Man inspecting a Wartsila engine

Want to cut costs and extend CII compliance? The top 4 ways good maintenance practices can help

Maintenance might seem like a ‘necessary evil’, a costly and time-consuming task that simply cannot be avoided. But when it’s well planned and performed it has a lot to bring to the table. Let’s look at how good maintenance practices can benefit your business.

With all the talk about decarbonisation, energy-saving technologies and future fuels it’s easy to forget that well-planned and executed maintenance alone can offer some big savings. When something works efficiently, say a team or a process, we say it’s running ‘like a well-oiled machine’. This captures the importance of good maintenance practices in a nutshell. Here are the top four benefits of good maintenance practices.

1 – You can avoid unpleasant, expensive surprises

Juha Kelkka, Director of the Transactional Sales Team at Wärtsilä highlights that taking good care of critical engine components helps you avoid knock-on problems further down the line, where the wear or failure of one component can lead to more extensive and expensive problems later.

The critical components to highlight are the:

  • cylinder heads, including the valves and valve seats
  • injection equipment such as the nozzle and plunger
  • anti-polishing ring and piston-related components
  • charge air system, including the cooler, turbocharger and air intake.
Critical components of vessel engine


If you look after these components at the very least, you’re on the right track to maintaining good engine reliability and efficiency. Unpleasant surprises caused by poor maintenance of these components can be time consuming and potentially very expensive to fix. What’s more, paying limited or no attention to them will compromise your fuel oil economy and negatively impact your OPEX and CII rating. 

Kelkka explains that there are some good housekeeping practices beyond regular component replacement that can help you to optimise engine performance. These include:

  • keeping your engine’s charge air cooler and turbocharger clean
  • monitoring the back pressure after the turbocharger, especially if you have exhaust gas after-treatment systems installed
  • keeping the air filters clean and engine room ventilation in good working order
  • regulating the charge air cooling capacity so it remains as close as possible to the dew point
  • controlling the fuel oil temperature, which affects the fuel’s viscosity; this is particularly important if you’ve changed to distillate fuel and have not adjusted the fuel oil cooling capacity.

2 – You can adjust your engine’s cooling capacity to match the fuel you’re using

Speaking about the fuel injection system, Kelkka highlights that a typical problem seen is with engines that were originally designed for one type of fuel but now run on another. You might have switched fuel, say from residual to distillate, but have you increased the auxiliary cooling capacity and equipment settings to match? If not, your fuel viscosity could be unnecessarily low, which can impact your engine’s reliability and efficiency. For example, it might lead to components wearing out more quickly, or increased fuel consumption due to delayed and prolonged injection timing.

3 – You can save fuel, and therefore money

You might be surprised to learn that each individual category of critical components listed above contributes quite a bit towards your engine’s overall fuel consumption. Kelkka breaks the numbers down in terms of the fuel consumption impact of each category:

  • Charge air system – up to 2%
  • Cylinder unit – up to 1%
  • Fuel injection system – up to 1.5%

These numbers might sound small, but when you’re burning thousands of tons of fuel a year, every single drop saved represents money in the bank and lower emissions. Keep these components well maintained and you’re saving your bottom line – and your CII rating.

4 – You can reduce emissions, potentially extending your CII compliance by years

The IMO’s CII regulations came into force in January 2023. As it stands, 45% of the merchant fleet risks non-compliance if no action is taken. Every drop of fuel saved can help to improve your vessel’s CII rating. This is why many operators are looking to energy saving technologies to help cut their fuel bills.

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To illustrate the impact of well-executed scheduled maintenance on your vessel’s CII rating, Kelkka presents a simplified example based on a simulation of a bulker vessel with a large bore 4-stroke main engine.

Scheduled maintenance can extend vessels CII compliance

The simulation demonstrates that, even though the CII regulations become stricter as time goes on, with proper maintenance it’s possible to keep your vessel compliant, with a C rating, for longer.

The example shows that:

  • without proper maintenance the example vessel could get exposed to corrective action plan by 2025
  • with proper maintenance the vessel remains compliant into 2026 and potentially even longer.  

Concluding, Kelkka summarises the influence that the choices you make regarding maintenance can have on your OPEX. Each case is unique, and the decisions you make in the short term can have significant long-term impacts – but essentially, put a little more effort in and you can get far bigger returns out: 

  • Well-executed maintenance not only avoids unpleasant surprises but could also cut your fuel bill by 50% of the amount invested in an overhaul.
  • If your engine is running on a different fuel to the one it was originally designed to use, you can optimise fuel consumption and reduce component wear by fine-tuning the cooling capacity and injection timing.
  • Ensuring a high-quality air supply – in terms of volume, temperature and cleanliness – to your engines along with charge air cooling helps you to optimise combustion and avoid excessive fuel consumption.
  • Planning what parts you need, when they are needed and when and where to perform maintenance significantly reduces both the cost of scheduled downtime and the risk of unscheduled downtime.
  • In terms of CII compliancy, a robust maintenance plan can help you keep your asset compliant for longer and therefore more attractive to potential charterers.
  • Finally, engine upgrades can be combined to maintenance to take full advantage of the scheduled downtime and to offset a share of maintenance cost with upgrades.  

Want to learn in more detail how good maintenance practices can save you money and support CII compliance? Watch the Planning maintenance in a changing environment webinar to find out.

We would be happy to discuss maintenance plans for your vessels. Please contact your Wärtsilä sales manager. 

Written by
Charlie Bass