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Marine Fuel Glossary
Marine fuel glossary
The bunkering and marine fuel terms used across our coverage, defined in plain language.
BDN
Bunker Delivery Note — the document recording the quantity and characteristics of fuel delivered to a vessel.
Bunkering
The supply of fuel to a ship, whether by barge, truck or pipeline at berth or at anchorage.
Cat fines
Catalyst fines, abrasive particles carried over from refining that can cause engine wear if not removed by purification.
Cutter stock
A lighter component blended into residual fuel to bring viscosity and other parameters within specification.
ECA
Emission Control Area — a designated sea area with stricter sulphur or nitrogen oxide limits.
HSFO
High sulphur fuel oil, typically around 3.5% sulphur, used mainly by scrubber-fitted vessels.
ISO 8217
The international standard defining marine fuel specifications and test parameters.
MGO
Marine gasoil — a distillate marine fuel used where residual grades are unsuitable or unavailable.
Off-spec
Fuel that fails to meet the agreed specification on one or more parameters.
Scrubber
An exhaust gas cleaning system that allows a vessel to burn higher sulphur fuel while meeting emission limits.
Stem
A confirmed bunker order: the quantity, grade, port and delivery window agreed with a supplier.
ULSFO
Ultra low sulphur fuel oil at 0.10% sulphur, used inside emission control areas.
VLSFO
Very low sulphur fuel oil capped at 0.50% sulphur, the standard marine fuel for non-scrubber vessels.
Viscosity
A fuel's resistance to flow, which determines heating and handling requirements on board.
For how fuel costs feed into voyage economics, see the freight rates guide, or follow our bunkers and marine fuel coverage.