🔍 Key Concepts

• Transverse thrust (paddle‑wheel effect) of a single screw in reverse • How pressure differences are created around a rotating propeller • The difference between forces caused by the propeller itself vs. forces caused by the rudder

💭 Think About

• Ask yourself: Is the side force mainly created by what happens directly on the propeller blades, or by the water flow after it leaves the propeller? • Which option best describes a force created by unequal pressure on different sides of the propeller disk, rather than by flow hitting another surface? • Does the rudder need to be involved at all for this sidewise force to exist?

✅ Before You Answer

• Identify which choices clearly involve the rudder or wake rather than the propeller’s own action. • Look for the option that directly describes uneven pressure on one side of the propeller vs. the other. • Verify that the cause you pick would still exist even if the rudder were hard over, amidships, or even missing. The correct cause should not depend on rudder position.