Weather routing

The weather (wind and waves) will together with ocean currents influence the power needed to propel a ship at a given speed over ground. Therefore, it is important to take these factors into consideration when planning a voyage and to try to minimize the negative influence.

Applicability and assumptions

The longer the voyages are the more route choice flexibility the ship has in order to avoid unwanted weather conditions. Also longer voyages most often include time spent in unsheltered waters where the influence from weather is making weather routing important. Therefore, the biggest potential could be realized in intercontinental trades and for larger ships.

Ships’ routeing, source: IMO

All ships at all ages can potentially install the system, and therefore it is assumed that the entire fleet can install the measure. However, for existing ships, some ship segments (e.g. large container and ro-ro) have to a certain degree already implemented weather routing and, therefore, have a lower potential for fuel consumption reduction. This is also assumed to be the case for new ships coming into service in this period.

The choice of most fuel efficient route must be balanced against the safest route and quickest route.

In order to improve the weather routing a new system will have to be installed on board all ships. This system is assumed not to become standard in the future and will come at a premium for the time period studied.

The benefit from the measure will come in terms of reduced fuel consumption due to reduced resistance from wave and wind. There might also be a benefit from less fatigue and weather damages.

Cost of implementation

The system is estimated to cost $15,000 (USD) per ship to install and in addition an annual subscription of $3,000 (USD) per ship is needed to keep the software up to date and get the latest weather information.

Reduction potential

The potential has been assessed to between 0% to 5% on main engine fuel consumption dependent on ship size and type and the typical trade for the different ship segments.

Other References

1. IMO / Ships’ routeing
2. IMO resolution A.893(21) / Guidelines for voyage planning
3. IMO Train the Trainer (TTT) / Course on Energy Efficient Ship Operation, Module 3 – From Management to Operation
4. Air pollution and energy efficiency / IMO energy efficiency appraisal tool