Every extra mile and every idle hour in port is a ‘carbon tax’ that a vessel pays with its annual rating. While the industry focuses on engine efficiency, the real battle for the CII rating is won or lost in the chartering office, where the ship’s trajectory is decided long before the engine starts, writes Natalia Liashenko, the CEO and founder of Marine Solver.
Decarbonisation in shipping is currently evolving along two main paths: the technological (new fuels and designs) and the operational (voyage execution). While both are essential, they often miss a critical third layer where the actual environmental fate of a vessel is decided: the commercial decision-making layer.
In the era of CII ratings and EU ETS, we are seeing a growing gap between how a voyage is executed and how a year is planned. This gap creates what I call the ‘geographical trap’ – a situation where even the most fuel-efficient vessel cannot escape a poor rating due to the structural constraints of its employment.
The fairway concept
In navigation, a fairway defines the safe water for a vessel. In the commercial world, every chartering decision – selecting a cargo, a route, or a delivery window – creates a commercial fairway.
Once a vessel is committed to a specific cargo or region, the boundaries of its environmental performance are largely fixed. You can optimise speed and fuel consumption during the voyage (the ‘steering’), but if the course itself leads into a high-emission zone or a low-efficiency trade pattern, flawless execution will not save the annual rating.
The geographical trap
Our data modelling reveals a stark reality: environmental performance is not just about how you sail, but where you are sent.
We often see cases where one vessel achieves, for example, a C rating on a specific trade route, while an identical sister ship cannot rise above an E simply because it is operating in a different decision space. If the available cargo pool in a region forces long ballast legs or frequent port delays, the vessel is effectively in a geographical trap. Within this trap, traditional operational optimisation reaches its limit. The problem isn’t in the engine room or on the bridge; it is in the original selection of the voyage chain.
The disconnect of horizons
The root of the problem lies in the mismatch of time horizons. Commercial teams typically operate on a voyage-by-voyage basis. However, decarbonisation metrics like CII are accumulated annually. This creates a computational challenge: the sheer number of variables – cargo combinations, port congestion, and bunker prices – exceeds the capacity of traditional spreadsheet planning.
When decisions are made in isolation, without visibility of the annual trajectory, the vessel’s rating becomes a byproduct of chance rather than a result of strategy. By the time the mid-year report arrives, it is often too late to correct the course. The fairway has already led the vessel into a dead end.
From isolated steps to continuous planning
To break out of these traps, the industry needs to move beyond discrete voyage optimisation toward continuous situational modelling.
Decarbonisation is not an additional constraint; it is a new dimension of commercial quality. Managing it requires the ability to rapidly explore the entire decision space – evaluating not just the next immediate trip, but the sequence of moves that follow.
This is where advanced decision support systems become essential, as they can minimise total time and distance across an entire voyage chain in ways human intuition cannot.
Even with partial market visibility, it is possible to model exit points from low-efficiency regions and identify chains of cargoes that align with the required annual CO2 trajectory.
Conclusion
The boundary of competitive advantage in shipping has shifted. It no longer lies solely in how well a vessel is operated, but in the mathematical rigour applied to where it is positioned.
Flawless steering is vital, but it cannot compensate for a wrong course. The future belongs to those who use advanced digital modelling to see the fairway before they enter it, ensuring that every commercial commitment serves the long-term environmental and financial health of the fleet.
