of the choices is a quantity that directly affects how quickly a vessel’s position changes over time? • If an EPA is predicting where a vessel will be, what basic motion information must it receive as an input? • Which of these pieces of information is most critical to motion prediction: where you are now, how fast you’re moving, how deep the water is, or what direction you’re pointed relative to something else?

✅ Before You Answer

• Identify which option is directly related to rate of movement rather than just current state (like position or depth) • Ask: which value must be known accurately and continuously for plotting future positions on a display? • Eliminate any options that are not fundamental inputs to standard radar/EPA tracking and CPA/TCPA calculations