Waterjet manufacturers deal with weighty matters

Lighter, more powerful waterjets are enabling passenger ferry operators to combine high speed with more economic, environmentally friendly performance

For fast ferry applications, weight is always a key factor when selecting water jet technology, alongside power, environmental performance and durability. Consequently, introducing lighter waterjet technology has been a key area of focus for several companies active in this sector.

Wärtsilä has been investigating the benefits of designing its modular waterjets using duplex stainless steel. Those components that come under the highest stress, the shaft and impeller, have already been delivered to some customers in duplex stainless steel, but Wärtsilä has now also made the outboard parts available in this material instead of 316 grade stainless steel.

According to the company, constructing the outboard as well as internal components in duplex stainless will save around 1,250 kg on a LJX1500SRI waterjet of the type now being applied on most fast ferries, with an engine power of 9,100 kW per jet installed onboard. The technical challenge for Wärtsilä’s design teams has been to create waterjets that are strong enough to withstand the propulsive stresses, but are as light as possible to improve the performance and fuel efficiency of the vessel. The company believes this challenge has been successfully met.

Reliability and ease of maintenance are also key customer prerequisites, which Wärtsilä has responded to with the LJX1500SRI model featuring an inboard hydraulics arrangement. Over the past year, the company has secured four contracts to supply waterjets on newbuild fast ferries, two each at Incat Tasmania and Austal Australia, which all feature inboard hydraulics.

Wärtsilä Marine Solutions sales manager, waterjets, Jeroen Vedder said “The major advantage of inboard hydraulics is that all of the cylinders and hoses are mounted inside the vessel, and so they are not exposed to hostile conditions outside the vessel, including seawater. Another advantage is the fact that maintenance on these components can be undertaken inside, and so any potential oil leaks into seawater are avoided.”

The two new fast ferries ordered from Incat are being prepared for Malta-based Virtu Ferries and the Spanish company, Naviera Armas. These contracts continue a close working relationship between Wärtsilä and Incat that stretches back around 30 years and has seen the delivery of 174 modular waterjets to date to Incat’s Tasmanian shipyard.

Wärtsilä will supply four LJX1500SRI waterjets and a Protouch control system to Incat for the 110 m long Virtu Ferry craft, which will operate between Malta and Sicily. The fast ferry is scheduled for delivery towards the end of 2018 when it will become the largest high-speed catamaran in the Mediterranean, carrying 900 passengers and 167 cars at a service speed of up to 38 knots.

Meanwhile, Wärtsilä will supply a further four LJX1500SRI waterjets and a Lipstronic control centre for a 109 m high-speed ferry for Naviera Armas at Incat, which is due for delivery in 2019. For both projects Wärtsilä engineers will be involved at the yard in commissioning the waterjets and then for the initial sea trials.

For another long-term partner, Austal, Wärtsilä has been contracted to supply four of its waterjets, the hydraulics and control systems for a new 109 m long high-speed ropax ferry for Molslinjen of Denmark. Wärtsilä’s compact axial flow jet solution was considered the most appropriate choice for this vessel, since it fully met the customer’s weight and performance criteria. The all-aluminium catamaran will have a top speed of 40 knots and will be able to carry up to 425 cars and over 1,000 passengers on a route between Aarhus and Odden. Wärtsilä is due to deliver its waterjet systems to the yard in May this year, with final delivery of the vessel Q4 2018.

Mr Vedder added “The design of the LJX1500SRI waterjet encompasses high levels of efficiency, excellent hydrodynamic performance, low noise and reduced maintenance. As a result it is rapidly becoming the waterjet of choice for owners and shipyards worldwide.”

One of the main requirements for fast ferries is, of course, reliability and performance. Mr Vedder said “Fast ferries operate on tight schedules and owners expect that the equipment on board is able to operate without any problems to meet their promises to their passengers. Our technology is well proven with an extensive reference base backed up by an excellent service network that is able to meet our customers needs for waterjet maintenance and repairs.”

Environmental factors are a further key influence on Wärtsilä’s waterjet design development programme. Mr Vedder added “We are working a lot on environmentally friendly solutions at the moment. For example, we are currently developing a system with dual-fuel engines, using diesel or LNG, in combination with waterjets.”

Weight and space 

Rolls-Royce is another leading waterjet supplier for the high-speed ferry market, and the ongoing customer requirement for compact, low-weight systems is also reflected in some of its recent projects, including SeaStar II, which was delivered by Austal from its Philippines shipyard last year. A 50 m catamaran designed by Incat Crowther for South Korean operator Seaspovill, the ferry can carry up to 450 passengers at 40 knots.

