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Marine Propulsion & Auxiliary Machinery

Marine Propulsion & Auxiliary Machinery

Tug innovations drives class rule developments

Wed 31 Jan 2018 by Martyn Wingrove

Tug innovations drives class rule developments
Bureau Veritas classed dual-fuel Audax, which operates at Statoil's LNG plant in Norway (credit: Astilleros Gondán)

Bureau Veritas’ global leader for tugs and offshore vessels Eva Peño explains the latest regulatory and technical developments that are influencing new tug class rules

Bureau Veritas (BV) issued new rules for the classification of tugs and offshore support vessels in August 2017 to accommodate developments in design technology and to improve both safety and environmental protection.

By updating its rules and guidelines, the classification society aimed to ensure that new designs and technologies will be safely and efficiently implemented on BV-classed vessels.

Its latest rules revision for tugs “demonstrates how BV is keeping up with towing industry requirements to address the specific features of novel designs,” said BV global market leader for tugs and offshore support vessels Eva Peño.

BV’s new rules include service notations for escort tugs that indicate the design values of bollard pull, steering/braking force and speed. They also include notations for restricted operations that are applied to harbour tugs and coastal tugs.

She explained to Tug Technology & Business how the revised rules enable BV to class tugs with different towage and engineroom technology. For example, BV has classed two Carrousel Rave tugs built for Multraship Towage & Salvage by Damen Shipyards in 2017. These tugs – Multratug 32 and Multratug 33 – each have a carrousel towing system that enables the towing line to swivel 360˚ around the tug.

In this case, Ms Peño said new rules enable specific issues to be addressed, including “helping to ensure that the tugs’ escorting performance targets are achievable while remaining within the safety limits”. This means BV is helping to protect the environment by avoiding towage accidents, she said.

BV is helping the towage industry reduce its environmental footprint by turning to alternative fuels, such as liquefied natural gas (LNG). This is increasingly important as international regulations become ever-more stringent, said Ms Peño, so the society has developed class rules and risk management tools that enable the safe use of clean energy sources and hybrid-electric propulsion systems.

While the advantages of LNG as a fuel include reductions in SO2, NOx and particulates, there are safety risks that have to be properly addressed. Among these, Ms Peño includes the identification of hazardous areas, storage of tanks and gas handling equipment as the principal risks. She added that BV has the largest share of the classification market for gas fuelled vessels so “we have experience across many ship types, containment systems, bunkering systems and port conditions.”

Safety and emission mitigation measures agreed by IMO and adopted in the IGF Code (International Code of Safety for Ships using Gases or other Low-flashpoint fuels) are fully incorporated in BV rules. This is one reason that has been given for why Østensjø Rederi turned to BV to class three dual-fuelled tugs designed by Robert Allan and built by Astilleros Gondán in Spain in 2017.

Because of their innovative LNG fuel and storage systems, and their design for Arctic operations, Dux, Pax and Audax were named Tug Technology and Business’ Tug of the Year 2017 (Tug Technology & Business, Q4 2017)

“A further example of innovation in eco-friendly propulsion systems is the potential to combine energy storage and energy management systems to provide efficient means to optimise performance across operational modes,” said Ms Peño.

“DC grids allow generators to run at variable speeds depending on the power demand”

Peak power demand can be covered by batteries instead of starting another engine. In addition, “DC grids allow generators to run at variable speeds depending on the power demand” she explained.

“As a result, the system will be able to operate optimally while reducing emissions and fuel consumption,” Ms Peño said, adding that a further benefit is that comfort on board tugs is improved due to a reduction in noise and vibration levels.

BV introduced the Electric-Hybrid notation in 2017 to addresses the complexity of these systems. It defines “requirements for storage, power distribution, control and instrumentation and the tests that must be carried out” she said. Based on these new rules, an approval in principle was granted to Wärtsilä for its HYTug hybrid tug design in 2017 (Tug Technology & Business, Q3 2017).

A digital future

Ms Peño expects the future of tug design and operations will be driven by the maritime industry’s digital transformation, with increased use of computerised systems and smart fleet management. She expects connected vessels that are equipped with smart sensors “will enable inspections and maintenance based on continuous condition monitoring instead of inspection at fixed intervals.”

BV introduced a planned maintenance survey system as a result of this drive. It prevents the “too soon, too late risks of the traditional preventive approach and reduces the consequential additional costs due to downtime and unplanned maintenance” said Ms Peño. Increased connectivity means tug operators need to address the associated cyber risks by improving security, she added.

“Reduces the consequential additional costs due to downtime and unplanned maintenance”

To manage these risks, BV is able to identify, analyse, and assess threats and certify that the appropriate mitigation measures have been implemented to ensure a safe transfer of data between vessels and onshore support centres.

As a part of the digital transformation, systems on board, including those essential to safety, are increasingly controlled by computerised systems. Ms Peño said that the International Association of Classification Societies (IACS) acknowledged the need for having appropriate requirements to ensure that computerised systems fulfil their intended function at the required level of reliability and dependability. This was accomplished through IACS Unified Requirement E22 for ship computerised systems.

BV has fully implemented these requirements in its rules and added new notations, such as HWIL (Hardware in the Loop), “to provide a comprehensive framework to safely and cost efficiently testing of control systems in a simulated environment,” she explained.

An example of the offshore vessel sector moving towards digitalisation is the strategic partnership agreement between BV and Bourbon Offshore, which was signed in January 2018. The aim of this smart shipping programme is to develop and deploy automation and real-time fleet monitoring applications, said Ms Peño. This is “to optimise the safety and reliability of vessel operations and reduce operating expenditure.”

Ms Peño expects that expansion of computerised control systems and increasing levels of connectivity is pushing shipping towards operating autonomous vessels, including tugs. BV published guidelines for autonomous shipping in December 2017 to support and assist shipyards and owners to enhance the autonomy of vessels.

It is probable that autonomous tugs will be developed in the future. “Tugs are a vessel type whose function, operational parameters and cost base may be well suited to autonomous operations,” said Ms Peño. “At BV we are ready to take it to the next level.”


Snapshot CV: Eva Peño

Eva Peño is the global market leader for tugs and offshore support vessels at Bureau Veritas. She is a member of the commercial department team and leads its international business development activities. She is driving the implementation of the key account strategy and steering development of new services and standards.

Ms Peño joined Bureau Veritas in 2001 after obtaining a degree in nuclear technology from the Escuela Técnica Superior de Ingenieros Navales in Madrid, Spain. Since then, she has held various technical and project management positions in Madrid and Paris.

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