Deck Diaries 9: New Fuels Mean New Realities at Sea

When someone recently asked me which fuel I preferred for marine vessels, I paused longer than I expected. For most of my life at sea, fuel was a constant — cost-effective heavy fuel oil (HFO) first, later followed by low-sulphur fuel oil (LSFO), when the sulphur cap redefined bunkering routines worldwide. 
 

The factors we considered were price, availability, and timing. Today, the question comes with a longer list to choose from: liquefied natural gas (LNG), methanol, biofuels, or ammonia. Bunkering is now a strategic decision and not merely routine logistics. 
 

The transformation came with a series of developments in the industry, driven by the momentum of the IMO's greenhouse gas strategy. Ship operators need to follow a path towards net-zero emissions by mid-century, with more and more decarbonisation checkpoints along the way. 
 

What is surprising is how the change also affects daily life at sea. Switching to a new fuel type alters emissions, but it also reshapes a crew’s routines, training, and the maintenance tasks engineers handle. 

 

The Scale of the Shift: A Fleet in Transition

For years, decisions about fuel had been made far from the bridge. The numbers now tell a different story. As the IMO has set a course towards net-zero greenhouse gas emissions by or around 2050, the strong targets for 2030 and 2040 are already influencing fleets’ choices and investment timelines. 
 

The response from shipowners has been swift. Orders for alternative-fuel vessels — particularly LNG and methanol, with ammonia-ready designs emerging — have increased sharply in recent years. According to Lloyd’s Register's analysis of Clarkson’s data, in 2025, owners ordered 590 merchant and leisure vessels totalling 45.5 m gt, capable of operating on alternative fuels at delivery. The same study reveals that the total alternative fuel-capable orderbook now stands at 1,942 ships, with 1,259 set to use LNG, 385 to use methanol, 139 to use LPG, 53 vessels equipped to use hydrogen, 55 to use ethane, 45 to use ammonia, 22 to use biofuel, and 4 nuclear-capable. These numbers indicate that the industry is preparing for a long transition and is not relying on a single dominant solution. 
 

Ports are also moving. Key bunkering hubs have been expanding infrastructure to support LNG and methanol supply, with early investments and pilot projects appearing in Europe, Southeast Asia, and the Middle East. 
 

These trends, however, do not reflect a clean switch from one fuel to another. For the foreseeable future, fleets will operate with multiple fuel types simultaneously. The destination is clear for all, but the journey is complex, and the responsibility for navigating it will rest heavily with ship operators and owners. 

 

The Changes Felt Onboard 

Experience tells me that when fuels change, the impact is first felt in everyday routines. The differences become apparent early in how crews plan, operate, and maintain their ships. 
 

Fuel management becomes more complex
 

Voyage planning gains a new constraint
 

Training and safety culture expand
 

Maintenance and reliability systems 
 

 

The Hidden Complexity: Planning, Data, and Decision Pressure

What has changed over the years is the kind of approvals that have to be given from the captain’s desk. Earlier, our choices focused on safety, schedule and weather. They now carry additional aspects of fuel efficiency, emissions exposure and commercial impact. 

 

Speed adjustment and routine engine settings are two of the factors closely related to fuel choice. They change fuel consumption profiles and emissions metrics that regulators continuously track. 

 

Another dimension is added by route planning, which is not only about avoiding bad weather. It is related to fuel availability at the next bunkering point, how effectively the vessel operates en route, and the expectations tied to commercial schedules. 

 

The complexity of different forces has made high-frequency data more important for daily operations. Using real-time monitoring systems, crews can understand fuel consumption patterns in real time. They do not need to wait for noon reports. Emissions tracking also becomes a continuous activity. The bridge and the engine room do not work in isolation from the shore team, as decisions are continually shared, discussed, and supported by data streams flowing in both directions. 

 

To some captains, it may feel less like navigating a ship and more like choosing between trade-offs. The role of fuel remains the same in principle, but the factors to be evaluated for each decision are more intricate. 

 

Seamanship in a Multi-Fuel Future

The longer I watch this fuel transition unfold, the clearer it becomes that the story involves more than technology. It concerns people, habits and the way a mariner’s profession is evolving. New fuels bring novel systems — these systems change routines, demand skills relevant to their management and change the expectations of the crews who operate them. 

 

In the coming years, vessel owners and operators will need to keep their ways of working flexible and future-ready. Standard operating procedures will change, training will teach new techniques, and the toolkit of any new seafarer will be very different from the one most of us started with. Blending engineering awareness, data interpretation and risk management into everyday work, seamanship is stretching beyond traditional boundaries. 

 

Now that we have already sailed through the transition from HFO to LSFO, the wider decarbonisation journey simply asks us to adapt once again.

 

There is more complexity ahead, but the maritime industry has always been shaped by change — from steam to diesel to digital navigation. Each shift has asked more of the people at sea, and each time they have adapted. The latest fuel transition is simply the next chapter, and if history is any guide, it will be met with the same resilience and professionalism that have always propelled ships forward.