A modern container ship does not switch off when she ties up. Her reefer boxes, cargo cranes, pumps, lighting and accommodation keep drawing power, and traditionally that power comes from diesel auxiliary engines running the whole time she is alongside — often a full day per call, metres from an urban waterfront. Alternative Maritime Power, or shore power, replaces that with a clean connection to the quay. Before we walk through the OOCL Montreal project, it is worth being precise about what the work involves, because owners routinely underestimate it.
Container ships are the first vessels the regulations reach. Under the European Union's FuelEU Maritime regulation, from 1 January 2030 containerships and passenger ships at berth in the EU's TEN-T core ports must draw their electrical demand from onshore power supply, and the Alternative Fuels Infrastructure Regulation obliges those ports to provide it. China already enforces shore-power connection at many of its berths. For a boxship trading to Europe or the Far East, a compliant shore connection is moving from optional to expected.
What is Alternative Maritime Power (AMP)?
Alternative Maritime Power (AMP) is a shore-to-ship electrical connection that lets a vessel shut down her auxiliary engines at berth and take her entire hotel and service load from the quay. The same thing is called shore power, onshore power supply (OPS) or cold ironing depending on the region and the specification. It is defined internationally by the IEC/IEEE/ISO 80005 standard family — 80005-1 for high-voltage connections and 80005-3 for low-voltage.
The principle is simple; the conversion is not. A shore connection changes the vessel's electrical single-line diagram, so it is a class-approved modification that touches the main switchboard, the protection philosophy and the ship's certification. On a container ship it also has to carry an unusually demanding load.
Why a container ship is the hard case
The berth load on most ship types is fairly steady. On a container ship it is dominated by refrigerated containers, and it is anything but steady: each reefer plug draws on the order of several kilowatts up to about 15 kW, the number plugged changes call by call, and demand climbs with ambient temperature. A large boxship can need several megawatts alongside at the peak. Size the connection to an average figure and it trips exactly when the ship is full and hot — the worst moment to lose power. The first job on any container conversion is to measure or reconstruct the real berth load profile, because that number sizes the transformer, the cable and the breaker, and those three items set the cost.
The high-voltage side
Most commercial container conversions land high voltage — typically 6.6 kV or 11 kV — and step it down on board. That calls for a shore-connection switchboard, a step-down transformer, and a connection point engineered for the mechanical reality of a working ship: tidal range, ranging on the lines, and a cable that must disconnect safely under load or in an emergency. The governing standard is IEC/IEEE/ISO 80005-1 for high-voltage shore connection, with IEC 62613 covering the plugs and couplers. Where the shore supply is 50 Hz and the ship's system is 60 Hz, a frequency converter is added — a real cost and lead-time item that has to be identified early.
Protection, interlocking and class approval
The part that takes longest to agree is rarely the hardware. It is the protection and control: the earthing arrangement, the coordination between shore and ship protection, and the interlocking that makes it impossible to parallel the shore supply with running generators outside a controlled synchronisation window. Add emergency disconnection and the alarm and monitoring philosophy, and all of it must be documented and accepted by class, not merely installed. Because the connection alters the single-line diagram, the drawings go in ahead of the work and the approval turnaround is a genuine line on the programme — the step most often underestimated against a regulatory deadline.
Why the yard sequence decides the schedule
Much of a shore-power retrofit — cable routing, foundations, landing the transformer — can be done with the vessel trading, if it is planned that way. What genuinely needs the dock is usually limited: hull penetrations, heavy lifts and the final tie-in to the main switchboard. Splitting the scope across a riding-crew period and a short dock window is normally cheaper than treating the whole conversion as dock work, but it only works if the long-lead items were ordered against the dock date rather than the survey date. Sequencing, not exotic engineering, is what separates a conversion commissioned on time from one still waiting on a converter when the berth slot arrives.
Case study: OOCL Montreal at Sefine Shipyard
OOCL Montreal is a 4,402 TEU fully cellular container ship owned by Orient Overseas Container Line (OOCL), IMO 9253739, roughly 294 metres long with a 32-metre beam and in service since 2003. She came into Sefine Shipyard in Türkiye for a combined yard period: standard docking and maintenance, propulsion-efficiency work — hub vortex absorber fins (HVAF) and a pre-swirl device — and the Alternative Maritime Power installation. Orion Marine delivered the AMP and marine-electrical scope inside that period.
As Sefine Shipyard put it, “As part of the OOCL MONTREAL project carried out at Sefine Shipyard - Türkiye, we have successfully completed the installation of the AMP (Alternative Maritime Power) system.” Working to the same dock schedule as the rest of the yard's package, we handled the shore-power electrical work so the vessel left commissioned and class-compliant rather than with an open item list — able to plug in and shut down her auxiliary engines wherever a quay offers the connection.
A vessel of this generation and size is a representative shore-power candidate: a mature Panamax-era boxship with a reefer-driven berth load, trading routes that increasingly touch shore-power-equipped ports, and a fixed dock window to work inside. The engineering was ordinary marine electrical work done in the right order — which, on a live yard period alongside HVAF and PSV installation, is exactly the discipline that matters.
What the project shows
For owners and operators facing the 2030 deadlines, OOCL Montreal is the point in practice: a container ship can be given a compliant, class-approved shore connection inside a normal docking, without treating the whole job as dock work, and without a schedule surprise — provided the load is measured properly, the standard is engineered to, and the long-lead items are ordered against the dock. That is the work we do, on our own account and alongside a yard's wider scope.
Frequently asked questions
- What is the difference between AMP, shore power, OPS and cold ironing?
- They are the same concept under different names. Alternative Maritime Power (AMP), shore power, onshore power supply (OPS) and cold ironing all describe supplying a berthed ship with electricity from the shore so she can shut down her auxiliary engines. The differences are regional terminology and the specification called up — high voltage under IEC/IEEE/ISO 80005-1, low voltage under 80005-3.
- Do container ships have to use shore power in the EU?
- Yes, on a defined timeline. Under the EU's FuelEU Maritime regulation, from 1 January 2030 containerships and passenger ships at berth in EU TEN-T core ports must draw their electrical demand from onshore power supply, subject to specific exceptions. The AFIR regulation separately requires those core ports to provide the shore-side connection by 2030.
- Can a shore power retrofit be done without drydocking the ship?
- Partly. Cable routing, foundations and transformer landing can often be completed with the vessel trading or during a riding-crew period. Hull penetrations, heavy lifts and the final tie-in to the main switchboard usually need the dock. Splitting the scope this way keeps the ship earning and shortens the dock window.
- How is a container ship's shore power capacity decided?
- By its real berth load, not a nameplate figure. Reefer boxes dominate and the load is peaky, so the connection must be sized to the measured peak — including a full reefer complement in high ambient temperatures — otherwise it trips under exactly the conditions it exists to cover. That peak sizes the transformer, cable and breaker.
- Which standard applies to a high-voltage shore connection?
- IEC/IEEE/ISO 80005-1 governs high-voltage shore connection (HVSC) systems, typically at 6.6 kV or 11 kV, with IEC 62613 covering the plugs and couplers. Low-voltage connections fall under 80005-3. A shore connection alters the vessel's single-line diagram, so it is also a class-approved modification.