Why Has the Medium-Speed Diesel Become Competitive in Marine Propulsion?

Since 1965, the market for propulsion plants for large merchant vessels has shown an increasing trend towards medium-speed geared plants. An economic analysis determines the reasons why the medium-speed engine can compete with the slow-running, direct-propulsion, two-stroke engine. The various influences on the types of cost are examined and the cost parameter range within which the medium-speed geared plant is competitive will be marked out. An optimization analysis clarifies the cost advantages that will be provided by tomorrow's still larger medium-speed four-stroke diesels.