Gunnerus is 31.25m long and is owned and operated by NTNU, the Norwegian University of Science and Technology based in Trondheim. It is equipped to carry out research in the fields of biology, technology, geology, archeology, oceanography and fisheries, and so supports many of the courses offered by NTNU.
When the ship was conceived the aim was that it should not only be a platform for scientific research, but a tool for the development of innovative marine technology. This secondary role is the one Gunnerus will now undertake, a key part of the thruster development work.
As built, the ship has diesel electric propulsion in a traditional twin screw arrangement. For the new thruster fit, Moen Marine won the contract for the conversion work, with Polarconsult designing the hull modifications to accept the azimuth thruster mountings and feed the propulsion forces into the structure.
The original high speed diesel gensets are retained, and have been fitted with extremely flexible mountings to stop any structural-borne noise potentially affecting research results. As part of the conversion work the propellers, shaftlines rudders and steering gear have been removed, and the sterntubes plugged, but the skeg remains in place.
Two PM azimuth thrusters conservatively rated at 500kW have been fitted to the research vessel Gunnerus
These technology demonstrator PM azimuth thrusters will have a rating of 500kW to match the test vessel’s availalble power, but the propeller diameter is generous for the loading, which means a thruster with the same diameter propeller can handle up to 1,000kW.
Each thruster comprises three main assemblies – the PM motor/propeller/nozzle underwater unit, the hull mounting system which includes the azimuth bearing and duplicate frequency controlled electric steering gear, and the inboard power unit unit which feeds electric power to the thruster.
“Vessel and thrusters are an ideal match,” says Gunnar Johnsen, Head of Electrical Systems Research & Technology. “Because of the research work Gunnerus does, it is well equipped to do many jobs that will benefit for the added manoeuvrability azimuth thruster will confer, it is also designed to be quiet.
The PM motor is built into the nozzle and the propeller has an advanced forward skew blade design. Nozzle shape can be selected to suit individual applications, but since Gunnerus requires pull for towing trawls and other gear, the nozzle is optimised for bollard pull and speed to match the vessels requirements. The installation is compact, with only the slip ring unit and the variable frequency steering motors inside the hull. In other respects the azimuth thruster uses the same technology as the PM tunnel thrusters.
Under a multi-partner agreement Rolls-Royce is the lead partner, with NTNU as shipowner and operator. The project has been awarded funding from MAROFF, the marine arm of Forskningsrådet – the Research Council of Norway.
Other partners are Marintek, DNV, Olympic Shipping and the Technical University in Ålesund. Through its UTC (university technology centre) programme Rolls-Royce already has a longstanding relationship with Marintek and NTNU on marine propulsion and hydrodynamics research, while Olympic Shipping has for several years been linked to the PM tunnel thruster development work through its vessel Olympic Octopus.
For further information please contact:
Head of Electrical Systems Research & Technology - Rolls-Royce
Three vessels, Viking Star and sisters Viking Sea and Viking Sky were ordered from Fincantieri in Italy, to bring in a new area of destination-focused ocean cruising for the company. The Viking vessels are fitted with energy-efficient engines and benefit from a hydrodynamically optimised and streamlined hull together with a twin Promas system for maximum fuel efficiency. Rolls-Royce also integrated the steering gear and supplied the deck machinery.
Viking Star, is a 47,800gt ship, 228.2m long with a beam of 28.8m. It has nine decks and can accommodate 930 passengers in 465 staterooms of different sizes all with their own verandas. Viking has incorporated a number of the popular features from its successful river cruise longship concept in the new design. These include indoor and outdoor dining venues. The top two decks are a bespoke observation area, and a promenade deck right around the ship.
“These innovative cruise vessels presented an interesting design challenge,” said Senior Hydrodynamicist, Robert Gustafsson, “with the focus not only on efficiency and noise, but also manoeuvrability, as the vessels are designed for direct access to most ports for easy and efficient embarkation and debarkation during their cruise itineraries”.
