Question 60 1AE01 - First Assistant Engineer

The Correct Answer is A **Explanation for Option A (Correct):** Option A correctly identifies the fundamental structural and functional difference related to the power source location. * **Azimuthing Thruster (Z-drive or L-drive):** This system uses mechanical transmission (gears, shafts, or sometimes hydraulics) to transfer power from the prime mover (typically a diesel engine or electric motor) located **inside the ship's hull** down to the propeller unit mounted below. The ability to rotate 360 degrees (azimuth) is achieved by rotating the entire lower gear housing, which is driven by the internal prime mover. * **Podded Propulsor (Azipod, SSP, etc.):** This is an electrically driven system. The prime mover—the main electric motor that turns the propeller—is located **outside the hull** within a streamlined enclosure (the pod) submerged in the water. The electricity needed to power this motor is generated inside the ship's hull and transmitted to the pod via cables, eliminating the need for complex mechanical transmission shafts that penetrate the hull. This placement of the motor outside the hull is the defining feature of a podded propulsor. **Explanation for Incorrect Options:** * **Option B (Incorrect):** This statement is factually wrong for both technologies. Both azimuthing thrusters (Z-drives) and podded propulsors (Azipods) are defined by their ability to rotate 360 degrees (azimuth), meaning **both** are steerable. * **Option C (Incorrect):** This is the direct inverse of the correct statement (A). It incorrectly places the prime mover outside the hull for an azimuthing thruster and inside the hull for a podded propulsor. * **Option D (Incorrect):** Similar to Option B, this statement is factually wrong. Both azimuthing thrusters and podded propulsors are fully steerable, defining their primary function as main propulsion and steering units.