PROPULSION ENGINES Global engine manufacturers continue to focus on compliance with the tightened limits for emissions. So far the industry has succeeded in meeting IMO Tier II requirements, in effect since the beginning of 2011, with in-engine measures. However, a major technological leap is now needed to comply with IMO Tier III, which will enter into force in 2016. Both two-stroke engines and after-treatment systems for exhaust gas, such as SCR and EGR, will be integrable in specific propulsion configurations. For this purpose, methods or systems for water injection, exhaust gas recirculation and catalytic after-treatment are being developed. Furthermore, the use of LNG as fuel is gaining more significance. So in addition to dual-fuel four-stroke engines, which have been available on the market for some time already, the engine range has been extended by dual-fuel two-stroke engines. The following table gives an overview of the diesel engine units for maritime propulsion applications currently available on the global market.