7 June 2019

For Damen, the IMO Tier III NOX regulations represent a significant move towards cleaner and greener operations. Improving air quality in harbours is an important issue, especially when taking their proximity to urban locations into account. Damen has a large number of tug-owning clients in the North Sea and Baltic Sea Emission Control Areas. Therefore the significance of IMO Tier III cannot be overestimated.

“We started brainstorming sessions on this subject back in 2012,” says Jeffrey Jacobs, Technical Manager Tugs. “Looking for the best NOx emission reduction systems on the market, we had technical challenges and space was one of the limiting factors. Therefore we needed to combine an exhaust emission reduction system with our engine silencers. To support our Damen philosophy by giving our customers the opportunity to choose a green product with short delivery times, or deciding to easily upgrade their vessels when needed, we set another requirement which was difficult to meet.

“Being able to meet these tough requirements and provide our clients with the standard, reliable, robust and Damen-quality products, suitable for multiple marine diesel engines, we decided to develop our own Damen after-treatment systems.”

damen rsd tug 2513 'bis viridis' recent delivery

80% reductions

With this decision a Damen After-Treatment Team was established. Its first assignment was to develop a NOX reduction system for the new generation of Tugs: the ASD Tug 3212ASD Tug 2813ASD Tug 2811ASD Tug 2312 and RSD Tug 2513. This involved partnering with after-treatment company Emigreen, he adds. “This partnership joins twenty years of knowledge, R&D and experience of after-treatment systems with 90 years of experience of designing and building vessels.”

The cooperation with Emigreen was fruitful, leading to an in-house designed and developed system which has been tested on multiple test benches. “The resulting Damen Marine NOX reduction system is a fully certified and type approved IMO Tier III system, reducing NOX emissions by 80% compared with IMO Tier II requirements.”

Plug and play

For owners of Damen’s new generation of tugs wanting to switch to IMO Tier III, the process will be straightforward.

“You can compare it to what we have been doing for years with firefighting systems. We prepare the vessel as much as possible and then can install the optional equipment within a matter of weeks – a plug and play technique.”

Damen’s extensive preparations for NOX regulations have paid off: “We are showing the maritime market that we are ready for this sustainable change. The first projects have been successfully developed, tested and delivered to our customers.” The Damen After-Treatment Team is currently expanding its product portfolio to provide the numerous Damen Business Units with the best technical solutions for NOX reduction systems.

These can even be combined with soot reduction technology to comply with the new Euro Stage V requirements. “These are fit-for-purpose,” concludes Jeffrey. “And take into account the operational profile and specific requirements of the variety of vessels, while keeping our standard product approach.”

Explained IMO Tier III

The International Maritime Organization’s regulations regarding nitrogen oxide emissions have got steadily stricter over the last two decades. This started with the so-called IMO Tier 1 controls in 2000, and continued with IMO Tier II in 2011. IMO Tier III entered force in 2016, but only in North American and US Caribbean waters. For the European market, Tier III regulations will come into effect in the North Sea and Baltic Sea Emission Control Areas from 1st January 2021. This means that all vessels with an engine output greater than 130 kilowatts, with a keel-laying date after 2016 for US waters and 2021 for North Sea and Baltic Sea waters entering these areas must comply with IMO Tier III regulations.

Explained NOX reduction

The Damen Marine NOX reduction system is an advanced active emissions control system using SCR (selective catalytic reduction) technology for NOX reductions up to emissions standards according to IMO Tier III, suitable for marine diesel engines and fuels. It has been designed and optimised for the specific sailing profile of a vessel, and is able to operate on both high and low loads in ambient conditions from -30⁰C up to 45⁰C. Its robust design is suitable for high sulphur fuels (DMA ISO 8217:2017) capable of using both automotive (AUS32) and marine quality urea (AUS40). Combined with 45dB(A) silencers, the system limits the emissions of NOX and noise, thus contributing to a healthier and more sustainable environment.


ASD Tug 3212
ASD Tug 2813
ASD Tug 2811
ASD Tug 2312
RSD Tug 2513


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