A new rudder system, designed at the University of Strathclyde, and claimed to be greener and more efficient than conventional rudders, is to be retrofitted to a commercial vessel as part of a €6 million EU-funded research project.
The so-called GATERS project, led by the Scottish university, focusses on a U-shaped “gate rudder” which, unlike a traditional rudder that sits behind a ship’s propellers to steer the vessel, sits astride the propeller. As a result, the system, essentially two separate rudders that are joined together, acts like a nozzle around the propeller and generates additional thrust. Both rudders can be independently controlled to provide improved steering as well as helping vessels move sideways when docking, for example.
In early trials, the gate rudder has shown a “remarkable” fuel-saving potential of 15% in calm waters, rising to 30% in rough seas, while also offering improved manoeuvrability. The gate rudder is additionally said to be quieter than a traditional rudder system, reduces hull wake and can help to protect the propeller from damage. The latter feature is said to be particularly beneficial in sensitive environments such as the Arctic.
Professor Mehmet Atlar, who is the project coordinator from Department of Naval Architecture and Marine Engineering (NAOME) at Strathclyde, says: "GATERS demonstrates significantly reduced emissions from ships, particularly within coastal and port areas, challenging and even exceeding the current and future legislative requirements of the International Marine Organization and local regulations for emissions. As a propulsor-based solution, the gate rudder offers a significant amount of power saving that cannot be achieved by any other single energy-saving device which is currently available in the market.”
A further important advantage of the gate rudder system is the high level of manoeuvrability it offers within coastal and port areas as well as an ability to navigate more efficiently in waves during oceangoing operations. Atlar adds: “Furthermore, the gate rudder system is simple, generic and flexible and can be installed on newbuild ships or retrofitted to existing ships, as well as integrated easily with other fuel- saving and emission reduction technologies. Based on these features, the gate rudder design presents a great prospect for replacing conventional designs.”
A target ship for the retrofit has been identified, the 2010-built general cargo ship MV Erge, which is owned by Capa Shipping and Trading, one of the 18 project partners. It is proposed to carry out full-scale trials and voyage monitoring of the ship before and after the gate rudder system has been retrofitted to assess the benefits of this device in terms of powering, manoeuvring, emissions, hull pressure, and vibration underwater radiated noise.
For this purpose, comprehensive inspections and preparations have been underway to equip the 90m-long Erge with special monitoring equipment in July and to start collecting full-scale performance data in August 2021. In the meantime, system model testing has started at the Istanbul Technical University, another partner in the project.
The GATERS patent holder is Dr Noriyuki Sasaki, who is a Visiting Professor in NAOME. The university has also confirmed that concept of the gate rudder has been licenced to the world’s largest propulsion system manufacturer, Wärtsilä.