All new ships to be built without a sterntube?


Future newbuild ships of all types should be built without a sterntube and with a seawater-lubricated propeller shaft bearing arrangement, according to Blue Ocean Alliance’s Chris Leontopoulos.


Speaking at a recent maritime industry forum in Hamburg, Mr Leontopoulos said the sterntubeless ship design – jointly developed by Blue Ocean Alliance members ABS, Thordon Bearings, Shanghai Merchant Ship Design and Research Institute (SDARI), Wärtsilä, and the National Technical University of Athens (NTUA) – is so commercially, operationally and environmentally attractive that “I personally hope that in the future all ships are built like this”.


Kick-starting his presentation with the startling statistic that more than eight million litres of sterntube lubricating oil is polluting the oceans annually, Mr Leontopoulos, ABS’ Vice President, Technology, EMEA, said the design interventions proposed by the group can deliver a commercially and environmentally optimal vessel capable of saving hundreds of thousands of dollars in operational costs. This, without changing hull lines or existing class rules and regulations.


“We decided to remove the sterntube, and by shortening propeller shaft length and moving the prime mover further aft, we no longer needed a forward sterntube bearing. This places less friction on the shaft, resulting in lower power loss, improved fuel efficiency and reduced emissions. A sterntubeless ship also results in a bigger cargo space for the same vessel length,” he said.


Mr Leontopoulos went on to say that the use of a seawater-lubricated bearing with a tapered key design – the principal component that makes the sterntubeless ship possible – also removes the need for an aft seal and a shaft coating system. The sterntubeless design features a seawater-lubricated bearing, a Wärtsilä forward shaft seal, a Water Quality Package and a bulkhead seal. The technical differences were immediately obvious when a graphic was shown comparing a ship with and without a sterntube. Essentially, the design presents a dry internal inspection chamber aft of the engine room, in the


108 | ISSUE 109 | SEP 2024 | THE REPORT


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