Question 63 1AE01 - First Assistant Engineer

The Correct Answer is D 1. **Why option D ("Stern tube shaft") is correct:** The component described is the section of the main propulsion shafting that passes through the stern frame (the hull penetration) and connects to the rest of the line shafting inside the vessel, typically ending near the closest watertight bulkhead. This penetration houses the **stern tube**, which is a watertight assembly containing bearings and seals (like the aft stuffing box or stern gland). The section of the shaft that runs within the stern tube and connects the tail/propeller shaft (which is outside, supported by the strut) to the line shaft (which is inside) is specifically called the **stern tube shaft**. 2. **Why the other options are incorrect:** * **A) Tail or propeller shaft:** This is the outermost section of the shafting, which the propeller mounts onto. In an arrangement requiring a strut, the tail shaft extends from the stern tube aft to the propeller, with its aft end supported by the strut bearing. While it is connected to the stern tube shaft, the section *passing through* the hull penetration and ending at the bulkhead is the stern tube shaft itself. * **B) Line shaft:** The line shaft (or intermediate shaft) refers to the long sections of shafting located inside the hull, running between the thrust shaft and the stern tube shaft. It carries power over the length of the ship but does not pass through the main hull penetration (the stern tube). * **C) Thrust shaft:** The thrust shaft is the component that transmits the axial forward or backward force (thrust) generated by the propeller to the ship's structure (via the thrust block/bearing). It is located inside the engine room, typically connected directly to the reduction gear/engine and the line shaft, and is not the section that passes through the stern tube.