20 Years of Marine Propulsion

摘要

20 years does not seem a long time in marine propulsion. Most of the ships that were new, or recently launched, in 1987 are still afloat today. Like the vast majority of present day ships, they have a single main engine driving a shaft and propeller, either direct or through a reduction gearbox. Outwardly the engines and other major components seem very much the same. But lurking within current engine blocks a great deal has changed. Two words can sum up the last 20 years - emissions and consolidation.