The design challenge was to match the blade design to the hull to maximise propulsive efficiency, yet be exceptionally quiet. The hull designers were aware of the need for excellent inflow to the propellers, as well as good clearance between propeller blade tips and hull, if propeller induced noise was to be minimised. Six bladed 4.5m diameter fixed pitch monoblock propellers were specified by shipbuilder Fincantieri due to hull vibration modes. The number of blades lowered pressure pulses.
The extensive hydrodynamic experience of the Rolls-Royce Hydrodynamic Research Centre in Sweden was used to design, develop and analyse the rudders and propellers. Model testing was undertaken by MARIN in Wageningen, Holland and at the SVA cavitation tunnel at Potsdam in Germany. The tests confirmed very good cavitation performance.
Promas improved performance in all areas - speed, manoeuvrability and noise.
This is achieved by several components. The twisted rudder shape adapts the rudder to the rotation of the propeller slipstream, giving lower drag and better recovery of swirl energy in the slipstream. For slow speed manoeuvring, the cavitation-free steering angle range is also extended, enhancing manoeuvrability.
The rudder bulb reduces hub-vortex losses and has a beneficial effect on the wake field. The hubcap acts as a hydrodynamic fairing. A different design of propeller blade rebalances the loading pattern on the various regions of the blade without increasing propeller induced noise and vibration. During sea trials in early 2015 the ship exceeded expectations in propulsion and manoeuvrability as well as achieving the contracted design speed of 20 knots.
Promas Lite upgrade
The wide ranging project will look at research carried out to date before exploring the business case for autonomous applications, the safety and security implications of designing and operating remotely operated ships, the legal and regulatory implications and the existence and readiness of a supplier network able to deliver commercially applicable products in the short to medium term.
The project is funded by Tekes (Finnish Funding Agency for Technology and Innovation) and will bring together universities, ship designers, equipment manufacturers, and classification societies to explore the economic, social, legal, regulatory and technological factors which need to be addressed to make autonomous ships a reality.
A specific technology work stream will look at the implications of remote control and autonomy of ships for propulsion, deck machinery and automation and control. It will use, where possible, established technology to for rapid commercialisation.
The project will combine the expertise of some of Finland’s top academic researchers from Tampere University of Technology; VTT Technical Research Centre of Finland Ltd; Åbo Akademi University; Aalto University; the University of Turku; and leading members of the maritime cluster including Rolls-Royce, NAPA, Deltamarin, DNV GL and Inmarsat.
The project will run until the end of 2017.
Head of Blue Ocean Team,
Engineering & Technology, Marine
Press release - Thursday, 2 July 2015
Rolls-Royce to Lead Autonomous Ship Research Project
The Unified Bridge from Rolls-Royce has won the Norwegian Design Council 2015 award for design excellence. The awarding jury said: “In a conservative business with many class regulations, it is a challenging task to develop innovative solutions for user interfaces. This solution appears significantly better than competing solutions, and the quality of the interaction design is high. The user interface is based on modern navigational principles. The work surfaces are layered, which enable navigation on one surface, and with the touchscreen reduces cognitive load for operators.”
It is now fifty years since the first Aquamaster azimuth thruster was delivered, the start of a development that has built in size and scope to become a major contributor to today’s Rolls-Royce propulsion product portfolio.
At that point the principle of the azimuth thruster was well known. John Ericsson, the innovator of many technologies in the 19th century, had patented a deck mounted outboard engine, other patents were issued in the US and UK in the 1870s and demonstrated as through hull units on a large scale. In World War II barges were equipped with over-the-stern thrusters with deck mounted engines. But there was not yet a convincing commercial demand. This emerged in the 1970s and has widened ever since.
