Technology group Wartsila has designed and delivered controllable pitch propellers for Stena’s new Ro-Pax vessel, Ala’suinu, which has successfully completed sea trials. Following these sea trials, Ala’suinu became the first Ro-Pax vessel to fulfil the DNV Silent(E) notation, satisfying the criteria in the operating conditions at 11 and 18 knots. This environment class notation from DNV was introduced to protect sensitive marine ecosystems, applying to vessels that demonstrate the ability to effectively reduce emissions of underwater radiated noise.
The Ala’suinu, which was built at CMJL Shipyard (Weihai) in China, is under a 5-year lease to Marine Atlantic, a Canadian operator based in province of Newfoundland & Labrador. Environmental sustainability was a prime consideration in the design of the 203 metres-long ship, which will sail between Nova Scotia and the island of Newfoundland from June 2024.
During the design process of the controllable pitch propeller, Wartsila’s industry-leading in-house design experts paid special attention to underwater radiated noise as a key design parameter. This was done without compromising on other important propeller design requirements, such as ensuring optimal performance and efficiency, for example. As well as reducing emissions of underwater radiated noise, Wartsila’s propeller ensures that owners and operators gain the benefits of lower operating costs and a reduced environmental footprint through less fuel consumption and fewer exhaust emissions.
In addition to the dedicated propeller, Wartsila has also supplied an integrated hybrid propulsion system for this vessel, consisting of Wartsila 46DF main engines, Wartsila 20DF auxiliary engines, both of which are complimented with Wartsila NOx Exhaust gas cleaning system and Wartsila LNGPac, as well as the reduction gear boxes and bow thrusters with motors. Also included in the scope are the Hybrid DC-link Shaft Generator system, Batteries and Energy & Power Management System, Integrated Automation System and Navigation & External Communication System.