Improve vessel energy efficiency at the right time

Whether your vessel is in operation, approaching maintenance, or heading to dry dock, different actions can improve vessel performance in different ways.

Energy efficiency is not one decision. What makes sense depends on whether your vessel is operating today, approaching maintenance, heading to dry dock, or still being designed. Wärtsilä helps you identify the right efficiency actions for your vessel’s current situation - from operational optimisation to retrofits, upgrades and newbuild design choices.

At a glance

Best for: Ship owners and operators looking to reduce fuel use, emissions and operating cost
Core question: What can you do now — and what will wait?
Use this page to: Identify the right actions that improve your vessel performance based on your decision window
Applies to: Vessels in operation, planned maintenance, dry dock and newbuild projects

Not sure where to start?

Use the interactive guide to identify the vessel-efficiency opportunities that would be most relevant to your current situation.

The cost of waiting is often higher than expected

Many efficiency improvements are time-sensitive. Waiting does not only delay potential fuel savings. It can also mean missing maintenance windows, dry-dock opportunities and design decisions that may not become available again for years.

The earlier you identify the right opportunity, the more flexibility you have to plan investments, improve performance and maximise long-term returns.

Continuing fuel losses

Fuel inefficiencies continue to affect operating costs every voyage.

Missed maintenance opportunities

Some improvements are easiest and most economical to implement during planned service activities.

Missed dry-dock opportunities

Combining upgrades during dry dock can improve economics and reduce disruption.

Shorter time to recover investment

The later improvements are implemented, the less operating time remains to realise the benefits.

Choose your situation – and discover what you can do next

Right now (In operation)

Best for:

Lowering fuel costs with minimal disruption

Typical challenges:

To come Fuel consumption is higher than expected for the vessel's operating profile.
Performance differences between vessels or voyages are not fully understood.
Opportunities to improve efficiency need to be identified without disrupting operations.

Consider:

Optimise vessel routing and voyage planning
Adjust routes and speed profiles based on real operating conditions to reduce fuel consumption.
Use weather and current data for route optimisation.
Incorporate weather, currents, and operational patterns into daily decision-making.
Use onboard monitoring and optimisation tools
Gain visibility into how your vessel is actually performing across voyages and conditions.
Refine propulsion control for better efficiency
Fine-tune how engines and onboard systems operate to improve efficiency without physical changes.

Why now?

These actions improve efficiency immediately and help identify where larger improvements could deliver value later. Performance monitoring and improved vessel performance management can reveal other opportunities for improvement.

You don’t need downtime or CAPEX to start improving performance.

Typical results:

Up to 6% better fuel efficiency through voyage optimisation and fleet performance management.

Around 5% improved route efficiency using smarter routing and operational decision-making.

Greater visibility into performance improvement opportunities.

Operational insights often reveal opportunities best addressed during your next maintenance stop.

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Next maintenance stop

Best for:

Protecting performance and recovering lost performance

Typical challenges

To come Engine or vessel performance has gradually declined over time.
Maintenance activities are already planned, creating an opportunity to improve efficiency at the same time.
The root causes of increased fuel consumption or reduced performance are not fully understood.

Consider:

Structured maintenance
Predictive maintenance
Engine performance upgrades
Engine derating where appropriate

Why here?

Maintenance windows create opportunities to improve efficiency and reliability without creating additional downtime.

Maintenance windows unlock targeted performance improvements.

Follow structured maintenance practices to reduce fuel use
Adopt predictive maintenance to identify efficiency losses
Perform engine performance upgrades
Derate engines where applicable for efficiency gains

Typical outcomes:

Recovered vessel and engine performance through targeted maintenance and efficiency improvements.
Reduced operational risk and improved reliability by identifying and addressing developing issues earlier.
A stronger basis for future upgrade decisions through improved condition visibility and performance insight.
More predictable maintenance planning and fewer unexpected interruptions.

Many efficiency improvements prepared during maintenance are fully realised during dry dock upgrades.

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Next dry dock

Best for:

Step-change efficiency improvements and long-term fuel savings

Typical challenges:

To come The vessel is approaching dry dock, but the most valuable combination of efficiency upgrades has not yet been identified.
Fuel consumption and emissions performance suggest that larger efficiency improvements should be evaluated.
Several upgrade options are available, but their long-term impact and business case are uncertain.

Consider:

Propeller optimisation
Energy-saving technology
Nozzle improvements
CFD-supported optimisation

Why here?

Dry dock is often the highest-value efficiency investment window available during a vessel's operating life. It creates access to propulsion, hydrodynamic and structural improvements that can continue generating fuel savings for years.

This is also when it is often the most practical time to combine multiple efficiency improvements into a single investment decision.

Dry dock is where the biggest efficiency gains become possible

Install a pre-swirl stator such as EnergoFlow
Add an energy-saving propeller cap such as EnergoProFin
Install a redesigned propeller
Integrate propeller and rudder systems (EnergoPac)
Install a high-performance nozzle
Optimise thrusters and tunnel grids (Elogrid)
Apply CFD-based optimisation and design refinements

Typical results

Many vessel owners achieve their largest fuel-efficiency gains through carefully selected dry-dock upgrades rather than day-to-day operational changes alone.

Up to 10% fuel-efficiency improvement
Through hydrodynamic optimisation and energy-saving technologies.

