50+ essential terms every ship operator, fleet manager, and bunker trader should know — from fuel specifications to regulatory compliance.
| Term | Definition |
|---|---|
| AER | Annual Efficiency Ratio — the methodology used to calculate CII. Formula: CO₂ emissions / (DWT × distance sailed). Measured in grams CO₂ per tonne-mile. |
| BDN | Bunker Delivery Note — the official document provided at every fuel delivery per MARPOL Annex VI. Records quantity, fuel type, density, viscosity, sulfur content, and supplier details. Must be retained onboard for 3 years. |
| Bunker Stem | A single fuel delivery to a vessel. "Stemming" refers to the process of arranging and receiving a bunker delivery. |
| Cat Fines | Catalytic fines — aluminium and silicon particles (Al+Si) from refinery FCC (Fluid Catalytic Cracking) process. ISO 8217 limit: 60 mg/kg as delivered, 15 mg/kg at engine inlet after onboard purification. The most damaging fuel contaminant. |
| CCAI | Calculated Carbon Aromaticity Index — indicates ignition quality of residual fuel oil. Calculated from density and viscosity. ISO 8217 limit: 870. Higher values indicate poor combustion characteristics. |
| CII | Carbon Intensity Indicator — IMO operational measure rating ships A (best) to E (worst) based on CO₂ emissions per transport work. Mandatory since January 2023 for ships ≥5,000 GT. |
| CP | Charter Party — the contract between a vessel owner and charterer. Contains terms for hire rate, bunker clause (who provides fuel), and operational responsibilities. |
| DSO | Days Sales Outstanding — average number of days a client takes to pay an invoice after it is issued. Key credit risk metric in bunker trading. |
| DWT | Deadweight Tonnage — the total weight a vessel can carry including cargo, fuel, water, crew, and provisions. Used in CII calculations as a proxy for vessel capacity. |
| ECA | Emission Control Area — designated sea areas with stricter emission limits. Sulfur limit 0.10% (vs 0.50% global). Current ECAs: Baltic, North Sea, North America, US Caribbean. |
| EEDI | Energy Efficiency Design Index — mandatory design efficiency standard for new-build ships. Measures grams CO₂ per tonne-mile by design, not operation. |
| EEXI | Energy Efficiency Existing Ship Index — one-time technical efficiency measure for existing ships, effective January 2023. Ships exceeding the limit must reduce engine power or install efficiency devices. |
| EU ETS | European Union Emissions Trading System — cap-and-trade carbon pricing. Ships must surrender EU Allowances (EUAs) for CO₂ emissions on voyages to/from/within EU ports. Phase-in: 40% (2024), 70% (2025), 100% (2026+). |
| EUA | EU Allowance — one EUA permits emission of 1 tonne CO₂. Current price: €65-85/tonne. Traded on exchanges like ICE and EEX. |
| FCC | Fluid Catalytic Cracking — refinery process that produces lighter fuels from heavy residuals. Source of catalytic fines (cat fines) in bunker fuel. |
| Flash Point | Minimum temperature at which fuel vapor ignites. SOLAS safety requirement: ≥60°C for all marine fuels. Below 60°C = fire/explosion risk, vessel can be detained. |
| FOBAS | Fuel Oil Bunker Analysis Service — Lloyd’s Register fuel testing laboratory. Provides independent analysis of bunker fuel samples. |
| FuelEU Maritime | EU regulation setting GHG intensity limits on energy used by ships in EU waters. Targets: -2% (2025), -6% (2030), -14.5% (2035), -31% (2040), -80% (2050) vs 2020 baseline. |
| GHG Intensity | Greenhouse gas emissions per unit of energy, measured in gCO₂eq/MJ. Used in FuelEU Maritime compliance. VLSFO baseline: ~91.2 gCO₂eq/MJ (well-to-wake). |
| HSFO | High Sulfur Fuel Oil — residual fuel with sulfur content >0.50%. Can only be used with approved exhaust gas cleaning system (scrubber). Typically 0-120/MT cheaper than VLSFO. |
| IG Club | International Group of P&I Clubs — 12 mutual insurance clubs providing marine liability cover for ~90% of world tonnage. Tier 1 P&I coverage is the gold standard. |
| IMO | International Maritime Organization — UN specialized agency responsible for shipping safety and environmental regulations. Sets MARPOL, CII, EEDI/EEXI rules. |
