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Small and medium gas carrier

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Diverse operations require flexible systems to maximise efficiency

Small and medium gas carriers generally transport liquid natural gas (LNG) or liquid petroleum gas (LPG), or other chemical products in gaseous form. Some vessel designs may be tailored for bunkering or ship-to-ship operations. Vessels in this size class need to be adaptable for varying voyage distances, loading conditions, and sailing speeds as well as varying power requirements for cargo handling and port entry and exit operations. Vessel CAPEX and OPEX are crucial to secure profitable and competitive business.

Gas carriers sail under variable cargo loads and with varying operational profiles, meaning propulsive and electrical power requirements can vary greatly. As a result, owners must balance the need to minimise a vessel’s Energy Efficiency Design Index (EEDI) with the need to ensure that installed propulsive power is sufficient to cope with adverse weather conditions as required by the IMO’s MARPOL Convention.

Vessels carrying hazardous or pollutant goods are usually required to have backup steering and navigational systems in case of failure. Small and medium gas carriers also often sail in challenging waters such as channels or fjords, making a reliable propulsion system, effective steering capability and excellent manoeuvrability a must. They may also be sailing in environmentally sensitive areas with strict emission and underwater noise limits. In addition, port operations may take place close to urban areas where even stricter local environmental regulations apply.

Integrated solution for small and medium gas carriers

Hover or click on the symbols to reveal more information on the six parts of the integrated solution.

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    Small gas carrier DF-DE

    Wärtsilä dual fuel-diesel electric (DF-DE) propulsion system

    Emission reduction and operational flexibility are the main drivers behind the development of Wärtsilä propulsion systems for small and medium gas carriers. These highly adaptable, customised propulsion systems can be enhanced with a variety of advanced functionalities according to the intended operational profile of the vessel in question.

    A great option for this vessel type is a diesel-electric hybrid propulsion system that includes fuel-flexible medium-speed gensets, a switchboard and a propulsion motor connected to steerable aft thrusters, a forward tunnel thruster and a battery-based energy storage system (ESS). An integrated Energy Management System (EMS) ensures all the elements work seamlessly together, optimising energy flows to achieve the best performance in all operational modes.

    System operational modes for small gas carrier DF-DE

    Small gas carrier DF-DE

    Zero Emissions Mode
    Transit Mode
    Standby Mode
    Manoeuvring Mode
    Bunkering / STS Mode
    Hotel Mode
    Additional operating possibilities

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    Small gas carrier DF-DM

    Wärtsilä dual fuel-diesel mechanical (DF-DM) propulsion system

    Emission reduction and operational flexibility are the main drivers behind the development of Wärtsilä propulsion systems for small and medium gas carriers. These highly adaptable, customised propulsion systems can be enhanced with a variety of advanced functionalities according to the intended operational profile of the vessel in question.

    A great option for this vessel type is a hybrid propulsion system that includes a fuel-flexible medium-speed main engine, a geared propeller system, a shaft motor/generator (PTO/PTI) and a battery-based energy storage system (ESS) as well as an auxiliary genset. An integrated Energy Management System (EMS) ensures all the elements work seamlessly together, optimising energy flows to achieve the best performance in all operational modes.

    System operational modes for small gas carrier DF-DM

    Small gas carrier DF-DM

    Mechanical Mode
    Hybrid Mode
    Electric Mode
    Zero-Emission Mode
    Boost Mode
    Manoeuvring Mode
    Hotel Mode
    Main Engine Genset Mode

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    Medium gas carrier

    The Wärtsilä propulsion system for this vessel type has a main engine mechanically connected to a CPP through a one-step gearbox with PTO/PTI connection. This helps owners to balance the need to minimise a vessel’s Energy Efficiency Design Index (EEDI) and comply with the IMO’s MARPOL Convention while ensuring that installed propulsive power is sufficient to cope with adverse weather conditions. The Wärtsilä ProTouch Propulsion Control System offers a user-friendly interface and advanced features such as EcoControl. A GATE RUDDER™ can be added for superior efficiency and manoeuvrability and a bow thruster to further enhance manoeuvrability. 

