Fuel switching sounds simple: burn compliant fuel inside the zone, burn the cheaper fuel outside. In practice it is a timed engine-room operation with a legal deadline at the boundary, a set of log entries an inspector will check and, since 2025, three more areas to plan for. The Mediterranean Sea has been a sulphur Emission Control Area (ECA) since 1 May 2025. The Canadian Arctic and Norwegian Sea ECAs entered into force on 1 March 2026, with the sulphur limit applying from 1 March 2027. A North-East Atlantic ECA has been adopted but is not yet in force. "In force" and "enforceable for your ship" are not the same thing, and the dates in this guide separate them. For the technical superintendent this page covers the boundaries, the fuel changeover timing, the engine-side risks and the records that prove compliance. See how to plan ECA changeovers across your fleet in Marine Inspection, with checks, logs and corrective actions tracked per vessel.
ECA DEPARTURES BOARD
From "In Force" to "Enforceable": Which ECA Dates Bind Your Ship
Status as of October 2026. Check each date against your voyage plan before the next fixture.
Area
Key dates
Status
Mediterranean Sea
0.10% sulphur limit from 1 May 2025
LIVE
Canadian Arctic
In force 1 Mar 2026. Sulphur limit from 1 Mar 2027
LEAD-IN
Norwegian Sea
In force 1 Mar 2026. Sulphur limit from 1 Mar 2027
LEAD-IN
North-East Atlantic
Adopted. In force 1 Sep 2027. Sulphur limit from 1 Sep 2028
ADOPTED
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Boundaries: Where the 0.10% Limit Starts
Mediterranean Sea
Defined by coordinate points in the MARPOL Annex VI amendment. Plot the boundary on the passage plan chart.
Canadian Arctic
All Canadian Arctic waters. It extends the existing North American ECA.
Norwegian Sea
The Norwegian exclusive economic zone, including fjords and coastal waters, to the Russian border. It extends the North Sea ECA.
North-East Atlantic (adopted)
Exclusive economic zones and territorial seas of Portugal, Spain, France, Ireland, Iceland, the Faroe Islands, Greenland and mainland UK not already covered. Madeira, the Azores and the Canary Islands are excluded.
Once the North-East Atlantic ECA is in effect, it will link the Canadian Arctic, Norwegian Sea, North Sea and Mediterranean ECAs into one connected area. Always use the official coordinates and the latest chart updates for boundary decisions.
Limits are by mass. Inside an ECA the limit is five times tighter than the global cap, unless an approved equivalent such as an exhaust gas cleaning system is used.
The changeover is only half the job. The log entry is the proof. Log fuel changeovers free so every ECA entry and exit has a time, position and tank volume attached.
The Changeover Track: What Happens Before and After the Boundary
BEFORE
Start the flush early
Follow the written procedure and allow enough time for the fuel service system to be fully flushed.
ECA BOUNDARY
AT ENTRY
Be on compliant fuel
Log the volume of low sulphur fuel in each tank, and the date, time and position when changeover was completed.
INSIDE
Stay compliant
Keep bunker delivery notes and samples. Watch for pipe heating in cold waters.
EXIT
AFTER
Log the switch back
Record when the changeover out of the ECA started, with date, time and position.
Engine-Side Risks of Fuel Switching
2 C/min
Temperature change
Keep temperature change to about 2 degrees per minute at most to avoid thermal shock to fuel pumps and injectors.
130 vs 30 C
Viscosity control
Heavy fuel is injected at about 130 degrees C, while marine gas oil needs cooling to about 30 degrees C to reach the right viscosity.
BN
Cylinder oil
Lower sulphur means less acid. Too high a base number can cause liner wear, so review cylinder oil selection and feed rate.
Mix
Compatibility
Mixed fuels can cause filter clogging and starvation. Use onboard spot tests or laboratory compatibility tests.
Drill
Rehearse the switch
Crew should practise the procedure in safe water, not for the first time in a restricted channel.
Engine figures are best-practice guidance from a lubricant supplier, not regulatory limits. Always follow the engine maker's instructions for your plant.
Three Routes to Compliance
ROUTE A
Compliant fuel
Use fuel at or below 0.10% inside the ECA. Prove it with bunker delivery notes, samples and the changeover log.
ROUTE B
Exhaust gas cleaning
An approved exhaust gas cleaning system (scrubber) is an accepted equivalent. Check local washwater rules for the ports you call.
ROUTE C
Fuel unavailable
If compliant fuel could not be obtained, present evidence of attempts to buy it as planned. The ship need not deviate from its voyage to comply.
ECA Records an Inspector Will Ask For
| Record | What it must show | Superintendent check |
|---|---|---|
| Written changeover procedure | How changeover is done, with time to flush the system fully, in a language the crew understands | Procedure on board and known to the engine room team |
| Changeover log entries | Volume of low sulphur fuel per tank. Date, time and position at completion before entry, or at start after exit | Entries match the voyage and the boundary position |
| Bunker delivery notes and samples | Delivered and used fuel at or below 0.10% for ECA use | BDNs retained, samples sealed and labelled |
| Oil Record Book Part I | Bunkering entries consistent with the BDNs | No gaps between ORB and fuel records |
| IAPP Certificate and supplement | NOx Tier III details. For the Norwegian Sea, contract, keel-laying and delivery dates are tested | Supplement shows the dates needed for the areas the ship trades to |
| Fuel non-availability file | Voyage plan, supplier contacts and proof of attempts to buy compliant fuel | Prepared before it is needed |
Record requirements follow MARPOL Annex VI regulation 14.6 and Paris MoU guidance. Your flag may set the exact logbook format.
Prove Every ECA Entry and Exit
Keep changeover logs, bunker records and engine checks in one trail, so a boundary crossing is easy to show and easy to audit.
Free trial available. Or book a walkthrough built around your own fleet.
What Can Lead to Detention
!Fuel above the limit in use or carried for use, with no valid non-availability case
!Missing or invalid changeover records
!Fuel pipelines that cannot work in cold conditions
!Crew unfamiliar with the changeover procedure
!Voyage plan and fuel quantities that do not match
These points come from Paris MoU guidance on MARPOL Annex VI. Inspectors use judgement and act where there is an unreasonable threat of harm to the marine environment or the ship.
Which new ECAs are in force?
The Mediterranean Sea sulphur ECA has applied since 1 May 2025. The Canadian Arctic and Norwegian Sea ECAs entered into force on 1 March 2026, with the sulphur and particulate limit applying from 1 March 2027. The North-East Atlantic ECA is adopted and enters into force on 1 September 2027.
What is the sulphur limit in an ECA?
0.10% by mass in fuel oil, compared with 0.50% outside ECAs. An approved equivalent, such as an exhaust gas cleaning system, can be used instead.
When should the changeover be completed?
Before the ship enters the ECA. The ship needs a written procedure that allows enough time for the fuel system to be fully flushed, and the log must show when the changeover was completed and the position.
Do the new ECAs also cover NOx?
The Canadian Arctic and Norwegian Sea ECAs include nitrogen oxide limits, with Tier III applying to new ships under build-date tests. The Norwegian Sea uses contract, keel-laying and delivery dates. Check your IAPP supplement and class guidance. See how Marine Inspection tracks ECA records per vessel.
What if compliant fuel is not available?
The master should present evidence of attempts to purchase compliant fuel in line with the voyage plan. Port state guidance says the ship should not be required to deviate or delay unduly to comply, but the evidence must be ready.
Get Your ECA Records PSC-Ready
One system for changeover procedures, logs, bunker records and engine checks across every vessel in the fleet.
Free trial available. Or book a walkthrough built around your own fleet.
