Maritime Academy
SECA — Sulphur and Fuel Changeover
Select the correct limit and complete the vessel-specific changeover before the boundary.
Assess general/SOx-ECA fuel limits, approved equivalents and local additional requirements separately.
Rules and bulletins may change. Before operation or voyage, verify the latest official source and ship-specific applicability. This page is not permission, certification or a real-time risk notice.
ECA / SECA / NECA — Geography and voyage file
ECA is the umbrella term. Assess SOx fuel/sulphur requirements separately from NOx Tier III ship/engine eligibility. Sources checked: 17 October 2026.
- Baltic Sea — Scope and official sources
- North Sea — Scope and official sources
- North American — Scope and official sources
- US Caribbean — Scope and official sources
- Mediterranean — Scope and official sources
- Canadian Arctic — Scope and official sources
- Norwegian Sea — Scope and official sources
- North-East Atlantic — Scope and official sources
For exact boundaries compare corrected ENC/ECDIS, MARPOL definitions and official coordinates. Do not assume a simple 200-mile ring around all North American coasts. SOx/NOx dates are separated in the tables below.
IMO — Current resolutions and boundary instruments ↗Before entry → within the area → on exit
- Establish route and date: record official coordinates, ETA, SOx application date and NOx eligibility for each crossing.
- Verify BDN, samples, tank contents and remaining high-sulphur fuel. Assess mixing, temperature/viscosity and compatibility with the chief engineer.
- Complete fuel changeover before entry. Determine start using vessel procedures, service/circulation systems, consumption and maker constraints; no universal minutes/miles rule applies.
- Where required check certified SCR/EGR or other approved NOx mode, reagent, alarms and maker conditions. Low-sulphur fuel alone does not meet Tier III.
- Monitor fuel/NOx mode and failures within the area. Scrubber approval is not permission for wash-water discharge at every port.
- Record exit, changeovers and deviations under applicable procedures. Follow company/flag/relevant authority reporting for non-compliance. A FONAR is not an automatic exemption.
Inspection-ready document file
- Corrected ENC/route, boundary coordinates and entry/exit plan.
- IAPP supplement; relevant engines’ EIAPP, NOx Technical File and certified operating instructions.
- BDN for at least 3 years; MARPOL delivered sample until fuel is substantially consumed and in any event at least 12 months. Check other sampling provisions separately.
- Fuel changeover procedure; required tank quantity, date, time and position records; applicable NOx mode on/off records.
- Where applicable: EGCS approval/monitoring records, local discharge restrictions, failure and reporting evidence.
ECA, ETS/FuelEU, MARPOL Annex I special areas and IBF areas have different scopes. None substitutes for the others’ boundaries or permissions.
FOUR-STAGE TOPIC OVERVIEW
Establish applicability, then verify the operation
Area/limit
Fuel/documents
Ship-specific changeover
Completion/records
1 · Verify limit and area
The general Annex VI fuel sulphur limit is 0.50% m/m; operational SOx-ECAs use 0.10% m/m. Approved equivalent methods require documentation and local checks. A BDN value is only one part of fuel-management compliance evidence.
Reference: IMO — Sulphur limits and ECA implementation ↗2 · Implementation timeline
Check Baltic, North Sea, North American, US Caribbean and Mediterranean 0.10% requirements as applicable current regimes. Mediterranean application began 1 May 2025. Canadian Arctic/Norwegian Sea SOx application starts 1 March 2027; North-East Atlantic starts 1 September 2028.
Reference: IMO — MEPC.407(84), North-East Atlantic ECA ↗3 · Plan for the actual vessel
Assess service tanks/line volume, consumption, mixing, temperature/viscosity and compatibility through ship/engine procedures. Do not use guessed start times or a universal number of minutes. Plan completion before entry and required time/position/quantity entries.
Reference: IMO — Sulphur limits and ECA implementation ↗4 · Check port requirements
At-berth sulphur rules can apply outside an ECA. The UK chapter links MCA guidance. Scrubber/equivalent approval does not itself authorise wash-water discharge or establish acceptance in every port.
Reference: UK MCA — MGN 400 amendment 1, fuel at berth ↗SOx implementation snapshot — 17 October 2026
| Area | SOx fuel limit | Application status |
|---|---|---|
| Baltic Sea | 0.10% m/m | In application. |
| North Sea | 0.10% m/m | In application. |
| North American | 0.10% m/m | Within designated ECA. |
| US Caribbean | 0.10% m/m | Within designated ECA. |
| Mediterranean | 0.10% m/m | Since 1 May 2025. |
| Canadian Arctic | 0.10% m/m — future application | SOx application 1 March 2027. |
| Norwegian Sea | 0.10% m/m — future application | SOx application 1 March 2027. |
| North-East Atlantic | 0.10% m/m — future application | SOx application 1 September 2028; entry 1 September 2027. |
SOx snapshot, not NOx eligibility or a navigation-boundary chart. Verify official coordinates, stricter local requirements and approved equivalents separately.
MASTER • RESPONSIBLE OFFICER • COMPANY
Six field checks
- Mark SOx boundaries and application dates.
- Verify BDN/samples, tanks and fuel grades.
- Prepare ship-specific changeover calculation and precautions.
- Start in time to complete before entry.
- Record completion time/position and required tank quantities.
- Verify port/equivalent-method restrictions separately.
Educational checklist. Completion is not operational/compliance approval; use the relevant vessel permits/forms separately.
Documents to have available
- IAPP and any equivalent-method approval
- Changeover procedure and calculation inputs
- BDN, samples and fuel analysis
- Changeover and bridge/engine records
Onboard scenarios
Tank fuel complies, but old fuel remains in the lines.
Tank values alone are insufficient; complete and record line changeover under vessel procedures.
At a UK port outside an ECA.
Verify at-berth requirements separately; outside-ECA status is not an exemption.
LEARNING CHECK
Think of your answer, then reveal the explanation
Does a new ECA announcement immediately activate 0.10%?
No; confirm the SOx implementation date.
Is scrubber approval local discharge permission?
No; equipment approval and local discharge restrictions are separate.
Self-assessment only; no exam result, personnel record or competence certificate is generated.
Open the official sources
IMO — Sulphur limits and ECA implementation
IMO regulatory explanation
Open source ↗WWWCDN.IMO.ORGIMO — MEPC.392(82), Canadian Arctic / Norwegian Sea
IMO adopted amendment / boundaries
Open source ↗WWWCDN.IMO.ORGIMO — MEPC.407(84), North-East Atlantic ECA
Adopted amendment / geographic coordinates / construction criteria
Open source ↗WWW.GOV.UKUK MCA — MGN 400 amendment 1, fuel at berth
UK MCA guidance
Open source ↗Legal instruments, explanatory guidance and operational bulletins have different roles. Check later amendments and consolidated texts where needed. Access and external documents remain under the publisher’s control.