Shore power — Alternative Maritime Power, onshore power supply, cold ironing, depending on who is writing the specification — lets a vessel shut down her auxiliary engines at berth and take her hotel and service load from the quay. The principle is simple. The conversion is a full electrical project touching the main switchboard, the protection philosophy and, usually, the vessel's class documentation.
Start with the load profile, not the connector
The first question is not which inlet to fit but how much power the vessel actually draws alongside, and how that varies — reefer load, cargo handling, HVAC in summer, tank heating in winter. A conversion sized to an average figure will trip on the peaks. We measure or reconstruct the real berth load profile before anything else, because it sizes the transformer, the cable and the breaker, and those three items dominate the cost.
The high-voltage side
Most commercial conversions land high voltage — typically 6.6 kV or 11 kV — and step it down on board. That means a shore connection switchboard, a transformer, and a connection point designed for the mechanical reality of a moving ship: tidal range, surge, and a cable that must be able to disconnect safely under load or in an emergency. The standard the surveyors will be reading is IEC/IEEE/ISO 80005-1 for high-voltage shore connection, with 80005-3 covering low-voltage arrangements for smaller vessels.
50 Hz, 60 Hz and the converter question
A large share of the world fleet runs at 60 Hz. A large share of European shore supply is 50 Hz. Where the vessel and her regular ports do not match, a frequency converter has to sit somewhere in the chain — on the quay if the port has installed one, on board if it has not. Converters are expensive, heavy and need cooling and space, so where that equipment lives is a commercial negotiation with the ports as much as an engineering choice. It is worth resolving early, because it changes the on-board scope completely.
Cable management is a berth decision, not a ship decision
Whether the cable is handled from the quay or from the ship depends on the berths the vessel actually calls at. Container terminals increasingly provide quay-side cable management; many other terminals do not, which pushes a reel, davit or crane onto the ship's deck along with the deck reinforcement and the space to put it. Reviewing the vessel's real trading pattern before specifying this is the difference between a system that gets used and one that stays disconnected because it is impractical alongside.
Protection, earthing and interlocks
The part that takes the longest to agree is rarely the hardware. Earthing arrangement, protection coordination between shore and ship, the interlocking that makes it impossible to parallel the shore supply with running generators outside a controlled synchronisation window, emergency disconnection, and the alarm and monitoring philosophy — all of it has to be documented and accepted, not just installed.
Class, flag and the approval path
A shore connection changes the vessel's electrical single line diagram, so it is a class-approved modification. Drawings go in ahead of the work, and the approval turnaround is a real item on the schedule rather than a formality. Where an owner is working to a regulatory deadline, this is the step that most often gets underestimated.
Fitting it into a drydock window
Much of the work — cable routing, foundations, transformer landing — 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.
None of this is exotic. It is ordinary marine electrical engineering done in the right order — and the order is what separates a conversion that is commissioned on time from one that is still waiting on a converter when the berth slot arrives.