A new future for Vessel Performance assessments

Nobody likes Bad Weather.

Especially charterers, as only during good weather periods charterers receive a warranty on bunker consumption during a voyage. Hence having sufficient Good Weather days is essential to have any warranty on performance. Many voyages, however, have an excess of “bad weather days”, so often no assessment can be made at all.

Besides the need for Good Weather periods, current Charter Party Performance clauses, have more disadvantages:

- Only one data point per day, with averages on speed and consumption over 24 hours with 6-hour interpolations.

- Based on non-objective, manual input of speed and consumption.

- Long discussions on the interpretation of weather limits

But most importantly, the warranties are often only valid for just 2 or 3 speeds, like full- and eco-speed. This limits flexibility for important sailing strategies like just-in-time arrivals, that have the possibility to reduce carbon emissions significantly.

Over the last years, we have worked on a new, better way of establishing performance assessments. Until recently, however, the High Court only accepted the traditional approach. But now, times are changing!

Opening the door to Alternative methods

We’re now seeing a door opening to alternative methods that do not rely on Good Weather samples.

A High Court decision* published this August, states:

“94. The authors of Time Charters suggest that modern means of measuring performance could provide a more finely tuned method, that would not depend on a good weather sample. ...

We have been developing and validating new methods over the years. Through our Digital Twin, a new way of performance assessment is now available.

No more Bad Weather days

The Digital Twin can help to establish normalized vessel performance, allowing Owners and Charterers to make performance assessments on every day of the voyage. A Digital Twin is a digital performance model that can accurately calculate the effect of weather on the performance of a vessel.

For every moment during the voyage, we can now calculate the weather effect, which can be positive (favorable currents for example) and negative (adverse currents, waves, and wind) as displayed below. On a voyage level, we report on the total weather impact for that voyage either on fuel consumption or speed.

Weather impact as calculated by We4Sea's Digital Twin
Weather impact as calculated by the Digital Twin

Based on real-time, accurate, and objective weather data, we can calculate the speed loss (or -gain) every 15 minutes. The overall weather-related speed loss is subtracted from the observed speed, based on satellite data. The result is the Performance Speed: the speed the vessel would make without weather. This can, conservatively, be directly compared to the speed instruction.

We4Sea Digital Twin Performance Speed
The Speed Through Water (in pink) and the Performance Speed (in green)

Any voyage, any time, any vessel

The most interesting result of this method: No more bad weather days. We report on net performance, based on every day of the voyage. That means no data has to be discarded. Hence the full voyage from start to end of the sea passage can be considered.

The other advantage is that by using a pool of weather and position data, any voyage can be assessed. Even historic voyages from recent years can be re-calculated using this method.

Future proof

We believe this technology can have a bright future, as it has the power to align all of the competing interests and incentives of a charter-party relationship.

Not only to increase efficiency, but also in order to meet the IMO’s 2050 mandate to reduce CO2 emissions by 50%.  We basically need to do things differently, and the good news is that the technology is now available!

Interested how its done? Like to assess one of your vessels? Let's talk!

* Eastern Pacific Chartering Inc v Pola Maritime Ltd, 2022 EWHC 2095 10/AUG/2022