| IMO 2020 | Global sulfur cap regulation effective January 1, 2020. Maximum sulfur content 0.50% for all marine fuels worldwide (down from 3.50%). Also called the "sulfur cap." |
| ISO 8217 | International standard for marine fuel specifications. Defines quality requirements for residual fuels (RMA-RMK) and distillate fuels (DMX-DMB) including limits for density, viscosity, sulfur, cat fines, water, CCAI, and more. |
| KYC | Know Your Customer — document verification process for counterparty due diligence. In bunker trading: Certificate of Incorporation, financial statements, UBO declaration, bank references, trade references. |
| LSMGO | Low Sulfur Marine Gas Oil — distillate fuel with sulfur ≤0.10%. Used in ECAs, for port operations, and auxiliary engines. Higher quality and price than VLSFO. |
| MARPOL | International Convention for the Prevention of Pollution from Ships. Annex VI covers air pollution and sets sulfur limits, NOx limits, and energy efficiency requirements. |
| MGO | Marine Gas Oil — distillate marine fuel. Clean-burning, low viscosity. Used for auxiliary engines, port operations, and in ECAs. |
| MRV | Monitoring, Reporting, and Verification — EU regulation requiring ships to monitor and report CO₂ emissions for voyages to/from EU ports. Feeds into EU ETS obligations. |
| Noon Report | Daily operational report from the vessel at 12:00 local time. Contains position, speed, weather, fuel consumption, ROB levels, and engine parameters. Primary data source for performance analytics. |
| P&I Club | Protection and Indemnity Club — mutual insurance providing liability cover for shipowners including cargo damage, pollution, crew, and third-party claims. |
| PSC | Port State Control — inspection regime where port authorities verify foreign-flagged ships comply with international conventions. Can detain vessels for sulfur violations, safety deficiencies. |
| RFQ | Request for Quotation — formal inquiry sent to bunker suppliers requesting price quotes for a specific fuel grade, quantity, port, and delivery date. |
| ROB | Remaining on Board — fuel quantity remaining in vessel tanks. Tracked by fuel grade (VLSFO, LSMGO, HSFO). Critical for procurement planning and regulatory reporting. |
| SEEMP | Ship Energy Efficiency Management Plan — mandatory document for every ship describing measures to improve energy efficiency. Must include CII corrective action plan if rated D or E. |
| SFOC | Specific Fuel Oil Consumption — fuel consumed per unit of power output, measured in g/kWh. Typical 2-stroke marine diesel: 165-185 g/kWh. Lower is better. |
| Scrubber | Exhaust Gas Cleaning System (EGCS) — device that removes sulfur oxides from exhaust gas, allowing use of cheaper HSFO while meeting emission limits. Open-loop scrubbers discharge wash water to sea (banned in some ports). |
| TSP | Total Sediment Potential — measures the tendency of fuel to form sludge and sediment. ISO 8217 limit: 0.10%. High TSP indicates fuel instability and potential for filter blockages. |
| UBO | Ultimate Beneficial Owner — the natural person who ultimately owns or controls a company. Required disclosure for KYC/AML compliance in bunker trading. |
| VLSFO | Very Low Sulfur Fuel Oil — residual fuel with sulfur content ≤0.50%. The standard marine fuel since IMO 2020. Blended from various refinery streams, quality varies significantly between suppliers and ports. |
| VPS | Veritas Petroleum Services — independent fuel testing laboratory. Along with FOBAS, one of the two major providers of independent bunker fuel analysis worldwide. |
| Well-to-Wake | Full lifecycle emissions accounting from fuel production (well) through combustion onboard (wake). Used in FuelEU Maritime. Includes upstream emissions that tank-to-wake methods exclude. |
Understanding BDN parameters, ISO 8217 limits, and what happens when fuel is off-spec.
How CII is calculated, what D/E means, and strategies to improve your rating.
Scope, phase-in schedule, and worked examples of carbon tax liability.
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