Aquamaster thrusters began as a diversification for the Hollming shipyard in Rauma, Finland. The yard had originally been established to build vessels as war reparations to the Soviet Union, and was looking for something to even out market fluctuations. This first product was a steerable propeller with a deck-mounted diesel engine, installed on a hopper barge also devised by the yard, and largely made up from tractor and vehicle components. For the first few years production volumes were small , 2-10 units per year in sizes from 100-300hp. The market was there, but the main difficulty was sourcing components. The first exported units went to Germany, then Sweden specified units for propelling rod link ferries.
In England Yorkshire Dry Dock built many small coastal cargo vessels each with two 400hp units. As the expor t market grew, a good name was needed for the product, and it became known as the ’Aquamaster azimuth thruster’. Aquamaster is still a registered trade name within Rolls-Royce. By 1975 thrusters were offered in four sizes from 100 to 800hp and as well as Europe the market had expanded to include the US, Canada and Japan while sales volumes were growing rapidly and marketing companies and agencies were being set up around the world.
It was clear that the market was interested in bigger azimuth htrusters. The problem was in finding durable large bevel gears and other components to handle high powers. Special gears could be prohibitively expensive to buy, and other design constraints might pose a long term maintenance cost. So the R&D problem was to overcome these difficulties, at the same time trying to raise the efficiency of azimuth thrusters above the level of conventional propulsion systems.
A big step came at the beginning of the 1980s with the design of the first unit to be rated at over 1,000hp. This was the Aquamaster 1250. The Finnish oil comapny Neste ordered three tugs equipped with these thrusters and these vessels became a very good reference in the years that followed.
At the other end of the size range the first Aquamaster azimuth thrusters rated at more than 10,000hp were developed in the early 1990s, the initial application being a very demanding one. Ice-strengthened ARC 1 units. Two per ship were supplied to the multipurpose icebreakers Fennica and Nordica, providing both main propulsion and excellent manoeuvring in open water or thick ice. The two vessels are still operating in the same way, providing icebreaking services in the Baltic in winter and acting as offshore support vessels in summer.
The conventional thrusters have also grown in power, and in recent years have proved very attractive for propulsion and positioning of semi-submersible drilling rigs, drilling ships and many other vessel types. The Aquamaster business was restructured and enlarged several times in the years following its birth in the Hollming yard, most significantly when it was merged with the Rauma Repola deck machinery business. This was bought by Vickers plc in 1995 and combined with Swedish Kamewa. From 2000 the thruster and deck machinery product lines have been integrated with products from other origins and further developed to provide today’s comprehensive range of Rolls-Royce thrusters.
Full article - Celebrating 50 years of azimuth thrusters
Rolls-Royce azimuth thruster range
When the 2005 built platform supply vessel Bourbon Topaz docked in the Orskov Yard in Frederikshaven, Denmark during January this year for the overhaul of the four thrusters that propel the vessel, replacement units from the Rolls-Royce Thruster Support Pool were already waiting on the dockside.
On this occasion, due to a delayed start three Rolls-Royce service engineers were present to perform the exchange, but the work would normally be completed with two engineers. The two main propulsion azimuth thrusters, 2,500kW Azipull 120 units with CP propellers, the swing-up TCNS 73 azimuth thruster and the TT2200 tunnel thruster were removed and exchanged with replacement units over an eight day period. The vessel was then returned to operations.
“A conventional well-planned multiple-thruster overhaul at the yard would take around 21 days, but using Thruster Support Pool units really speeded everything up and ensured there were no surprises or delays due to missing or incorrect parts. It was also complete in the agreed time,” said Terje Fjelle of Bourbon Offshore Norway.
The removed units were returned to the Rolls-Royce centre for overhaul and testing, and then returned to the Support Pool.
“We now have a broad range of units in the Support Pool, so with appropriate planning we can deliver similar time savings for other shipowners at a fixed price, which helps with budget planning and ensures the time in drydock is minimised,” says Geir Oscar Løseth, General Sales Support Manager - Ulsteinvik, Norway.
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