DISCOVER Magazine #7

Working with Bureau Veritas to set new tug standards

Published in category: Harbour & Terminal
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Jildert Nauta, senior sales & customer relations manager Bureau Veritas

Jildert Nauta
senior sales & customer relations manager
Bureau Veritas

As a leading innovator in all aspects of shipbuilding, Damen maintains close relationships with the main classification societies, working alongside them to develop new standards and to ensure that its new products meet the necessary requirements before they are brought to market. Damen has been working with Bureau Veritas for many years, most recently on subjects close to the hearts of both organisations; improving the safety and sustainability of tugs as they go about their duties.

Harmonising regulations

One key element of achieving this goal has been that of working towards the harmonisation of worldwide tug standards. With most tugs generally operating in national waters and being below 500 GT, the majority fall outside the scope of the IMO Conventions. The result is that over the years individual flag states and classification societies have developed and implemented their own standards. This has led to a wide variety of regimes with little consistency and so, given the high incidence of girting events and the associated risk of loss of life, there has been an urgent need to develop a harmonised international regulatory framework for towing stability.

“Following discussions with tug designers, builders and operators, we made a commitment to support the towing industry for the development of harmonised safety standards,” says Jildert Nauta at Bureau Veritas. “One of the outcomes was the publication of the Guidance Note: Recommendations for life saving appliances, radio installations and navigation equipment for tugs of less than 500 GT (NI 617). This guideline provides recommendations for statutory requirements deemed applicable for tugs in accordance with their area of operation and takes into account the specific characteristics of these vessels; e.g. the requirement for a rescue boat may be subject to the assessment of the tug’s operational working area, manoeuvrability, size, freeboard and propulsion arrangements”.

Stability

Damen and Bureau Veritas have been working together on improving towing stability, which is crucial for the safety of tug operations. Unexpected events or unintended actions can cause the towline and its load to suddenly shift to one side of the tug. As a consequence, forces are generated which can cause the tug to heel and may ultimately result in capsizing. This occurrence is known as girting.

“Generally speaking, there are two causes for a girting event,” says Jildert. “The first is the case when the tow veers off, for example due to a loss of propulsion or steering on board the tug, with the result that the tug is dragged along sideways. This is called tow-tripping. This is the classic stability issue for tugs, whereby the towline pull versus the drag force of the tug’s hull creates a heeling moment.

“Secondly, as tugs have become more powerful and manoeuvrable to meet the demands for higher bollard pull and greater operational capability, there is a possibility for tugs to overturn as a result of their own propulsive power generating a steering force versus the towline pull. This is called self-tripping, and as this has gained importance it has become a key consideration in the design of modern tugs.”

Within the SafeTug Joint Industry Project (JIP), Bureau Veritas has also led the development of the harmonised safety guidelines, whereby stability has been one of the key items.

Escort operations

A further development in recent decades that has had an impact on tugs’ safety profiles is that of tugs being increasingly engaged in escort operations. There they are used for active steering, braking and otherwise controlling an assisted ship as it moves at speeds typically in the range of six to ten knots. “As high steering forces are characteristic of the normal operation of escort tugs, rather than an accidental situation as occurs with ship-assist tugs,” notes Jildert Nauta, “we have had to ensure that the stability criteria for tugs used in these operations are even more stringent.

To further this cause, Bureau Veritas was offered a platform by the French government to propose harmonised towing and escort stability criteria to the IMO for its planned amendments to Part B of the 2008 IS Code with regard to towing. In accordance with IMO procedures, the entry into force of the new stability regulations will take place on 1 January 2020 (MSC. 415 (97)). Bureau Veritas implemented the requirements in its own classification rules in 2017.

Working with Damen on sustainability solutions

“At Bureau Veritas we know Damen as a ship building company that continually looks ahead,” concludes Jildert, “especially when it comes to technical solutions that are aimed at enhancing sustainability in shipping. Here, Damen often takes the leading position. As Bureau Veritas we are proud to have been able to be a partner in various projects which have introduced new levels of sustainability.
“These include the reduction of NOX from exhaust gases, where we classed the Damen RSD Tug 2513 Bis Viridis, which is equipped with a NOX reduction system that meets the most stringent IMO Tier III requirements. The system was developed by Damen Shipyards and certified by Bureau Veritas for multiple types of marine diesel engines. The NOX reduction system is based on the SCR (selective catalytic reduction) technology using urea as the reducing agent. In order to save space, the SCR has been combined with the 45 dB(A) silencers.

“In close cooperation with Bureau Veritas, Damen also designed an innovative range of tugs powered by natural gas. Developing a modular system that could be placed on a highly powerful and relatively small tugboat where space is a limiting factor and manoeuvrability is a key element to safe operations was a challenging task. However, together with Bureau Veritas and flag state authorities a new regulatory framework was established to make this possible.“

Over the years, Bureau Veritas has classed more than 2,000 Damen vessels and, in 1972, Damen presented Bureau Veritas with a unique model of a Pushy Cat. Over the following years Damen borrowed it back on numerous occasions for events and exhibitions and now, as a gesture of friendship, Bureau Veritas is returning it to its original home. On Tuesday 18th June a small ceremony will take place to hand over the ship model.

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