🔍 Key Concepts
• MARPOL Annex VI fuel sulfur limits and what they require when entering or leaving a SOx Emission Control Area (ECA)
• The difference between territorial sea (12 miles), Economic Exclusion Zone (200 miles), and ECA boundaries
• What it means, in practice, to "plan" a fuel changeover on a ship burning both residual and distillate fuels
💭 Think About
• Ask yourself: Which of the listed distances is actually used in regulations to define the boundary of the SOx ECA, as opposed to general political or economic zones?
• Think about when you must already be on compliant low‑sulfur fuel: is it only once you are fully outside an ECA, or must the changeover be completed before crossing a certain boundary?
• Consider what your logbook entry for fuel changeover would relate to: change relative to national limits, ECA limits, or international waters/EEZ?
✅ Before You Answer
• Check which of the distances (3, 12, ECA limit, 200 miles) is directly tied in MARPOL Annex VI to SOx emission control areas, not just to generic maritime zones.
• Verify that fuel changeover procedures and records are linked to entering/leaving an ECA, not to entering/leaving an EEZ or territorial sea per se.
• Confirm from current regulations that the requirement is about being on compliant fuel when inside an ECA, and therefore how that affects when you must start the changeover on departure.