In an initiative which hopes to be transformational for ship design while protecting the oceans from pollution, a new alliance, known as the Blue Ocean Alliance, has been formed to develop and promote a sterntube-less ship concept.
The Blue Ocean Alliance brings together maritime industry expertise, with systems integrator Wärtsilä, seawater-lubricated bearings company Thordon Bearings, 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 classification society ABS, who championed the initiative in 2019.
The concept of a ship design that does not require a sterntube and eliminates the need for oil-lubricated sterntube seals and bearings is considered revolutionary. The design is likely to save ship owners significant sums 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 sterntube-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 remains 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 sterntube-less vessel with Thordon’s Compac Split Seawater-Lubricated Aft Bearing. ABS is further developing a pertinent Guide and Notation for such a ship.
The Thordon concept is known as T-Boss (Thordon-Blue Ocean Stern Space), a novel 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. T-Boss includes 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 guarantee.
Anna Galoni, CEO, Thordon Bearings, said: “The Blue Ocean Alliance brings together a formidable partnership to develop and further promote the concept. The fact that 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.”
Rob Burford, VP Shaft Line Solutions, Wärtsilä, said: “The Blue Ocean Alliance and the sterntube-less ship design promise to revolutionize the way that ships are built and operated, delivering cost savings and efficiency improvements.”
The alliance partners will strive to shape the decarbonisation of the marine and energy sectors, with products and solutions that provide efficiency, reliability, safety and environmental performance.
