Medium-Speed Propulsion Engines
Slower-running, heavier engines for tugs, dredgers, inland cargo vessels and coastal traders that work at high load for long hours.
Features
- Lower mean piston speed gives longer component life at sustained high load, which is what a working vessel needs rather than peak output.
- Higher mass and larger footprint, so the bed, the lifting arrangement and the engine room access all need checking at survey.
- Overhaul is planned by scope rather than by symptom, with a top-end at one interval and liners, pistons and bearings at a multiple of it, which is what makes lifetime cost predictable.
- Usually keel cooled or on a closed freshwater circuit for work in silty water.
- Often driven through a high-reduction gearbox to a large, slow propeller, which is where the efficiency of this arrangement comes from.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Rated power and speed | 600 at 900 | kW at rpm | defines the rating and the gearbox ratio |
| Duty rating | continuous, unrestricted hours | the rating a working vessel is bought on | |
| Dry mass | 3 800 | kg | decides lifting, bed and trim implications |