Which of the following components acts as the last support device for shafts before the propeller?

The correct response is that the strut bearing serves as the last support device for shafts before the propeller. Strut bearings are critical components positioned near the transom of a vessel, where they provide essential support and stability to the shaft as it extends toward the propeller. They are designed to handle radial loads and minimize vibrations during operation, which is crucial for maintaining alignment and efficiency in the propulsion system.

The strut bearing also plays a vital role in reducing friction between the shaft and the bearing surface, ensuring smooth rotation and longevity of the components. This support is particularly important because it bears the weight of the propeller shaft and contributes to the overall reliability of the propulsion system.

Other components mentioned, such as line shaft bearings and shaft seals, serve important functions but are not positioned as the final support before the propeller. Line shaft bearings typically support the shaft section that extends between the engine and the strut bearing, while shaft seals are employed to prevent water from entering the hull and to maintain lubrication for the shaft. An air receiver flask is unrelated to shaft support and is part of pneumatic systems used for compressing air. Therefore, the strut bearing is uniquely positioned to provide crucial last support right before the propeller, making it the correct choice