The top 4 levers for improving vessel performance
Shipping companies have a myriad of options to improve vessel performance and reduce energy consumption. Which ones are the most important? Here we take a look into our data and fleet performance projects across the globe to find out.
1. Speed and speed management
Speed has the highest impact on fuel consumption, as everybody knows the exponential relationship between the two. While average speeds have been decreasing for some years now across all ship segments, speed variability has not. Vessels very often sail 3-5 knots less or more than their average speed on a voyage or over a period of time on similar trades. The periods with high speed lead to significant surplus consumption that the periods with lower speed cannot compensate for. Speed loitering (starting fast and then slow down), no proper weather routing, varying arrival information are typical causes which can be improved. We can often find 15-20% of saving potential here.
2. Hull & propeller degradation
The underwater hull adds resistance over time due to fouling. As the effect is not so easy to measure, the effect of hull degradation is often overlooked. Traditionally shipping has relied on visual inspections, which only makes sense if the vessel is empty. Today, however, the added resistance can be computed in a reliable manner (due to measurement challenges with thrust meters you cannot separate hull and propeller degradation). It is also important to add that slip is not an appropriate measure. Higher levels of hull degradation then trigger hull & propeller cleaning decisions or a different type of coating when next in the dry-dock. Doing this in the correct manner very often saves 10-15% in fuel consumption.
3. Main Engine degradation
The third lever is not allowing the main engine ( incl. surrounding systems like turbo charger), to degrade and to keep your SFOC close to the shop test baseline. As this is a standard task for the engineers onboard and the technical superintendents onshore, it is surprising that degradation is often not recognized early enough. Small increases in the SFOC have a big impact. A regular look into deviations of SFOC, TC speed, exhaust gas temperature, scavenge air pressure, Pmax and Pcomb helps. 5-10% of fuel can be saved on many of the vessels we have looked at.
4. Trim and draft
The more vessels are hydrodynamically “optimised”, i.e. have distinct underwater hull shapes, such as bulbous bow or wide transoms, and the more vessels are sailing away from their design conditions (design speed and draft) the more they can benefit from working with trim and draft optimisation in their operations. This has been known for many years and has been proven across all vessel classes. Still, only a fraction of vessels work actively with trim and draft optimisation and we are monitoring vessels that leave up to 10% saving potential untouched by ignoring the trim advice given. Trim also falls into our 5-10% saving potential range.
Dr. Thilo Dückert, Product Manager, Fleet Performance Management