Thordon Bearings and Wärtsilä have announced the formation of the Blue Ocean Alliance to develop and promote a stern tube-less ship concept.

The Blue Ocean Alliance brings together Thordon Bearings, Wärtsilä, the School of Naval Architecture & Marine Engineering of the National Technical University of Athens (NTUA), naval architect SDARI (Shanghai Merchant Ship Design & Research Institute CSSC) and ABS.

The companies say that the concept of a ship design that does not require a stern tube and eliminates the need for oil-lubricated stern tube seals and bearings is likely to save ship owners hundreds of thousands of dollars in capital and operational expenditure over a vessel’s lifespan, including zero requirement for lubricating oil or biodegradable lubricants.

ABS has estimated that in a stern tube-less ship design, a two-week dry-dock re-alignment or bearing and seal replacement job, can instead be completed in a single day while the vessel is afloat.

Ship designer SDARI, in partnership with Thordon and NTUA, has already been granted an Approval in Principle (AIP) from ABS for the concept design of the stern tube-less vessel with Thordon’s COMPAC Split Seawater-Lubricated Aft Bearing. ABS is further developing a pertinent Guide and Notation for such a ship.

Thordon is calling the concept T-BOSS (Thordon-Blue Ocean Stern Space). The vessel’s stern tube cooling tank is replaced with a dry irregularly shaped chamber, thus allowing for inspection and maintenance of a seawater-lubricated single bearing and seal from inside the ship, while afloat, without any need to withdraw the shaft.

The T-BOSS utilizes Thordon’s seawater-lubricated COMPAC propeller shaft bearing system and the Wärtsilä Enviroguard Seal, which requires no maintenance between planned overhauls of up to five years. As well as eliminating the need to withdraw the propeller shaft for the lifetime of the ship, the COMPAC bearing comes with a lifetime bearing wear life guarantee.