Is A Water-Lubricated Propeller Shaft Arrangement More Efficient Than Podded Propulsion?

A Thordon Bearings White Paper
 
In the twenty-five years since the first podded propulsion system was introduced to optimise the ice-breaking performance and manoeuvrability of ice-breakers operating in the far North, the pod has now more than 400 installations on various ship types, including super-yachts, high-speed ferries, oil tankers and offshore vessels and rigs.
 
It is the cruiseship, however, that provides the pod manufacturers with their greatest market share with over 60% of today’s newbuild cruiseships specified with podded propulsion. High manoeuvring capability, low noise and vibration and space-saving characteristics of a podded propulsion system are key benefits claimed by the pod manufacturers.
 
Yet while there is a significant number of cruise vessels specifying the pod, there are as many cruiseships opting for more traditional seawater-lubricated propeller shaft lines. To date, there are over 30 cruiseships operating with seawater-lubricated propeller shafts. Current seawater-lubricated propeller shaft line orders from Princess, P&O, MSC, Regent Seven Seas, Viking, Seabourn and Oceania show that many operators continue to favour this traditional approach to propulsion, largely because the conventional shafted system is still widely seen as the more cost-effective option with proven reliability, performance and environmental efficiencies.
 
The aim of this White Paper is to consider both propulsion arrangements in order to stimulate interest for further comparative studies into their performance, cost efficiency, operational and safety characteristics, and to provide shipowners with a better understanding of the two very different arrangements in order to make more informed procurement decisions.