    System operational modes for medium gas carrier

    Medium gas carrier

    Mechanical Mode
    Hybrid Mode
    PTH Mode
    Boost Mode
    Manoeuvring Mode
    Hotel Mode
    Main Engine Genset Mode

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    Hand-picked press releases

    Two Alpha Gas carriers to get enhanced operational support with Wärtsilä Lifecycle Agreement

    Jul 2, 2025, 11:00 by Wärtsilä Corporation

    Wärtsilä Corporation, Press Release, 2 July 2025 at 11AM EEST 

    Technology group Wärtsilä has signed a five-year Lifecycle Agreement with Greek, Athens-based LNG management company, Alpha Gas. The agreement covers two LNG carriers which each have four Wärtsilä 34DF engines and is aimed at giving Alpha Gas increased operational insight, availability, and better maintenance cost predictability. The order with Wärtsilä was booked in Q2 2025.  

    In today's legislative and economic environment, shipowners and operators are increasingly looking for support in maximising efficiency and use of their assets. For LNG carriers in particular, which have limited opportunities for unscheduled stops and downtime, they are specifically looking to safeguard the reliability of their vessels. 

    “Our emphasis is on enabling the highest level of efficiency and reliability throughout our fleet,” says Peter Lonski, Technical Director, Alpha Gas. “This agreement with Wärtsilä will help us achieve that goal, while at the same time allowing us to accurately predict our maintenance costs. We also expect to be able to extend the time between overhauls, thanks to the dynamic maintenance planning feature.” 

    The agreement with Wärtsilä will help Alpha Gas to optimise the operations and maintenance of these LNG carriers more effectively through 24/7 expert remote support and guidance for troubleshooting and maintenance using specialist diagnostic tools. It will allow Wärtsilä experts to directly monitor the vessels’ systems and employ advanced diagnostic tools to support the crew with troubleshooting activities and rapid fault resolution. The agreement will also help to minimise OPEX and lifecycle costs by enabling preventive interventions that can avoid the need for later expensive repairs and on-site visits. 

    “The maritime industry is complex with many moving parts; therefore, we take a consultative approach with our customers, working closely with them to tailor the agreement to their specific needs as a means to add value to their operations,” comments Henrik Wilhelms, Director, Agreement Sales, Wärtsilä Marine. “As every business model is unique, we are fully committed to ensuring our customers’ assets can deliver maximum value throughout their lifecycle. This is especially important in the context of the industry’s stringent environmental targets for net-zero by 2050.”  

    Wärtsilä signed a similar agreement with Alpha Gas in November 2024 covering two more LNG carriers. The four Alpha Gas sister vessels now covered by the Wärtsilä Lifecycle Agreement are the Energy Pacific, Energy Endeavour, Energy Integrity, and the Energy Intelligence.     

    Media contact for more information on this release:   

    Isabella Alder    
    Positioning and Strategic Communications Manager Wärtsilä Marine    
    Tel: +44 (0) 7792 681 757     
    marine.media@wartsila.com    

    Image caption: Wärtsilä has signed a five-year Lifecycle Agreement with Greek, Athens-based LNG management company Alpha Gas for two LNG carriers. The agreement is aimed at giving Alpha Gas increased operational insight, availability, and better cost predictability. © Alpha Gas  

    All Wärtsilä releases are available at www.wartsila.com/media/news-releases and at news.cision.com/wartsila-corporation where also the images can be downloaded.  

    Use of the image(s) is allowed only in connection with the contents of this press release. Wärtsilä images are available at www.wartsila.com/media/image-bank
      

    Wärtsilä Marine in brief     
    Wärtsilä Marine is a global pioneer in power, propulsion and lifecycle solutions for the marine market. We develop industry-leading technologies, advancing maritime's transition to new fuels. We support building an end-to-end digital ecosystem where all vessels and ports are connected. Ultimately, Wärtsilä Marine is driving the shipping industry forward on its journey towards a decarbonised and sustainable future through our broad portfolio of engines, propulsion systems, hybrid technology, exhaust treatment, shaft line solutions and digital technologies, as well as integrated powertrain systems. Our offering, which is underpinned by our performance-based agreements, upgrades, lifecycle solutions, decarbonisation services, as well as an unrivalled global network of maritime expertise, delivers the efficiency, reliability, safety, and environmental performance needed to support a safe and sustainable future for our customers, our communities and our planet.    
    www.wartsila.com/marine    

    Wärtsilä in brief 
    Wärtsilä is a global leader in innovative technologies and lifecycle solutions for the marine and energy markets. We emphasise innovation in sustainable technology and services to help our customers continuously improve their environmental and economic performance. Our dedicated and passionate team of 18,300 professionals in more than 230 locations in 77 countries is shaping the decarbonisation of our industries across the globe. In 2024, Wärtsilä’s net sales totalled EUR 6.4 billion. Wärtsilä is listed on Nasdaq Helsinki. 
    www.wartsila.com 

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