Understanding marine fuel specs
Understanding marine fuel specifications: VLSFO, MGO and HSFO explained
Introduction
Marine fuels come in different grades, each with specific characteristics and applications. Choosing the right fuel depends on multiple factors, including vessel configuration, trading area, regulatory requirements and operational needs.
Understanding the differences between common marine fuels helps operators make informed decisions when planning bunker requirements.
VLSFO - The dominant fuel after IMO 2020
Very Low Sulphur Fuel Oil (VLSFO) became the most widely used marine fuel following the introduction of the IMO 2020 global sulphur cap.
With a maximum sulphur content of 0.50%, VLSFO enables vessels without exhaust gas cleaning systems to comply with international sulphur regulations.
However, VLSFO is not a single uniform product. Its characteristics can vary depending on the refinery and blending components used, making fuel specifications an important consideration.
MGO - Used where stricter limits apply
Marine Gas Oil (MGO) is a distillate fuel commonly used by vessels operating in areas with stricter emission requirements, such as Emission Control Areas (ECAs).
With a sulphur content of 0.10% or below, MGO is suitable for operations where compliance with lower sulphur limits is required.
Its characteristics differ from residual fuels, affecting storage, handling and onboard fuel management.
HSFO - Still relevant for scrubber-equipped vessels
High Sulphur Fuel Oil (HSFO) remains an option for vessels fitted with approved exhaust gas cleaning systems.
Although its use has declined since IMO 2020, scrubber-equipped vessels can continue using HSFO while meeting sulphur emission requirements.
Beyond sulphur: viscosity and density
Sulphur content is only one part of a marine fuel specification.
Viscosity affects how fuel is heated, transferred and injected into the engine. The correct viscosity range is important for efficient combustion and reliable engine operation.
Density influences fuel handling and purification processes onboard. Variations in density can affect separator performance and fuel management.
Other characteristics, defined under standards such as ISO 8217, also determine whether a fuel is suitable for a vessel’s specific requirements.
Why fuel choice depends on the vessel and route
The most suitable marine fuel depends on the operational profile of each vessel.
Factors influencing fuel selection include:
- Engine type and fuel system design
- Presence of scrubbers
- Trading routes and ECA requirements
- Local fuel availability
- Voyage duration and operational conditions
A vessel operating on international routes may have different fuel requirements from one operating mainly in regulated coastal areas.
Understanding the fuel behind the voyage
Selecting marine fuel is a balance between compliance, availability, technical requirements and operational efficiency.
A clear understanding of fuel specifications enables operators to better evaluate their bunker options and prepare for the requirements of different trading environments.
Selecting the right marine fuel starts with understanding the specifications. Contact us for support with your bunker requirements and fuel options.