In a ship design initiative to protect oceans from pollution, Thordon Bearings and Wärtsilä have formed the Blue Ocean Alliance to develop and promote sterntubeless ship concept.
The Blue Ocean Alliance brings together maritime industry expertise, with seawater-lubricated bearings company Thordon Bearings, systems integrator Wärtsilä, the school of naval architecture and marine engineering of National Technical University of Athens (NTUA), naval architect Shanghai Merchant Ship Design and Research Institute (SDARI) and classification society, ABS, who championed the initiative in 2019. Thordon and its partners are said to strive to decarbonise the marine and energy sectors.
The concept of a ship design that does not require a sterntube and eliminates the need for oil-lubricated sterntube seals and bearings is said to be revolutionary. The design is likely to save ship owners US$100,000 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 sterntubeless ship design, a two-week dry-dock realignment 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 sterntubeless vessel with Thordon COMPAC split seawater-lubricated aft bearing. ABS is further developing a pertinent guide and notation for such a ship.
Thordon is calling the concept Thordon-Blue Ocean Stern Space (T-BOSS), a sterntube-less propeller shaft system design, in which the vessel’s sterntube 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 utilises Thordon’s award-winning seawater-lubricated COMPAC propeller shaft bearing system and the Wärtsilä Enviroguard seal, which reportedly requires no maintenance between planned overhauls of up to 5 years. It also eliminates the need to withdraw the propeller shaft for the lifetime of the ship, the COMPAC bearing comes with a lifetime bearing wear life guarantee.
Thordon Bearings CEO Galoni said, “The Blue Ocean Alliance brings a partnership to develop the concept. Several ship owners have already shown interest in this solution is extremely encouraging.
“The T-BOSS concept introduces a new approach to a merchant vessel’s aft layout — removing the sterntube casing — employing seawater for lubrication and creating a dry chamber to permit in-water maintenance for the first time. These innovations enable ship owners and shipyards to eliminate propeller shaft oil emissions, simplify maintenance and lower operational costs.”