The QM2's Secret: Why The World's Only Ocean Liner Carries Spare Propellers on Deck

Visible right on the bow of QM2's Deck 7, the spare propeller blades look like an unusual piece of art; they are often referred to as the "Captain's Cufflinks." However, they are far more than just decoration; they are vital, custom-designed pieces of equipment.In this video, we dive into the engineering reason why the QM2, which often sails to distant ports, chooses to carry spares right there with her, just like having a spare tyre for your car. We'll explore the complex world of cavitation, the process where air bubbles form on the propeller and implode, which can cause significant damage and vibration. Discover why every large ship's propeller is uniquely designed for its specific hull and powerplant, and why an off-the-shelf replacement is not an option. We'll look at historic examples, including the refits of ships like the QE2, where propeller design was changed during a ship's career to combat issues like vibration.You'll find out the real, technical reason why these spares are kept aboard, ensuring the ship can continue its journey, regardless of where the vessel is in the world. Learn More About Cavitation:Casual Navigation has a fantastic video explaining exactly how cavitation works. I've linked it here: https://www.youtube.com/watch?v=2cnKzCTJC_8 If you can think of other passenger ships where the spare propeller blades are carried in plain view, please let me know in the comments below! — 🚢 My History Website: https://www.chriscunard.com/ 📚 Buy my books: https://www.chrisframe.com.au/books 👕 Buy cruise merch: https://themaritimehistorian.teemill.com/ 🎶 Check out my Substack: https://themaritimehistorian.substack.com/ 🛳️ Learn more about cruising at my Blog: https://www.chrisframe.com.au/ — QM2’s spare propeller blades are stored in a passenger area, at the forward end of Deck 7. They are sometimes referred to as ‘the Captain’s cufflinks’ and look like they could be an art piece. But they are actually functional and necessary pieces of equipment. Carrying spare propeller blades with the ship is a little like having a spare tyre for your car. If something happens to your tyre, you are able to swap the tyre out and hopefully continue on your journey. For QM2, which often travels to distant ports, it makes sense to carry a few spares. Especially since the ship’s propellers are custom designed. If a blade falls off or gets damaged, the spares are able to be fitted to the ship and the ship can continue on its way. When the ship is far from the shipyards where the usual maintenance is undertaken, it is far easier to have the spares already with the ship, than to have to send them to the ship. Cavitation can also cause damage to the propeller blades themselves, further increasing the level of vibrations. To counter these effects, the propeller blades for a ship have to be designed in such a way as to limit both vibration of the ship from the movement of the blades and cavitation. And for that reason, the blades are custom designed for the ship they are going to be used on. QM2 isn’t the only ship to carry spare propeller blades. If you can think of another passenger ship where the spare blades are carried in plain view, then please let me know in the comments. — Tags: #qm2 #queenmary2 #cunard #cunardline #shipbuilding #cruiseship #oceanliner — Imagery References: • Norwegian Sky / Norwegian Sun: NCL Media Kit • Silver Wind: Silversea Media Kit • Various contributors via Unsplash: -- Propeller by Darren Halstead: https://unsplash.com/photos/VAFwHaR8YA4 -- Car Tyre by Chinmay Jade: https://unsplash.com/photos/XNN9C8MG4KM -- Changing Tyre by Marc Kleen: https://unsplash.com/photos/GeeZAavtFy4 • QM2 drone footage all shot by Luke Morrison who obtained approval for a flight path near the ship. • Cavitation Damage / Erik Axdahl / CC BY SA 2.5 Generic / https://tinyurl.com/http0009 • QE2 in Bremerhaven / Dashers / CC BY SA 3.0 / https://tinyurl.com/httpqe2 • Lusitania alongside NYC / Library of Congress / Public Domain / https://tinyurl.com/http1907 • Cavitating Propeller / Public Domain / https://tinyurl.com/http9989