Propeller shafts or in marine terminology also known as tail shafts are commonly found on the ship’s aft segment behind the ship’s propulsion. It is a round metal fixture attached to rotate, connect, and mediates force from one component to another.

The tail shaft is a part of the propulsion system not only in marine but also in automotive and aviation. In general, it serves as a connection between the engine and the drive unit, for boats the drive unit is called the propeller.

A propeller is a fan-like structure situated underwater and attached to the vessel shafts. These propellers have various types and forms but the main principle is to have twisted blades that when rotated cause lateral motion on the plane where it is being spun. This lateral motion is therefore seen as the ship’s movement either ahead or astern.

The connection built by the tail shaft between the main engine and the propeller also transmits the power (speed and torque) produced by the main engine to the ship’s propellers.

Precisely, the energy coming from the main engine whether diesel or electric that is manifested on its flywheel is connected to a marine gearbox (if equipped) or directly to the propeller shafting, depending on if an intermediate shaft is needed or only the propeller shaft is installed.

The energy held into the driving shaft is delivered to the propeller where it translates the rotating motion to the forward and reverse movement of the ship’s hull.

On a broad understanding, the connection between the engine to the shaft and to the propeller acting as a single unit forms a system called propulsion. As you can see, the design varies to fit the vessel conditions for example vessel size and type.

The propulsion system adapts to the vessel’s needs. Manufacturers of such take worth considering the length between the ship engine and the propeller. The longer space between the said components more additional fittings/ parts are installed to ensure the firmness and efficiency of the system.

The length between the engine and propeller differs per vessel type. As we all commonly know the propellers are always fitted on the ship’s rearrest portion but the engine position can either be in the middle or later part of the ship.