Fuel is Only Part of the Strategy on the Path to Decarbonization

Shipping’s decarbonization discussion has centred on fuel choice for good reason. Policies such as FuelEU Maritime and the EU Emissions Trading System, combined with sustained pressure on bunker costs, have made fuel strategy a central commercial consideration. Decisions around LNG, methanol, biofuels and other alternatives will continue to shape vessel design, infrastructure investment and long-term compliance for years to come. However, while fuel decisions may influence how a vessel should perform, they do not, on their own, guarantee that those outcomes are realized in day-to-day operation. That depends on how consistently the wider system is maintained and managed over time.

Wärtsilä’s recently published ‘At the Helm’ report, based on a survey of 225 maritime leaders, highlights the operational pressures behind that challenge. It found that 68% of respondents believe prevailing unpredictability makes prioritization a constant concern, while 42% say balancing investment costs against return expectations is a persistent issue. Together, these pressures shape how operators manage the fleet they have today, not just the fleet they are planning for the future. And it is in the existing fleet where the gap between fuel strategy and operational reality is most visible.

The regulatory landscape makes that gap increasingly expensive. FuelEU Maritime sets limits on well-to-wake GHG intensity starting with a 2% reduction from 2025, rising to 6% by 2030 and tightening progressively towards 2050. The CII, meanwhile, rates vessels annually from A to E, with weaker ratings affecting charter rates and triggering corrective action plans. Under EU ETS, at an allowance price of €90 per tonne, operators can save around €270 for every tonne of fuel saved. Against this backdrop, unexplained performance drift is not just a technical issue. It carries a direct and calculable financial consequence.

Performance drift rarely appears suddenly. It develops over time through individually reasonable decisions made under pressure: a component selected for availability rather than verified compatibility, maintenance carried out to a standard that was sufficient at the time, or calibration that is not revisited as operating conditions change. These decisions are often entirely rational at the time, made under operational and commercial constraint. Vessels that appear similar on paper begin to show differences in fuel consumption and reliability. No single decision explains this. The cumulative effect of small variations over time does.

Many of these decisions are also taken at different points within the organisation, often with limited visibility across the full system. Procurement, technical and operational priorities do not always align in real time, and the combined effect may only become clear later, once performance begins to diverge.

A routine purchasing decision made under pressure follows a familiar pattern. A vessel needs a component. Something is available that appears to match the specification. It is fitted, the vessel keeps operating, and the issue feels resolved. What is harder to see is that a part that installs cleanly can still behave differently from the original over years of operation. Differences in tolerances, materials and wear characteristics affect fuel consumption and reliability in ways that only become visible later – often when the vessel is already underperforming against the benchmarks it is now commercially required to meet.

An individual component also does not operate in isolation. Its behaviour is shaped by how it interacts with the wider propulsion and energy system, and those interactions can influence performance in ways that are not immediately apparent. As vessels become more complex, combining propulsion, fuel, automation and digital systems, the margin for inconsistency narrows further.

These decisions are often made with a focus on availability and cost at the point of purchase. The longer-term performance implications are less visible at that stage, but can become more significant over time.

The At the Helm report is clear that compliance has shifted from a cost to a source of competitive advantage: smart investments made at the right time not only help avoid financial penalties, but also position fleets for premium charter rates and access to green financing. Poor component choices can quietly undermine that advantage.

Traceability is also more important than it is often given credit for. Knowing what has been fitted, when, and to what specification provides the basis for understanding system performance. It also supports the documentation required for IMO and EU reporting. Without this visibility, identifying the source of performance deviation becomes more difficult, particularly once a vessel is operating outside expected parameters.

Maintenance strategies are evolving in response. For many operators, maintenance is no longer viewed only as a periodic technical requirement, but as part of a broader commercial approach. Proactive methods, including condition monitoring and system diagnostics, can identify issues earlier and reduce unplanned interventions. Access to operational data has increased significantly across the industry. The value lies not only in having that data, but in acting on it consistently over time to maintain performance.

More consistent maintenance supports better cost predictability and operational stability.

Service agreements are one route to achieving this. When structured effectively, they combine planned and predictive maintenance, parts availability, remote operational support, technical expertise and performance monitoring within a defined framework. The planning window this creates allows operators to schedule resources, tools and personnel more effectively. It also helps maintain continuity in component history and documentation, supporting both operational reliability and compliance requirements.

Much of the global fleet will need to operate for longer while fuel pathways and regulation continue to evolve. For many operators, the immediate priority is maintaining the performance of existing assets rather than fleet renewal. This brings fuel strategy and operational decisions closer together, particularly in areas such as maintenance, system integration and component selection.

The industry will continue to debate fuels. However, a vessel’s CII rating, EU ETS exposure and ability to meet FuelEU Maritime requirements are all influenced by how consistently it is maintained and how its systems perform over time.

This is not a new challenge. What has changed is the environment around it. As regulatory pressure increases and performance margins narrow, small variations in system behaviour carry greater commercial weight.

Spare parts decisions may not feature prominently in fleet strategy discussions, but their impact becomes clearer when performance or compliance comes into question. In many cases, outcomes reflect not a single decision, but the cumulative effect of smaller choices made over time, often without a clear point at which performance begins to drift.

For operators, the focus becomes less on individual components and more on how consistently the wider system performs across the vessel’s lifecycle. In a more data-driven and regulated industry, that consistency, and the ability to explain it, becomes increasingly important.