Dual-fuelled tug construction in Singapore, Japan and China highlights an exciting trend in terminal tugboat design and operations
Liquefied natural gas (LNG) is playing an increasingly important role in terminal tug design and operations as national and port authorities raise their environmental requirements. Terminal operators are driven by growing government and public concerns over port pollution to consider dual-fuelled tugs to support ship manoeuvring, escorting and handling services.
This has led to tugboat owners adding vessels to their fleet with engines that mainly run on gas, with diesel for piloting and as a back-up. Some of the latest LNG-fuelled tugs have been built and delivered in south and east Asia.
With this background, Keppel Offshore & Marine (O&M)’s shipbuilding arm, Keppel Singmarine, completed its second dual-fuel tug for operations in Singapore in September. Maju Loyalty is an azimuth stern drive (ASD) tug for Maju Maritime, a joint venture between Keppel and Royal Boskalis Westminster.
Maju Loyalty was designed by Keppel O&M for terminal and harbour operations in the busy ports around Singapore. It has an overall length of 32 m, breadth of 12.5 m and bollard pull, ahead and static, of 73 tonnes.
Its propulsion and power comes from a pair of Niigata 6L28AHZ-DF dual-fuel engines. These each develop 1,920 kW of power at a speed of 800 rpm driving two steerable and azimuthing fixed-pitch propellers.
This is the second dual-fuel tug Keppel Singmarine has delivered for Singapore operations this year. In May, it handed over LNG-fuelled tug KST Liberty, to Keppel Smit Towage, a sister company to Maju Maritime. This is also an ASD tug for terminal and harbour operations with 65 tonnes of bollard pull.
Keppel said both tugs deliver economical operations, efficient fuel consumption, a simplified bunkering process and enhanced safety and comfort. The Maritime and Port Authority of Singapore provided co-funding of up to S$2M (US$1.46M) for each tug as part of its LNG Bunkering Pilot Program grant.
These dual-fuel tugs are equipped with containerised, type-C ISO-certified LNG tanks on the main deck. They also have a patented, compact and cost-effective LNG vaporiser. The LNG tanks can be refuelled by truck-to-ship operations or by replacing the empty tanks with replenished ones.
Shell Eastern Petroleum and Keppel O&M have formed a joint venture, FueLNG, for LNG bunkering services to be conducted at Jurong Port. These services will be offered to other gas-fuelled vessels in Singapore.
There are likely to be more LNG-fuelled tugs built in Singapore as Maju Maritime and Keppel Smit Towage managing director Romi Kaushal indicated there was a drive to reduce sulphur, nitrogen and carbon gaseous emissions within these tugboat fleets. “It is a step in the right direction as the industry adjusts to IMO’s global cap of 0.5% on the sulphur content of marine fuel,” he said.
“This [Maju Loyalty] project is a testament to Keppel’s innovation and reliability, and we look forward to furthering this partnership,” he added.
Maju Maritime and Keppel Smit Towage provide harbour assistance, marine support and coastal towage services with a combined fleet of more than 70 vessels.
Japan has also become a leader in LNG-fuelled tug construction projects. Mitsui OSK Lines has two dual-fuel tugs under construction at Japan’s Kanagawa Dockyard Co. The first was launched at the end of September and named Ishin. It is scheduled for completion in February 2019 and the second tugboat is expected to commence operations in April 2019.
These will be operated by Nihon Tug-Boat Co with the LNG fuel supplied by Osaka Gas from Sakai Senboku Port. They will be the first LNG-fuelled vessels, outside of gas carriers, to be constructed in Japan to the international code of safety for ships using gases or other low-flashpoint fuels (IGF Code).
Yanmar delivered two 6EY26DF dual-fuel main engines for the first tug. Yanmar also received orders for the LNG fuel tanks, buffer tanks and gas combustion devices that will be part of the gas fuel feed systems for the engines.
In June, Yanmar diesel engine design director Yohei Kamata told Tug Technology & Business that it was progressing with engineering for these engines.
Yanmar’s dual-fuel engine uses diesel as a pilot and as a back-up to natural gas. The 6EY26DF engine has a shaft output of around 1,500 kW, while the larger alternative, 8EY26DF engine generates about 2,050 kW of power. Both achieve this performance at running speeds of 750 rpm.
When using natural gas, Yanmar said these engines emit 80% less NOx, 99% less sulphur and particulate matter and 25% less CO2 than conventional diesel engines.
China is also progressing with LNG-fuelled tug construction with four in operation and a fifth under construction at Jiangsu Zhenjiang Shipyard. This latest newbuilding will be built to a Robert Allan RAstar 3800-DF tug design for completion in 2019.
It will be an ASD tug for operations by Ningbo Zhoushan Port Co. It will have a pair of Niigata 8L28AHX dual-fuel engines, each driving a Rolls-Royce US 255 controllable pitch Z-drive. When this tugboat is delivered, it will have a bollard pull of around 80 tonnes and LNG storage capacity of 55 m3.
Last year, Equinor (formerly Statoil) started using three LNG-fuelled tugs at its production terminal in Hammerfest, Norway. Dux, Pax and Audax are operated by owner Østensjø Rederi in Arctic conditions year-round to escort LNG carriers into and out of the terminal in temperatures down to -20˚C.
These were built by Astilleros Gondán in Spain to a Robert Allan RAstar 4000-DF design and Bureau Veritas classification with Wärtsilä dual-fuel engines. They can achieve a maximum free-running speed of 15 knots and can produce up to 107 tonnes of bollard pull.
Maju Loyalty particulars
Owner: Maju Maritime
Builder: Keppel Singmarine
Designer: Keppel O&M
Area of operations: Singapore
Type: terminal/harbour tug
Length, oa: 32.00 m
Beam, moulded: 12.50 m
Bollard pull: 73 tonnes
Main engines: 2 x Niigata 6L28AHZ-DF
Power: 1,920 kW at 800 rpm
Fuel: containerised LNG tanks
Bunker services: FueLNG
Rimorchiatori Riuniti Panfido has ordered a tug and pontoon barge combination for supplying LNG and marine gas oil fuel along the Italian coast of the Adriatic Sea.
This unit will include an LNG-fuelled tractor tug that will tow a non-propelled pontoon to supply LNG and diesel to ships in the region around Venice.
Spanish naval architects SENER designed the tug and pontoon. The tug will be built for towing, escorting, rescue, supply and salvage operations, be propelled by Voith thrusters and have a bollard pull of 60 tonnes.
It will be equipped with FiFi 1 fire-fighting system with twin monitors, with a small deck crane and winches on the fore and aft decks for towage.
The pontoon barge will have capacity to hold 4,000 m3 of LNG and 1,000 m3 of marine diesel oil cargo. It will have a loading arm and two large tyre-based cylindrical fenders on both port and starboard sides for bunker operations, four large LNG cargo tanks on the deck and a gas boil off management system. This project is cofunded by the European Union through the Poseidon MED II programme.