SEA: The ratings are defined by the Superior design characteristics vs. the benchmark e.g. lower engine capacity installed vs. peers (as characterized in the benchmark).

SEA: The bands around the curve describe how leaders in their respective segments can be differentiated from the crowd. The segment separations are so to speak the ‘hurdle rates’ for each ship to enter a better-performing peer group.

SEA: For these ratings, the yacht must have superior design characteristics versus the benchmark, for example lower engine capacity installed compared with peers (as characterized in the benchmark).

SEA: As the structure of the underlying data has been extensively vetted – and there are indications that there is a high likelihood that the shape is representative of a wider market – an individual rated ship would then receive an assessment accordingly.

SEA: There are several reasons. First of all, a yacht follows significantly volatile and unique operating profiles unlike a cargo ship, for which a cruise speed is explicitly defined, certified and controlled in the operations phase. Secondly, calculating a cruise speed and a consistent level of consumption is not feasible due to non-linear physical relationships. Thirdly, if cruise speed is reported for a yacht, this data point is not explicitly defined (and implies varying MCRs), destroying a like-for-like comparison between ships. Fourthly, coherent data covering service/ cruise speed and consistent consumption is not available. This would require collecting sea trial information. It could potentially be done at a later stage, but climate change is so pressing that we cannot postpone the debate. We have to act based on our findings.

SEA: We started from the objective to amend the IMO EEDI framework to plug into current debates as much as possible, rather than reinvent the wheel and launch an entirely new methodology, which takes time to establish. As was done by the IMO in relation to commercial ships, we asked ourselves what ‘transport work’ really is and how it relates to ship design. This is ‘guest space moved’ (similar to DWT moved in the case of cargo ships). By introducing the guest into the equation, each guest can then, with a simple calculation, relate an emissions profile to the individual’s carbon footprint. If normalization were only done for GT (also a possibility), the formula would be more abstract. ‘Guest space moved’ exhibits a higher statistical relevance than GT only.

SEA: We have calculated the Froude number, which describes the resistance of an object moving through water. In order to ensure that only displacement and semi-displacement hulls are in the sample, we have limited the sample data to ships with a Froude number of <= 0.8.

SEA: We have leveraged the IMO definition for fuel consumption (=215 g fuel/kWh), as used for passenger ships, and the IMO carbon fuel factor for diesel, as this is the commonly used fuel in superyachts.

SEA: This would require a) defining the operating conditions of a mix (which might be arbitrary) and b) a consistent definition of speeds with consumption. A non-linear relationship would exist, meaning it could not be easily calculated. Going forward, however, collecting more information on this topic might be an area of investigation.

SEA: This definition is clear and not ambiguous. It is defined as a clear ranking within the total sample. Even if the data set grows over time or characteristics change, the relative definition will remain the same. In effect, it is robust against changes in the underlying data sample. Additionally, it is a modular approach, allowing later extension to other pollutants.

They follow a different design concept. As a consequence, it would not be appropriate to calculate carbon emissions with the same approach as for displacement and semi-displacement hulls.

SEA: There are no plans as of yet to include them in the calculations and benchmarks. YCM’s Belle Classe begins at 40m and yachts of an inferior length are almost exclusively planing hulls. However, we hope that in the sub-40m range the activities of SEA will inspire yacht and engine builders to strive for more energy-efficient designs.

SEA: We started from the observation that to date there has been no reference point for the yachting industry. To introduce one, we decided it would be important to calculate benchmarks and define measurable objectives through the Association, as a collective voice for the industry. Our SMART approach ensures that the index is designed to be specific, measurable, achievable, relevant and time-based.

Regarding the yacht retail sector, we certainly hope that in the long term it will have a positive impact, especially for the shipyards and owners taking part and doing all they can to improve the environmental performance of their vessels, as a result of the implementation of the index and its rating system.