There has been a shift in requirements for tug orders, with an emphasis on reducing emissions through innovation
Designers, shipyards and owners have responded to the rising pressure on operators to reduce emissions in ports and around coastlines with more tugs being built to comply with stricter emissions requirements – IMO Tier III or US Environmental Protection Agency (EPA) Tier 4 for example – with some opting for hybrid and electric propulsion.
Tugs owners are also considering alternative fuels, with LNG still the leading contender compared with diesel.
These changes must not impact the safety, performance, stability or bollard pull of tugs, as ships visiting ports are becoming larger, with ultra-large container ships of more than 23,000 TEU on trans-oceanic routes.
Here we highlight these growing trends by presenting the most technically advanced tugs delivered in the past 12 months.
Gisas Shipbuilding Industry took a bold step towards minimising its environmental footprint when the world’s first all-electric tug was delivered at the end of 2019. Gisas Power has demonstrated the performance possible from powering tugs with batteries and shore power. It became a symbol of what the future holds.
Gisas Power was built at TK Tuzla Shipyard to a Zero Emissions Electric tug (Zeetug) design by Navtek Naval Technologies, who collaborated with Turkish power systems integrator BMA Technology, drive and converter supplier ABB and energy storage systems provide Corvus Energy on this industry-first project.
Istanbul-based Navtek general manager Ferhat Acuner explained the technology on Gisas Power during Riviera’s Maritime Hybrid, Electric and Fuel Cell Webinar Week and Tug Technology Webinar Week during Q3 2020.
It is the first tug built to a Zeetug30 design. Gisas Power has an overall length of 18.7 m, beam of 6.7 m, hull depth of 4.7 m and design draught of 3.5 m. Its propulsion generates a bollard pull of 32 tonnes and provides a service speed of 10 knots.
Gisas Power draws all its power from two Corvus Energy 1,450-kW lithium-ion battery packs. For safety, the tug has two redundant battery rooms, one fore and one aft, that are maintained at a constant temperature by a cooling system.
Most tugs built with hybrid propulsion include shaft generators and electric motors, some even have energy storage systems.
Early in Q1 2020, an alternative approach to hybrid propulsion was demonstrated on a tug newbuilding. Sanmar Shipyards built Boğaçay XXXVIII to a Robert Allan design and the world’s first advanced variable drive (AVD).
This is a unique application of hydro-mechanical hybrid propulsion in the marine segment, with technology supplied by Caterpillar. A primary advantage of an AVD is the continuously variable transmission, which can modulate propeller speed down to zero revolutions by a slipping clutch.
AVD can also spin the propeller faster than would be possible if the engine was directly coupled to the drive. This enables engines to operate in their peak efficiency zone instead of operating along the propeller demand curve at higher fuel oil consumption resulting in significant fuel savings.
With a fixed-pitch propeller pitched for bollard conditions at zero knots, this feature enables full power to be taken from the engine when free running, much like controlled-pitch systems.
Boğaçay XXXVIII was built to a RAmparts 2400-SX design and ABS class for an A1 towing vessel with 70 tonnes of bollard pull. It has an overall length of 24.40 m, moulded beam of 11.25 m, a hull depth of 4.38 m and a maximum draught of 5.40 m.
In the US, more harbour tugs are being built with propulsion systems compliant with EPA Tier 4 emissions reduction requirements. It is a legislative rule and increasingly expected by US ports for new escort and harbour tugs.
Foss Maritime, part of the Saltchuk Marine family of companies, ordered a series of EPA Tier 4-compliant escort tugs for assisting ships into US west coast ports.
At least four of these were ordered from Nichols Brothers Boat Builders in Freeland, Washington state, of which the first two – Jamie Ann and Sarah Averick – have been completed. The other two will be Leisa Florence and Rachael Allen.
These azimuth stern drive ASD-90 class tugs are built to Jensen Maritime’s Valor design, to US Coast Guard’s Subchapter M regulatory standards and with ABS’ Loadline certification.
They each have two MTU series 4000 main engines driving Kongsberg’s US255 azimuth thrusters. For Tier 4 compliance, they have selective catalytic reduction systems for removing NOx emissions.
Foss’ ASD-90 tugs have overall length of 31.7 m, moulded beam of 12.2 m and moulded hull depth of 5.2 m, plus 90 tonnes of bollard pull.
Great Lakes Towing is carrying out a large newbuilding campaign with at least six tugs either being built or delivered from its own shipyard in Cleveland, Ohio with hybrid propulsion on board.
It christened the fourth of these (2019-built Pennsylvania) and fifth (2020-built Wisconsin) in December 2020.
These icebreaking tugs are replacing elderly vessels, some over 50 years old, said Great Lakes Towing president Joseph Starck during Riviera’s Hybrid and electric tug viability: the future’s bright webinar, on 3 September.
These tugs are built to a Damen Stan tug 1907 Ice design with more than 30 tonnes of bollard pull and are powered by two MTU 8V4000 Tier III diesel engines driving three-bladed Kaplan style propellers in Kort nozzles. They each have two John Deere/Marathon generator sets and a hybrid power system supplied by Logan Clutch Corp and installed by Canal Marine & Industrial.
