# Ship propulsion

Marine diesel and LNG engines, wind-assisted ships and nuclear vessels.

Source page: https://www.materialinsights.org/energy/e_marine/

Conversion and use · Transport systems · No. 115

- Conversion and use
 Conversion and use · Transport systems · Foundation · Energy

The biggest ship engines are several storeys tall and among the most efficient heat engines ever built, topping 50%.

Chart: Illustration: Ship propulsion

##### Where it comes from

Chart: Map of where it comes from

Large ships use slow two-stroke diesels coupled straight to the propeller; big slow cylinders lose little heat. Heavy fuel oil supplied 79% of international shipping energy in 2018.

##### Three things to know

1. Only about 30% of a ship's fuel energy ends up pushing the hull, after engine and propeller losses.
2. A ship over 20 years old burns about 2.4 times as much fuel per container as one under five.
3. LNG engines that premix gas with air let about 6.4% of methane escape unburned, against 3.1-3.5% assumed in rules.

##### The journey

1. 1 **Bunker fuel**Heavy fuel oil, marine diesel or LNG
2. 2 **Two-stroke engine**Huge slow cylinders turn the shaft directly
3. 3 **Propeller**Bronze blades turn torque into thrust
4. 4 **Hull**Thrust fights water friction, waves and wind
5. 5 **Cargo moved**Containers, ore and oil across oceans
 Covered in [Muscles, wood, water and wind: energy before fossil fuelsEnergy](https://www.materialinsights.org/learn/energy/energy-before-fossil-fuels/)

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_marine/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_marine/correlation/index.md)
- [Science and limits](https://www.materialinsights.org/energy/e_marine/science/index.md)
- [Value chain](https://www.materialinsights.org/energy/e_marine/valuechain/index.md)
- [Unit economics](https://www.materialinsights.org/energy/e_marine/economics/index.md)
- [Engineering methods](https://www.materialinsights.org/energy/e_marine/methods/index.md)
- [Equipment and suppliers](https://www.materialinsights.org/energy/e_marine/equipment/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_marine/links/index.md)