The MCA Approved Engine Course (AEC1 & AEC2) — the mandatory entry point for all professional engineers on small vessels and superyachts, and the foundation of the UK engineering career ladder.
The Approved Engine Course (AEC) is a UK Maritime and Coastguard Agency approved qualification created under STCW Convention Article IX and governed by MCA guidance including MSN 1859 and MIN 524. It is not itself an STCW certificate, so automatic international recognition cannot be assumed and should be verified with the relevant Port State Control. What it does do is act as the mandatory gateway: no qualifying sea service towards any MCA engineering officer Certificate of Competency is recognised unless the person already holds an AEC. There is no alternative entry route.
AEC Part 1 covers the fundamentals — compression and spark ignition engine principles, 2-stroke and 4-stroke cycles, fuel systems, cooling and lubrication, combustion air and turbocharging, electrical distribution and power transmission, hull fittings, and MARPOL pollution regulations. Roughly half the time is classroom theory; the other half is hands-on practical work in a dedicated workshop covering engine teardown, rebuild and fault-finding. AEC Part 2 builds on this foundation with more complex systems: refrigeration plants, hydraulic systems, lifting operations, potable water, sewage treatment, electrical distribution, maintenance scheduling, and legislation and management. Both parts run Monday to Friday across one week each, approximately 0900–1700, or back-to-back as a two-week combined package.
The Marine Engine Operator Licence (MEOL) is a separate MCA licence rather than a training course. It is obtained by passing an MCA oral examination after meeting qualifying service and certification requirements. It authorises service as marine engine operator on UK-registered vessels with propulsion power between 350 kW and 750 kW in non-STCW contexts. With the SV CoC structure now in place, it functions largely as a standalone qualification for smaller commercial vessels rather than a stepping stone to higher officer grades.
The full small vessel engineering ladder runs: AEC1 → AEC2 → (sea service + 2 weeks MCA-approved workshop skills training + MCA written exams + oral) → SV Second Engineer CoC (up to 9,000 kW, 3,000 GT) → 12 months as SV Second Engineer on vessels of at least 750 kW → SV Chief Engineer CoC (up to 3,000 kW, 500 GT, with progression to 9,000 kW, 3,000 GT). This covers the vast majority of the working superyacht world. The SV CoC structure replaces the old Y-ticket system entirely: Y4 maps to SV Second Engineer, and Y3/Y2/Y1 map to SV Chief Engineer grades.
For the very largest vessels — above approximately 3,000 GT or 9,000 kW, typically mega-yachts above 80–90 m — the full STCW EOOW and Chief Engineer Certificate of Competency on the large-ship route applies, which is a substantially more demanding separate pathway. For those operating non-STCW smaller commercial vessels, the route may run via the MEOL(SV) for vessels between 350–750 kW before escalating to the SV CoC structure as vessel size increases.
The AEC is also relevant to deck crew seeking a dual deck/engineer role — AEC1 at minimum is required for engineering sea service to count formally towards any MCA qualification. It applies equally to engineers on workboats, tugs, fishing vessels, research vessels, and patrol vessels under 3,000 GT and 9,000 kW, not only superyachts.
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