How do hull condition, weather, fuel-oil system maintenance and propeller blade damage raise fuel consumption, and how can each be best controlled?
Short answer
| Factor | Why fuel goes up | Best control |
|---|---|---|
| Hull condition | Fouling and roughness raise frictional resistance | Anti-fouling or foul-release coating, in-water hull cleaning, performance monitoring |
| Weather | Wind, waves, swell and currents add resistance | Weather routeing, speed and trim management |
| Fuel-oil system | Poor treatment, injectors or timing raise specific fuel consumption | Purifiers, injector overhaul, fuel-pump timing, viscosity control |
| Propeller damage | Damaged or rough blades lower propeller efficiency | Polishing, repair and re-profiling at docking |
- Fuel consumption rises when the ship’s resistance increases or the engine’s combustion efficiency falls.
- Frictional resistance is the largest resistance component at service speed. Even a light slime layer adds several percent.
- The Chief Engineer cannot change the weather, but routeing, speed and trim management minimise its fuel penalty.
- Worn or dripping injectors give poor atomisation and after-burning. Water and cat-fines past the purifiers damage injectors and liners.
- A polished, undamaged propeller is one of the best fuel savers.
- Performance monitoring (shaft power, SFOC, fouling trends) ties it together. Under MARPOL Annex VI, lower consumption also improves the ship’s CII.
Full answer
The full answer explains each point step by step, with the regulations and figures behind it and the discussion from other candidates. It is in the MEO Class I section of the Marine One forum, open to members enrolled for the MEO Class I exam.