Classification societies have a crucial role to play, not just in ensuring the safe operation of the global tug fleet but also in developing new technical solutions to meet the evolving requirements of tug operators and their customers.
One of the main protagonists in this sector is Bureau Veritas (BV), which has implemented a number of important initiatives over the past 12 months or so. The BV-classed fleet of tugs has grown steadily over recent years and now stands at more than 1,700 vessels, which makes BV the global leader in tug classification.
That position clearly comes with responsibilities. “We are strongly committed to supporting tug owners, builders, designers and equipment manufacturers in their efforts to achieve excellence in safe, clean and efficient towing operations,” says Gijsbert de Jong, BV’s business development manager for offshore service vessels and tugs. “Moreover we will continue to strive towards a harmonised international regulatory framework which is open to innovation and progress.”
Building on the results of the SafeTug joint industry project co-ordinated by Marin, the Dutch maritime research institute, BV has been working with leading industry partners to develop its Safety Guidelines for Design, Construction and Operation of Tugs. The guidelines, which were first presented and released in June 2014, aim to create a rationalised and harmonised regulatory framework for tugs in order to improve safety while supporting innovation. The latter is very important, notes Mr de Jong, as the towing industry is heavily focused on technology development and new design concepts to improve performance and operational safety.
“A pragmatic approach has been taken, whereby the technical requirements are a direct function of the selected class notation as defined on the basis of the operational profile and duties of the tug. The guidelines primarily focus on safety-critical aspects of tugs, including stability during towing and escorting operations, as well as requirements for the design and operation of towing equipment,” adds Mr de Jong.
Many tugs, due to their small size, are not covered by the Solas Convention. In such cases, safety equipment should comply with the national regulations of the flag state, if they exist. BV accepts that the wide variety of different regulations poses challenges for ship design and operation, in particular for the development of standard tug designs.
As an alternative, the BV guidelines propose harmonised standards for fire safety, lifesaving appliances, radio installations and navigation equipment by means of a practical safety matrix. The safety equipment requirements take into account crew familiarity with the operating area and the availability of emergency shoreside support by means of a limit on sailing time from a safe sheltered anchorage.
Design capability limits are included in the proposed class notations for enhanced clarity. The reference towline force for harbour tugs and seagoing tugs involved in normal towing operations is the bollard pull. For escort tugs, the reference towline force is the maximum steady towline force during escorting. In the class notation for escort tugs the towline force is translated into the corresponding maximum steering and braking forces, while the maximum escort speed is also included.
The stability criteria in the BV guidelines are based on the reference towline force. The design loads for the strength assessment of the towing equipment are obtained by multiplying the reference towline force by a factor to account for dynamic effects. The winch brake holding load is also considered a design parameter.
The guidelines include a set of definitions of escort modes and associated forces, whereby escort operations in open sea areas and in calm water are considered. The inclusion of escorting in calm water conditions reflects increasing demand from port authorities to assign an escort tug notation to harbour tugs involved in indirect towing operations during ship-assist operations in port.
Particular attention has been paid to the determination of the design capability limits of escort tugs. “Computer simulations for escort performance prediction have become increasingly sophisticated and reliable,” says Mr de Jong. “Methodologies compliant with the acceptance criteria included in the guidelines may be used as an alternative to full-scale tests to determine steady towline forces and associated heeling angles.” BV has reviewed a number of different methodologies, including computational fluid dynamics (CFD) based simulations, and has accordingly developed a process for issuing Approval in Principle.
Having consulted with industry partners, BV has now started the process of integrating the tug guidelines into its classification rules. “As leading designers and shipyards have already started to develop new tug designs on the basis of the guidelines, their experience will be used as feedback for improvement,” Mr de Jong confirms. In addition, further work is being undertaken to extend the applicability of the guidelines to innovative designs, in particular for tugs with multiple longitudinally distributed propulsion units, such as the Eddy Tug and Rotortug concepts.
Another classification society that is very influential in the tug sector, Lloyd’s Register (LR), has been steadily increasing its market share. It now claims around 30 per cent of the current tug orderbook and 10.6 per cent of the existing fleet. Tug business amounts to about 50 per cent of LR’s global small ship development activities.
Mark Darley, vice president and South Asia marine manager, says: “What is key to ensuring we maintain and grow within this segment is an understanding not only of the owners’ operational preferences, but also the challenges faced by the designer, yard and key equipment and component stakeholders. The small ship industry is becoming increasingly complex as the marketplace demands higher utilisation and this, coupled with the increasingly higher demand for environmentally friendly solutions, is forcing many small ship stakeholders to turn to innovative solutions and previously untried concepts.”
Almost all of the leading industry players now offer some form of cost effective alternative and more environmentally friendly propulsion system. LR highlights Svitzer’s ECOtug and the Damen 2810 Hybrid as good examples, where it has had involvement. Taking advantage of its market leading position in terms of classing gas powered ships, LR is now working closely with designers, operators and builders involved in the development of pure gas powered tugs, including LNG, LPG and CNG designs. This work covers both newbuilds and retrofits.
Another example of an innovative tug project that has LR involvement is, again, for Svitzer. The company is building a series of hybrid tugs for deployment in support of an LNG terminal contract with Chevron on remote Barrow Island in Western Australia. This needed several novel concepts to ensure that the vessels were in harmony with the environment. In particular, the needs of the turtle population breeding adjacent to the terminal had to be considered.