SeaStar II features S56-3 waterjets mounted in pairs on two common base plates to provide a lightweight and compact propulsion arrangement. Rolls-Royce designers were able to trim away the edges of the reversing buckets without causing any significant loss of sideways thrust, making the jet system as narrow as possible. All four waterjets have steering and reverse capabilities, to ensure the ferry is agile, with a high degree of manoeuvrability and propulsion redundancy.

Rolls-Royce sales manager, Australia, Richard Dreverman said “This order was rather special for us as the catamaran is designed for low resistance and low wash, and consequently has very fine-lined hulls and limited space at the stern. Putting two type S56-3 waterjets together on a single base plate allows us to save a significant amount of space.”

Rolls-Royce waterjets have also been specified for a 56 m long, 35 knot passenger catamaran also under construction at Austal’s Philippines yard for operation in German coastal waters. Förde Reederei Seetouristik will use the vessel on a service between Hamburg and the island of Heligoland. Because the route is partly in open sea and partly along the River Elbe, reduced wash was a key requirement, Rolls-Royce points out. In this case four S71-4 waterjets will propeller the catamaran, each powered by a 16-cylinder MTU 4000 series engine.

More recently, Rolls-Royce has been selected to supply a combination of its Kamewa waterjets and MTU engines for three 42 m high-speed ferries being built at Brodrene Aa in Norway, which will operate between Hong Kong and Guangzhou, China. The waterjets for these ferries will be manufactured from duplex stainless steel to achieve lower weight and high levels of durability. The company said the fuel savings from specifying a highly efficient pump unit combined with the design of the steering and revising units will also aid faster and more accurate manoeuvring.

Brodrene Aa chief executive Tor Øyvin Aa commented “The lightweight and high power capabilities of the Kamewa steel series waterjets along with the proven power output and reliability of MTU engines in fast ferries makes Rolls-Royce a logical choice for this type of vessel.”

The ferries, to be operated by Zhongshan-Hong Kong Passenger Shipping Co-op Company, are of two designs. Two out of the three will have a capacity of 300 passengers and will operate at speeds of up to 40 knots. This pair will feature four Kamewa S56-4 type waterjets and four MTU 12V 2000M72 engines. The third fast ferry will be designed to carry 230 passengers at up to 37 knots and will be powered by two MTU 16V2000M72 engines, each driving a Kamewa S63-4 waterjet.

Rolls-Royce offers waterjets in both aluminium and steel. Its aluminium series, which provides propulsion for smaller vessels with units up to 2,000 kW, offers a high volume flow from the axial pump with a good driving thrust at lower speeds. Rolls-Royce’s latest steel series waterjets provide propulsion over a wider range, from 450 kW to over 30,000 kW, and the mixed flow pump’s stainless steel construction makes it highly durable. Indeed, the company points out that the average time between overhauls is set as standard to 15,000 hours and if any maintenance is required the pump unit is of an easily removable plug-in design.

Focus on efficiency 

One of the leading providers of waterjets for smaller passenger ferries is New Zealand’s HamiltonJet. The company’s latest addition to its portfolio is the HT range, which currently covers the three largest sizes of waterjet offered by HamiltonJet – the HT810, HT900 and HT1000.  

Global business development manager, Antony Tomkins said “These represent a significant step forward in the overall operational spectrum of our waterjets, bringing a substantial increase in high-speed efficiency, whilst maintaining the traditional HamiltonJet advantages of good mid-speed thrust and excellent control and manoeuvrability. These jets have already proved very successful in the oil and gas and military markets, and as we see a resurgence of the high-speed ferry market they are now proving popular in this sector too.”

Meanwhile, there have been evolutionary improvements to the company’s existing range over the past few years including the introduction of the JT Steering system, which has replaced the traditional deflector steering mechanism with a steerable nozzle assembly.

Mr Tomkins said “This has had a significant impact on the passenger vessel sector, as the improvement to steering efficiency allows the operator to either run a faster service or reduce speed and save fuel whilst still running the same timetable. In addition, the superior steering efficiency combined with the higher mid-range thrust of the HamiltonJet system means that higher levels of overall performance can be maintained when rough weather is experienced, allowing operators to keep to their timetables more reliably.”

The company has also improved its Blue Arrow control system for smaller jet ranges, typically up to 1,000 kW. The JetAnchor add-on gives operators the ability to have a stationkeeping system with two modes; one which allows high precision stationkeeping, and another that allows good positional accuracy with a lower fuel burn and better crew comfort, but enables the vessel to swing around a 'virtual anchor' set by the GPS.

