Manoeuvring: lowering emissions and fuel consumption

Green solutions and cutting fuel consumption are among the major trends when it comes to manoeuvring solutions for passenger ships.

One of the latest developments in the passenger vessel segment is the Schottel Rudder EcoPeller (SRE), covering the power range from 500 to 3,500 kW. Schottel sales director, cruise, ferry and yachts Andreas Witschel says “With its hydrodynamically optimised design the SRE generates maximum steering forces in combination with the smallest possible steering angles, enabling top performance in terms of overall efficiency and course stability. This reduces fuel consumption and ensures lower operating costs and emissions.”

Maximum mechanical capability is also assured as the SRE is designed as an L-drive. This means it does not have an upper gearbox inside the vessel, which would reduce efficiency. “Instead of the upper gearbox, highly efficient and compact permanent electric motors will be installed on top of the thrusters. By featuring the L-design principle, low noise and vibration levels ensure the highest onboard comfort,” says Mr Witschel.

With medium-sized azimuth thrusters, Schottel meets new challenges in the international maritime market. These include shifted engine power classes, new ice-class rules and the growing trend towards electric or hybrid-drive vessels. Combining the latest technologies in mechanical engineering, hydrodynamics and digitalisation, the medium-sized thrusters are available in sizes corresponding to the new engine power classes: SRE 210 (560 kW) and SRE 270 (900 kW). Schottel also offers an L-drive variant of the EcoPeller type SRE 150 (300 kW).

Since its market launch in 2016, more than 30 Schottel Rudder EcoPellers have been in operation – mainly in ferries. Among them is the world’s first hydrogen ferry for Norwegian ferry operator Norled. “By providing sustainable propulsion solutions, Schottel is able to support operators on their way towards a greener future and to help them to comply with emissions and environmental regulations,” comments Mr Witschel.

Beyond this, Schottel has been awarded contracts in the Canadian ferry market, including for BC Ferries and Seaspan. These vessels will be equipped with battery-electric, hybrid propulsion systems driven by Schottel twin propellers (STP). “STPs are the ideal alternatives for quiet vessels or applications with limited installation space, draught or propeller clearance. By sharing the load between two propellers, the risk of cavitation is minimised and tip clearance is increased. These characteristics lead to lower underwater radiated noise and vibration levels. This concept also improves the efficiency of the propulsion system and reduces fuel consumption compared to single propeller systems,” says Mr Witschel.

In Norwegian ferry projects, an increasing number of autocrossing or automooring systems are being installed. With EcoVoy already in operation on a ferry route, Schottel offers not only suitable interfaces, but also its own autocrossing system.

By implementing state-of-the-art technologies, such as computational fluid dynamics (CFD), Mr Witschel says Schottel develops and optimises propulsion systems in the most modern way. CFD calculations can be used to simulate and analyse a wide range of applications, for example, open-water propeller performance, vessel resistance and towing power, manoeuvrability, risk of cavitation or noise development.

Mr Witschel says “Latest methods such as CFD are essential to develop and continuously improve propulsion systems. By this, the positive impacts of the effective fin and greater propeller diameter have been investigated to ensure high steering forces, high efficiency and high manoeuvrability.”

Manoeuvring for battery ferries

Recent notable deliveries include Brunvoll supplying the hybrid propulsion package for battery-hybrid ferry Color Hybrid. This included gearboxes, controllable pitch propellers, tunnel thrusters, rudders, steering gears and control systems.

“This is a ground-breaking contract for Brunvoll,” said Brunvoll Volda chief executive Hallvard Pettersen when the contract was announced. “It is the first complete equipment package supplied by Brunvoll, Brunvoll Volda and Brunvoll Mar-El together. It is a great honour to be chosen as supplier to this vessel, which has also been awarded the ‘Next Generation Ship’ prize at Nor-Shipping.”

The propulsion configuration is designed for a combination of diesel-mechanical, electric or battery operation modes. The rudder has been integrated with the propeller and hull to achieve optimum fuel efficiency.

The thruster package consists of two fixed-pitch propeller tunnel thrusters and one rim-driven, permanent magnet-powered tunnel thruster. Delivery also includes control systems for propulsion, positioning and manoeuvring.

Ulstein Fosen Design and Engineering manager Per Edvin Tande comments that this is a “highly flexible plant that has several available modes”.

He adds “The owner requested diesel-mechanical peak shaving and we have stabilised conditions for the main engines, which are operating between 20 to 25%, so using 60% battery capacity.”

MSC World-class

The technology group Wärtsilä will supply Chantiers de l’Atlantique, France, a comprehensive package of integrated solutions designed to support and enhance the efficiency and environmental sustainability of the first two World-class cruise vessels being built for Geneva, Switzerland-based MSC Cruises.

The ships will operate on clean-burning LNG fuel, with optimal environmental performance. The orders with Wärtsilä were placed by Chantiers de l’Atlantique in Q3 2018 and Q1 2019. These will be the first two cruise ships to run on LNG with Wärtsilä 46DF engines, and with Wärtsilä LNGPac systems.

The cruise industry’s profile is now very much geared towards sustainable operations. Wärtsilä’s Smart Marine vision, whereby high levels of digitalisation and connectivity are used to deliver greater efficiencies and better environmental performance, strongly supports this trend.

“The focus of our solutions is on reducing energy and fuel consumption to promote efficiency. At the same time, our nitrogen oxide reduction and LNG solutions enhance environmental sustainability, which together with the higher efficiency, is very much in line with Wärtsilä’s Smart Marine strategy,” says Wärtsilä Marine Power Solutions vice president Stefan Nysjö.

“We are very familiar with Wärtsilä’s products and they have always provided us with excellent support in newbuild projects. These two new cruise ships will represent the latest thinking in minimising the environmental impact and reducing fuel consumption, which is in line with our Ecorizon plan, and Wärtsilä is playing a major role in this,” says Chantiers de l’Atlantique technical director Yves Pelpel.

The full scope of Wärtsilä’s supply of fully integrated solutions includes, for each of the two vessels, five 14-cylinder Wärtsilä 46DF dual-fuel engines fitted with nitrogen oxide reduction (NOR) units, two Wärtsilä LNGPac fuel storage and supply systems, seven Wärtsilä thrusters, and two Wärtsilä fixed pitch propellers. The Wärtsilä 46DF engines are IMO Tier III-compliant in gas mode and are compliant in marine diesel oil mode in combination with the NOR units. The Wärtsilä equipment is scheduled for delivery in mid-2020 for the first ship, and in mid-2022 for the second.