🔍 Key Concepts

• Doppler sonar log measures speed through water using sound waves and the Doppler effect • How hull attitude and motion (roll and pitch) affect the direction of the sonar beams • How draft and vibration might change the geometry, angle, or clarity of the sonar signal

💭 Think About

• Which of these options would change the angle or direction of the sonar beams relative to the water? • Which factor mainly changes how the ship sits in the water (depth) but not the pointing direction of the transducers? • Which effect is most likely to cause signal noise or intermittent readings rather than a steady geometrical error?

✅ Before You Answer

• Identify which motions of the vessel (roll, pitch) alter the orientation of the transducer with respect to the water flow • Consider whether increased draft changes beam direction or mainly distance from the keel to the water surface • Think about which condition would cause mechanical/structural vibration that could disturb the sonar equipment or its readings