Which component supports the weight of the main propulsion shaft inside the ship's hull?

The correct answer is the line shaft bearing, as it plays a critical role in supporting the weight of the main propulsion shaft inside the ship's hull. Line shaft bearings are installed along the length of the shaft to reduce friction and provide support, ensuring that the shaft remains properly aligned and stable while the vessel is in operation. This alignment is crucial for efficient transmission of power from the engine to the propeller.

The propeller shaft transmits rotational power but does not directly support its weight within the hull. The stern tube houses the shaft at the aft end and provides a sealing mechanism for the propulsion system but is not responsible for supporting the shaft's weight. The thrust block is involved in transferring thrust from the propeller shaft to the ship's structure but does not serve the function of supporting the weight of the shaft inside the hull. Therefore, the line shaft bearing is the component specifically designed to support the main propulsion shaft effectively.