icon_arrow_down icon_arrow_left icon_arrow_left_large icon_arrow_right icon_arrow_right_large icon_arrow_up icon_bullet_arrow icon_call icon_close icon_facebook icon_googleplus icon_grid_off icon_instagram icon_login icon_mail icon_menu icon_message icon_minus icon_pinterest icon_plus icon_quote_end icon_quote_start icon_refresh icon_search icon_tick_on icon_twitter icon_video_play icon_youtube

Sign up to our mailing list for the latest Boat International & Events news.


Missing your newsletter?

If you’ve unsubscribed by mistake and would like to continue to hear about the latest Boat International & Events news, update your preferences now and let us know which emails you’d like to receive.

No, thanks
4 points that explain the IMO Tier III NOx regulations

4 points that explain the IMO Tier III NOx regulations


What is Tier III of the IMO NOx regulations?

If Kismet was being launched after 2016, she would need to comply with the regulations.


Put forward by the UN’s International Maritime Organisation, Tier III of the IMO NOx regulations aims to reduce nitrogen oxide emissions (NOx) by approximately 70 per cent compared with the current Tier II standards.

The regulations apply to vessels in North America, the US Caribbean, the Baltic Sea, the North Sea, and all future NOx Emission Control Areas: any boat that might pass through must comply, which basically means all must adopt these regulations.

Sponsored Listings

What does this mean for superyachts?

Forever One is over 500GT but avoids the new regulations because she was launched before they come into effect.


On January 1 2016 IMO Tier III comes into force and it will impact every large yacht with a gross tonnage over 500 and diesel engines more than 130kW.

“If the keel is laid after January 2016, the yacht has to comply to Tier III,” explains James Roy, yacht design director at naval architecture firm BMT Nigel Gee. “What this realistically means is that any big boat being designed right now will be subject to it.”

By 2021, yachts under 500GT but over 24m LOA will be required to meet the Tier III regulations as well.

Sponsored Listings

How do you cut emissions?

Eco-friendly Grace E features diesel-electric power, but what might be needed for yachts of the future to comply with the new regulations?

Grace E

While an obvious benefit to the environment, these standards are a challenge for yacht builders, designers and engine manufacturers.

The technology being used to reduce NOx emissions is called a Selective Catalytic Reduction (SCR) unit. It uses a diesel exhaust fluid called urea that that acts as a reductant – when it reacts with NOx it converts pollutants into natural elements such as nitrogen, water and minuscule amounts of CO2.

The SCR units are big and heavy, taking up valuable engine room space and weight. There also needs to be a tank for the urea, a material that’s not widely available in the world’s ports.

Pieter van der Linden, mechanical engineering department manager of Heesen Yachts, says it’s best to think of the new equipment as a necessity rather than a burden. “It’s part of a total yacht now, same as the engine,” he says.

The bad news is there is no single solution for reducing NOx emissions in yachts. The current cure involves a number of parties – engine manufacturer, exhaust company, exhaust after-treatment firm – but most builders will want to deal with as few people as possible.

The good news is this lack of uniformity paves the way for creativity, because after-treatment units can be made in different shapes and customised to a point. Volvo is adapting its decade of on-road SCR experience to the marine environment, with an added focus on fuel efficiency, which will in turn lead to smaller fuel tanks and overall weight savings.

Sponsored Listings
Loading content...
Upgrade your account
Your account at BOAT International doesn't include a BOAT Pro subscription. Please subscribe to BOAT Pro in order to unlock this content.
Subscribe More about BOAT Pro