Ships operate in some of the most complex and variable environments of any transport system. Weather conditions, cargo loads, vessel design, routing decisions and operational practices all influence how much fuel a ship consumes on any given voyage. In this insight, we explore why the inherent complexity of ship operations makes it extremely difficult to isolate and verify small efficiency gains. When improvements are measured in single-digit percentages, even minor variations in operating conditions can obscure the true impact of a technology.
Ship performance is inherently complex.
Unlike cars, which operate under relatively stable conditions and are produced in large, standardised series in the thousands or millions, merchant ships are bespoke assets, with even a large class rarely exceeding 20 sister vessels.
Furthermore, ships are moving between two fluids (air and water), which introduces specific physical characteristics such as waves. Cargo load and speed profiles also vary from voyage to voyage, and in addition, ships operate largely out of sight for days or weeks at a time, with limited real-time reporting.
A vessel departs with its crew, sends a single daily report, and arrives at its next port under the captain’s judgment and experience. These factors make it difficult to measure true efficiency improvements, especially when targeting gains of just 5-10%.
According to Vincent Joly, SmartShip Manager at Bureau Veritas, performance measurement is shaped by three components: ship design, external conditions, and operations. Measuring these changes is critical but assessing the impact of one modification without variation of another component is simply unrealistic.
Measurement challenges stem from both known unknowns and unknown unknowns. Known unknowns are factors that are understood but still challenging to model accurately.
While physics and hydrodynamics can model each factor individually, a universal equation that combines all of them in real-world conditions does not exist. This means that predicting a ship’s true power demand and therefore fuel consumption is not a straightforward calculation because it is influenced by dynamic, interrelated factors that can’t be captured in one neat formula.
Similarly, while weather-related resistance can be partially modelled, hull fouling, responsible for up to 40% of total drag according to Joly, cannot be measured directly and must instead be inferred.
Unknown unknowns are even more problematic. These are untracked or unmodelled influences such as variations in crew behaviour, actual route versus the planned route, forecast weather versus actual, fuel quality, localised biofouling, hull or propeller deformations, engine maintenance, and more.
As a result, validating the savings from digital or physical upgrades becomes a costly and time-consuming process.
Download ‘The 5-10% Illusion’ and explore why the maritime industry’s reliance on unverified efficiency claims is eroding trust, and discover a framework to restore measurement discipline.
