Shipbuilding industry is awesome. Marcin Ryngwelski on the propeller shaft - how engine power reaches the propeller

The propeller shaft is one of the most crucial components in a vessel’s propulsion system. It is the link that transfers the engine’s torque to the propeller, setting the ship in motion. - The propeller shaft is essentially the backbone of the propulsion train. It must be perfectly straight, perfectly aligned, and properly maintained to ensure safe and efficient operation of the vessel, explains Marcin Ryngwelski, CEO of PGZ Naval Shipyard.

Kamil Kusier executive editor 11.09.2025, 17:18 Reading time: 2 min

Stern of a vessel on dock supports showing a red propeller shaft and steering tunnel — fot. Marcin Ryngwelski / PGZ Stocznia Wojenna

In brief

A propeller shaft transmits power from the main engine to the propeller and in large vessels can reach several dozen metres in length. Marcin Ryngwelski, president of PGZ Stocznia Wojenna, compared the propeller shaft to the backbone of the propulsion system and noted that an axis deviation of fractions of a millimetre causes vibration, noise and accelerated bearing wear. Installation is carried out with laser alignment systems, and sections are joined with flanges and high-strength bolts. During docking the shaft is sometimes removed in its entirety for inspection, and temperature and vibration sensors are increasingly used.

Precision engineering – down to the millimeter

A propeller shaft is a massive, high-strength steel component that can reach dozens of meters in length on large vessels. Its installation is one of the most demanding stages of ship construction or overhaul.

- Every millimeter counts. Even the slightest misalignment can lead to vibrations, noise, and, in the long term, accelerated wear of bearings and other propulsion components, says Marcin Ryngwelski.

For this reason, installation is carried out with the help of advanced alignment tools, including laser measurement systems. The shaft is typically assembled from multiple sections joined with precision flanges and high-tensile bolts.

Maintenance – key to reliability

During dry-docking, the entire propeller shaft is often removed for inspection, bearing replacement, and seal servicing.

- Neglecting shaft maintenance is a direct risk to the ship’s operational availability and can result in costly failures. Our engineers put a strong emphasis on scheduled inspections and diagnostics, notes Marcin Ryngwelski.

Modern systems increasingly include condition monitoring sensors that continuously track shaft temperature and vibration levels. The collected data allows early detection of anomalies – preventing damage before it occurs.

An invisible but critical component

As Ryngwelski stresses, the propeller shaft may not be visible to the crew or passengers, but it is a key contributor to both safety and efficiency at sea.