Efficiency gains visible within the next operating cycle
Dry-dock upgrades can deliver measurable performance improvements soon after returning to service

Built around payback and long-term value
The right combination of upgrades can create a strong business case while forming the foundation for future fuel savings.

Combining these upgrades with operational optimisation maximises long-term efficiency gains.

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Newbuild

What you can do to ensure that your newbuild is as energy efficient as possible

Best for:

Long-term efficiency and flexibility

Consider:

Hull and propulsion optimisation
New rudder concept
Hybrid solutions
Shore power readiness
Shaft generators
Wind-assisted propulsion

Why here?

Some of the most valuable efficiency decisions are easiest and least costly to make in the vessel design phase, before the vessel enters service.

Fuel costs remain one of the largest operating expenses over a vessel's lifetime.
Regulatory requirements continue to increase the importance of efficiency and emissions performance.
Lost efficiency often becomes lost margin throughout the vessel's operating life.
Missed design-stage opportunities can be difficult or costly to recover later.

The earlier efficiency is considered, the greater the long-term impact.

Benefits from thinking beyond individual technologies:

A well-designed vessel can deliver benefits far beyond any single efficiency measure:

Better operational performance from day one, bringing immediate OPEX savings
Continuous performance monitoring to identify ways to save fuel
Greater flexibility for future upgrades and retrofits for maintaining compliance and for even better efficiency
Stronger long-term competitiveness for the new vessel

How to choose the right action to take

Fuel-saving technologies, maintenance activities, operational improvements and vessel upgrades can all contribute to better energy efficiency. The difficult part is deciding which actions should happen now and which should wait for the right implementation window.

The strongest results often come from sequencing improvements correctly rather than attempting to do everything at once.

This is why vessel owners increasingly evaluate energy-efficiency opportunities according to timing, access and expected business impact.

A simple way to think about your options

Your situation	Typical options for efficiency improvements
The vessel is in operation	Operational optimisation and performance monitoring
The next maintenance stop is approaching	Maintenance-driven efficiency improvements and targeted upgrades
The next dry dock is being planned	Propulsion upgrades and energy-saving technologies
Newbuild project	Integrated vessel design and future-ready solutions

Combining the right actions at the right time

Many of the strongest results come from combining actions across multiple opportunity windows. For example:

Operational optimisation can reveal efficiency losses that are later addressed during maintenance.
Maintenance inspections can identify upgrades that are best implemented during dry dock.
Dry-dock improvements can be complemented by ongoing performance monitoring and operational optimisation.
Newbuild decisions can create a stronger foundation for efficiency improvements throughout the vessel lifecycle.

Remember

Not every improvement requires a dry dock.
Not every efficiency challenge can be solved through operational optimisation alone.
The best results usually come from choosing the right action at the right time.
Combining multiple efficiency measures often delivers greater value than implementing them in isolation.

Why timing matters as much as technology

The challenge is rarely a lack of efficiency options. Most vessel owners face the opposite problem: too many possible actions and limited opportunities to implement them.

The question is not only which technology or service could improve performance. The question is which action should come first.

Wärtsilä helps ship owners evaluate opportunities across operation, maintenance, dry dock and newbuild planning, so that improvement decisions can be aligned with operational needs, investment plans and long-term vessel performance goals.

Frequently asked questions about vessel performance

What is the fastest way to reduce fuel consumption without retrofit?

Many vessel owners start with operational improvements because they can often be implemented while the vessel remains in service. Examples include voyage optimisation, weather routing, performance monitoring and other operational measures that help identify and reduce unnecessary fuel consumption. Larger efficiency gains may require maintenance activities, dry-dock upgrades or vessel-design changes.

Which energy-efficiency actions can be implemented during operation?

Some energy-efficiency improvements can be implemented without waiting for maintenance or dry dock. Typical examples include voyage optimisation, route planning, weather routing, fleet performance monitoring and operational improvements that help vessels use fuel more efficiently under real operating conditions.

How should vessel performance improvements be prioritised?

The best starting point depends on the vessel's current situation. Operational improvements are often evaluated first because they can be implemented quickly and may help identify larger opportunities. Maintenance windows can be used to recover lost performance, while dry docks create opportunities for structural and propulsion-related efficiency upgrades. Newbuild projects offer the greatest freedom to optimise efficiency from the outset.

What is the difference between operational optimisation and retrofit upgrades?

Operational optimisation focuses on improving how a vessel is operated, using measures such as voyage planning, weather routing and performance monitoring. Retrofit upgrades involve physical modifications to equipment or vessel systems, often during maintenance stops or dry-dock periods. Both approaches can improve energy efficiency, and many operators use operational insights to help prioritise future retrofit investments.

How can you reduce CO₂ emissions from ships?

Reducing fuel consumption is one of the most direct ways to reduce vessel CO₂ emissions. Ship operators often combine operational optimisation, maintenance-driven performance improvements, propulsion upgrades, energy-saving technologies and newbuild design decisions to improve efficiency and lower emissions. The most effective approach depends on the vessel's operating profile, condition and available implementation window.

Not sure what should come first?

Many vessel owners have multiple opportunities to improve efficiency, but limited time, budget and implementation windows. A discussion with an expert can help clarify which actions make sense today, which should be planned for maintenance or dry dock, and which belong in future vessel projects.

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