Highly manoeuvrable diesel-electric hybrid tugs were designed to operate with non-hydraulic deck equipment, low-reflection paint, double wall fuel tanks, solar panel water heating and onboard water recycling. LR worked with Singapore’s ASL shipyard, Svitzer Copenhagen and Svitzer Australia, the Australian flag state administration AMSA and many systems suppliers to ensure the safety and performance of the unique features of these tugs.
These include a battery bank that will be kept topped up from a 125A shore power connection generated using LNG fuel, or from the main engine; five-bladed low wash propellers; an exhaust spool unit that will enable an exhaust reactor to be retrofitted; and a dedicated urea tank to enable compliance with Tier III regulations.
Mr Darley says: “Irrespective of ship type, all class societies need to ensure that they understand and work with the segment stakeholders in providing pragmatic solutions that do not hinder innovation or development, yet still provide a framework for designers and assurance for owners. The tug market is no different. In order to maintain and grow our market, it is important that we continue to listen to and work with the industry in addressing the challenges. Right now these relate primarily to operational flexibility, cost and environmental credentials.”
In the short term, LR is working on further enhancements to its tug rules to give designers the tools they need. Separately the class society is also working with tug equipment manufacturers to provide solutions to alternative fuel and propulsion technology choices.
One of the key developments in the classification society sector over the past 12 months or so has been the merger of Det Norske Veritas (DNV) and Germanischer Lloyd (GL). There is now an ongoing project to amalgamate the legacy requirements of the two societies into a common set of tug rules. The new combined rules for tugs are expected to be released in 2016. Christian Andersson, head of special ships, offshore support vessels and conversions, says: “We do not anticipate any major changes. Rather, the new rules will be based on a ‘best of both’ set of principles.”
The recently-merged DNV GL is undoubtedly going to be a major force in the tug market, with 945 tug vessels in its class, including harbour and ocean-going tugs. While there is a geographically diversified fleet classed with DNV GL, it has a particularly significant share of the market in Germany and Southeast Asia, including Singapore, Indonesia and Malaysia.
“We are also especially strong within the escort tug segment and have a leading position as far as tugs using advanced, innovative technology are concerned, such as those designed to use LNG as fuel,” says Mr Andersson. He cites the ground-breaking tugs built last year at Sanmar for Buksér og Berging, which have the DNV GL Gas Fuelled notation, as a good example.
Also active in the development of tugs designed to use LNG as fuel is Japan’s ClassNK, which updated its Guidelines for Gas Fuelled Ships in January. The guidelines provide comprehensive, up-to-date information on key design features relating to bunkering, hull structure, fire safety and explosion prevention measures.
Japan’s first newbuilding project for an LNG-powered tugboat is currently underway. Right from the beginning of the project, ClassNK has collaborated with the owner, the shipyard and the engine manufacturer to ensure an optimum design, the availability of infrastructure in Tokyo Bay and compliance with the safety demands of the LNG fuel system.
ClassNK suggests that the tug will lessen environmental impact by reducing CO2 emissions by about 30 per cent, NOx by about 80 per cent and SOx by as much as 100 per cent. In addition to providing technical assistance, ClassNK completed the design approval, trial operational testing, and the overhaul inspection of the LNG engine in just two months before granting type approval in December 2014. In another environmentally-centred project, ClassNK has been involved in the development of Japan’s first hybrid tugboat with a diesel engine and electric motor for propulsion.
ClassNK says: “As a result of worldwide environmental concerns, international regulations are becoming more stringent. Additionally, local rules for exhaust gases and tax benefits for using clean fuel already exist in several countries, such as the tonnage tax regime in Norway. These affect the tugboat market now and will continue to do so in the future.”
As a result of the ongoing expansion of its global activities, the number of tugs on the ClassNK register has increased recently, accounting for roughly 10 per cent of all vessels classed over the past year or so. At the end of 2014, ClassNK had 713 tugs under class, and 74 of these – the majority of which are newbuildings – have joined the ClassNK register in the last 12 months.
ClassNK is particularly strong in the Southeast Asia market with approximately 600 tugs or 88 per cent of all ClassNK tugboats registered with either Indonesian, Malaysian or Singaporean flags. “We have created strong relationships with these countries through providing quality service and technical support to shipyards in Asia. As a result, the tugboats on ClassNK’s register account for some 37 per cent of all IACS [International Association of Classification Societies] registered tugs in the region,” says a ClassNK spokesperson. “Many of our Southeast Asia registered tugboats are relatively new. The average age is only seven years old and more than 80 per cent of ClassNK tugs in Southeast Asia have been built in the last 10 years.”
Currently ClassNK has limited involvement in the US market, but it believes that regulatory changes may open doors to it and to other societies in future. The spokesperson suggests: “A big change is coming in the US and class will need to build its organisation, competencies and offerings to apply its valued expertise, guidance and assurance within the sector.”
The United States Coast Guard’s (USCG’s) Subchapter M Final Rule, which aims to promote safer work practices and reduce casualties on towing vessels in the US by requiring that vessels adhere to prescribed safety standards and safety management arrangements or to an alternative, annual USCG inspection regime, is expected to enter into force by August this year. “This will expedite the inclusion and relevance of class entering into the broader conversation with US stakeholders,” ClassNK concludes. TTB
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