Boat Propeller Shaft Diagram — _hot_

Misalignment is the #1 cause of shaft failure. Your diagram shows bolted flanges, but :

The transmission output flange is a heavy, circular steel disc with bolt holes. The propeller shaft begins with its own (sometimes called a "shaft coupling"). These two flanges are bolted together, often with a flexible coupling in between to absorb minor misalignments. boat propeller shaft diagram

This connects the engine or transmission to the shaft. It must be perfectly aligned to prevent vibrations that can shake your boat apart over time. Misalignment is the #1 cause of shaft failure

At the hull penetration point, usually in the engine room bilge. Diagram Role: The watertight transition. boat propeller shaft diagram