By involving propulsion manufacturers early in the design process, naval architects can design ships to be more efficient
Propulsion suppliers can design propulsion solutions from engine to wake to minimise operating costs and emissions without impacting vessel safety.
This was one of the key conclusions from a panel of technical experts at Riviera’s Propulsion packages: the full package? Propulsion packages critically assessed webinar. This event, sponsored by Berg Propulsion, was held on 26 February 2021 during Riviera’s Marine Propulsion Webinar Week.
It brought together propulsion manufacturers with an end user to demonstrate how technology can be developed and implemented to improve vessel efficiencies.
On the panel were Berg Propulsion product director Emil Cerdier, Veth Propulsion product manager for thrusters Bastiaan van Zuijlekom, Servogear managing director Torleif Stokke and Saga Cruises captain Kim Tanner.
They discussed how efficiency is a complex interplay between vessel and propulsion train design and operation.
Mr Cerdier said vessel efficiency involves all elements of propulsion, hullforms and operations. “To reach efficient operations, the key is to look at all aspects,” he said.
“Companies should look at the interaction and operations for more efficient ways.”
Naval architects and shipyards should co-operate with propulsion package providers to produce efficient newbuilds with new technologies such as hybrid propulsion, electric-driven thrusters or engines burning alternative fuels.
“They should take advantage of the technology solutions,” said Mr Cerdier. He highlighted how Berg Propulsion had redeveloped the nozzle on one of its azimuth thrusters to improve efficiency. We studied the nozzle attachment system on our second-generation thruster and came up with improvements for generation three,” he said. “These improvements led to an increased efficiency that means you reach 3% higher bollard pull with the same input power, or need 5% less power to reach the same bollard pull.”
Mr van Zuijlekom emphasised the benefits for vessel efficiency when involving propulsion manufacturers and integrators during ship design. “We should be getting involved at the early stage in design and construction and finding out what customers and designers want,” he said. “We can provide flexible and efficient co-operation for system integration.”
Naval architects can use their knowledge and technology to provide more space on vessels for cargo and passengers, or they can use propulsion technology to design shallow-draught vessels.
Mr Stokke commented on developments in electric-driven propulsion for high-speed vessels, such as fast ferries with hybrid propulsion, or driven by batteries. “We are looking into what is possible from using electric-power instead of conventional diesel in variable power ranges,” he said.
What is important in electric-vessel design is the integrated propulsion. “An electric engine in combination with a gearbox gives reduced weight and reduced capital expenditure,” said Mr Stokke. He said it is more cost-effective to improve the efficiency of the propulsion package than invest in batteries with more storage capabilities. “We can help with efficient solutions,” he said.
Captain Tanner spoke about advantages and disadvantages of podded azimuth propulsion from a user perspective. He is a master on Saga Cruises newbuild cruise ships Spirit of Discovery and Spirit of Adventure. These have podded propulsors able to rotate 360° for manoeuvring and docking. “They provide more lateral movement for moving vessels alongside or getting into smaller ports,” said Capt Tanner.
Podded propulsion is also better for environmental aspects of cruise shipping. “Pods create less noise and vibration, which equals less impact on sea life,” he said.
There are also lower emissions as fewer generators are required for electric propulsion than using main engines and conventional propellers.
Attendees of the webinar were asked a series of question on propulsion packages. They were asked what they thought would be the most important factor in reducing fuel consumption. Of those who replied, 68% thought it would be system efficiency – the best combination of equipment based on the specific operation. Another 28% said it would be operational efficiency – how the vessel is being operated by the crew. But only 4% thought product efficiency – individual devices optimised for the highest possible efficiency was the most important.
In another poll, 45% agreed simplicity of equipment is more important than maximum efficiency, but 55% disagreed.
There were high levels of agreement from attendees that propulsion system manufacturers should always be involved in ship design with 56% of respondents strongly agreeing, 33% agreeing, just 7% had no strong feelings either way and 4% disagreed.
Attendees were then asked their thoughts on whether shipowners should be able to choose their preferred suppliers for key equipment such as propulsion for a newbuild. Half of the respondents voted Yes, this way operational costs are also considered. Another 29% said Yes, operational costs should always be more important compared to initial costs. Then another 16% voted for Yes, that is why owners should buy their own equipment, 3% thought No, this will undermine the position of the builder and 2% thought No, the builder will make the optimal choice anyway.
In another poll, attendees were asked their opinion on whether shipbuilders should consider operational costs more compared with the initial cost of equipment. Around 41% strongly agreed, 38% agreed, 10% disagreed and 11% had no feelings on the question.
Attendees were also asked what they thought was an acceptable payback time for a higher initial investment [in propulsion] with a lower lifecycle cost. About 30% thought it would be 0-5 years, 56% thought 5-10 years and 14% more than 10 years.
Finally, attendees were asked where their company was on its zero-emissions journey. Around 28% said they were well underway with plans for the next five years, 21% said their companies were getting underway and 9% thought there were plans for the next 10 years. But 24% said zero emissions was not on their radar and 18% thought they would deal with Covid-19 coronavirus pandemic first.
Riviera’s Propulsion packages: the full package? Propulsion packages critically assessed webinar panel were (left to right): Servogear managing director Torleif Stokke, Saga Cruises captain Kim Tanner, Berg Propulsion product director Emil Cerdier and Veth Propulsion product manager for thrusters Bastiaan van Zuijlekom
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