The other control innovation HamiltonJet introduced to the market last year was the XCI module, which gives operators the ability to add an autonomous operational capability to waterjets. “Traditionally this has been something that was only of interest to our military customers, but we are now seeing this as an increasingly interesting proposition for our commercial clients as well,” added Mr Tomkins.

HamiltonJet has recently won significant new ferry contracts including Red Funnel’s Red Jet 7, currently under construction at Wight Shipyard, which will be the first newbuild ferry ordered by Red Funnel to feature HamiltonJet systems. The ferry will be fitted with four HM 571 type waterjets. The company is also supplying three new 43.5 m ferries capable of 34 knots for WETA’s operation in the San Francisco Bay Area. These will be the first fast ferries to feature the company’s new HT810 jets.

HamiltonJet has an active R&D programme and promises exciting new product launches later this year. Mr Tomkins added “Our R&D teams are constantly looking at ways in which we can increase the overall efficiency of our jets and the way in which our control systems can be used to exploit the best benefits from our systems with maximum ease of use.”

ABB reaches Azipod cruise ship milestone

A leading supplier of azimuthing thrusters, ABB is continuing to win cruise ship contracts for its electrically driven podded propulsion concept

In 1990, the Finnish Board of Navigation vessel, Selli, was fitted with the first Azipod propulsion system following its conversion by ABB. This was the starting point for the launch of a new generation of azimuthing propulsion systems, which has found particular favour in the cruise shipping business.

Around five years after the successful trials on Selli, the first order for a cruise ship was received from Carnival Cruise Lines for its Fantasy-class newbuildings Elation and Paradise. Many more have followed over the past two decades and ABB recently passed the 100-cruise ship milestone for Azipod installations, with an order to supply the French’s company Ponant’s latest polar expedition cruise ship.

Ordered from the Norwegian yard, Vard Søviknes, the vessel is designed to undertake demanding Arctic and Antarctic cruises and will be fitted with Azipods with 6 m propellers and a combined power rating of 34 MW to allow the vessel to operate through ice-covered seas and achieve greater manoeuvrability and low noise and vibration levels.

Another recent contract demonstrating Azipod’s popularity amongst niche, expedition-type cruise operators, is an order to supply propulsion solutions for a new vessel ordered by Lindblad Expeditions Holdings that will also take passengers on cruises in polar waters. ABB claims it was the only supplier of azimuthing electric podded propulsor systems of sufficiently high ice-going class able to meet this owner’s requirements.

While the Ulstein Verft-built Lindblad vessel, due for delivery in 2020, will be equipped with Azipod DO units, the contract for Ponant includes two Azipod VI units, which are claimed to be the most powerful azimuthing propulsors on the market. The Ponant vessel will be built to Polar Class 2 ice class and is the first commercial application of the Azipod VI for both icebreaking and open water operation in high arctic conditions. 

“Azipod VI propulsion is a unique azimuthing solution for ice applications in a power range between 5 and 17 MW,” said ABB Marine and Ports head of passenger, ice and dry cargo Marcus Högblom. “With a built-in high-efficiency AC motor and fixed-pitch propeller mounted directly on the motor shaft, it stands out from other thruster solutions. While mechanical thrusters have complex transmission with gears and shafts, Azipod propulsion has only electrical cables between the power source and the thruster unit and this makes it possible to build an extremely robust propulsion device with the simplicity, strength and reliability for the most challenging ice conditions, and to any ice class.”

Mr Högblom added “Since Azipods were first installed on the Carnival cruise ships, we estimate that energy savings equivalent to 700,000 tonnes of fuel have been made in the cruise sector due to the selection of Azipod propulsion, while over 400,000 passengers have perhaps unknowingly benefited from the greater manoeuvrability, lower noise and lower vibration levels that Azipod propulsion achieves.”

ABB is also supplying Azipod propulsors for a new LNG-powered Viking Line cruise ferry that is being built in China by Xiamen Shipbuilding Industry. The newbuilding will feature twin XO 2100 type Azipods and this is believed to be the first time a cruise ferry has opted for a podded propulsion system of this type.

“Following on from our power and propulsion systems role with the pioneering Viking Grace, we are very excited that the continuation of our co-operation with Viking Line involved the groundbreaking order for azipod propulsion for this cruise ferry,” said Mr Högblom.

ABB’s success in the cruise sector in recent years has largely been based around the popularity of the Azipod XO technology, which is designed for high-power open water applications. The world’s largest cruise liner, Symphony of the Seas, delivered to Royal Caribbean in April 2018, features Azipod XO units following their successful use on board several earlier vessels for this company including Quantum of the Seas, which was the first vessel to utilise XO technology.