Yong Gang Xiao Tuo 60
Outside of North America, owners and port operators have invested in LNG-powered tugs and bunkering infrastructure. In China, Ningbo Zhoushan Port has gained LNG bunkering experience with dual-fuel tug Yong Gang Xiao Tuo 60.
This 750-gt tug was built to a Robert Allan RAstar 3800-DF design by Jiangsu Zhenjiang Shipyard, and delivered at the end of 2019. It has China Classification Society (CCS) notation for port and coastal operations and for fire-fighting.
Dual-fuel Niigata 8L28AHX-DF main engines provide 2,389 kW of power at 800 rpm to Kongsberg US 255 controllable pitch (CP) Z-drives, providing a top speed of 13.5 knots and bollard pull ahead of 80.3 tonnes.
Gloryholder Liquefied Machinery supplied the fuel gas system and deck-mounted LNG tank with gross storage capacity of 55 m³, giving this tug a range of more than 700 nautical miles in gas mode. This can be supplemented by an additional range of nearly 1,700 nautical miles when the engines are in diesel mode, from gross fuel oil storage of 83.3 m³.
Jin Gang Lun 33
Also in China, shipyards are completing tugs to a new CCS notation denoting their intelligent online systems. This is a growing trend in tug construction and operation with more monitoring, alert and intelligence deployed in tugs. Sanlin Shipyard of Shanghai Harbour Fuxing Shipping Service delivered two tugs, Jin Gang Lun 33 and Jin Gang Lun 34, to Tianjin Port. These have CCS class notations for coastal services, ice class B and Rules for Intelligent Ships. This I-ship consists of N – intelligent navigation; M – intelligent machinery; E – intelligent energy efficiency management; and I – intelligent integrity platform.
Their main roles include harbour towing, berthing and unberthing visiting ships, ice breaking and emergency response with fire-fighting systems.
During sea trials, these 34.6-m tugs achieved a maximum bollard pull ahead of 51 tonnes and free running speed ahead of 13 knots. They each have two Daihatsu diesel engines, each rated for 1,471 kW at 750 rpm. These drive Kawasaki KST-180ZF/E Z-drive units with a 220 cm diameter propeller.
Boluda Towage Europe is one of the first owners to order, receive and operate a harbour tug built to IMO Tier III requirements in Europe. It brought two into service in Port of Zeebrugge, Belgium in December.
Azimuth stern drive (ASD) tugs VB Bolero and VB Rumba were designed and built by Damen Shipyards in Vietnam.
They were built to an ASD 2813 design with 85 tonnes of bollard pull. Their propulsion includes selective catalytic reactors to remove NOx emissions and filters to prevent particulate matter, to comply with IMO Tier III.
Boluda ordered these tugs after securing a five-year concession extension in September 2020 and committed to reducing emissions from harbour operations by upgrading existing tugs to IMO Tier III and introducing new tugs at these standards.
Boluda retrofitted tug Union Koala to the IMO Tier III standards in 2019 and is retrofitting Union Panda in 2020. It will retrofit the rest of its Zeebrugge fleet in the first two years of the concession contract.
Remontowa Shipbuilding is building a series of tugs for the Polish Navy, starting with Bolko. These were built in the B860 tug programme for towing naval ships and logistics services in the Baltic Sea.
They are also available for salvage and emergency support, pollution control and removing hazardous material from the water along the Polish coast.
So far, Remontowa has completed three of a series of six B860 tugs, with Bolko and Gniewko entering service during Q1 2020. Mieszko officially entered service and Semko underwent sea trials in August. The other two tugs, Leszko and Przemko, were launched in Q3 2020.
These tugs have sufficient ice class to enable them to operate in severe ice conditions accompanied by icebreakers. They have a bollard pull of around 35 tonnes coming from a pair of Rolls-Royce MTU diesel engines driving two Schottel rudderpropellers.
Caspian Offshore Construction deployed new shallow-draught ice-class tug Caspian Fauna in Aktau Port, Kazakhstan, in June.
This 30-m tug was built by Aksoy Gelibolu Shipyard with a draught of just 1.8 m and bollard pull of 25 tonnes. It is classed for unrestricted navigation, for anchor handling and with ice-class 1D.
Caspian Fauna has a beam of 11 m and hull depth of 3.20 m. Its propulsion comes from two main diesel engines with power ratings of 970 kW each. Combined, these produce 1,940 kW to power two propellers through reduction gears.
Seaplace developed the design and carried out structural engineering using subsystem V80R3.0 for naval architecture and detailed hull and internal structural engineering from Sener’s Foran V80 system.
Brusco Tug took delivery of a new 307-gt escort tug from Diversified Marine in Portland, Oregon and it was chartered to Crowley Maritime to support ships on the US west coast.
This ASD tug was built to Robert Allan’s RApport 2500 design with a bollard pull of 89 tonnes ahead and 87 tonnes astern. This is formidable power from a tug with an overall length of 25 m and moulded beam of 12.2 m.
Hercules has a full Caterpillar Marine propulsion suite, complying with US EPA’s Tier 4 emissions requirements.
This includes twin Cat 3516E main engines that develop 2,240 kW at 1,800 rpm driving Caterpillar (now Berg Propulsion) MTA 627 azimuth thrusters with 2.7 m diameter propellers, connected by carbon-fibre shafts. It has a high-performance Markey winch as part of its deck machinery package.
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