Although there are a few marinas that have strange shore power connectors that you need to buy or rent from them, most are fairly standard throughout the Mediterranean. These are 240V 16A 3 Pin connectors (see picture) that are available in just about any hardware store or chandler, in almost any port, for a few Euros.
We bought ours in a hardware store in Horta, Azores. We also bought 25 meters of 25mm2 (14 AWG) 3 conductor wire.
On the boat side, we connected a standard, European household type (2 pin + ground), 240V female socket which connected, in turn, to the 240V/120V step down transformer.
I don't like to leave shore power connected to the boat when I am not onboard, so we simply ran the cable down the companionway to the transformer which sat below the companionway steps. This way I am reminded when I leave and lock up the boat to disconnect the cord. A more professional approach would be to have a deck connector that is permanently wired to the transformer.
Some marinas have 32 Amp power outlets which look like overgrown versions of the 16 Amp connectors and only cost a little more. We made up a short adapter cable with a male 32 Amp plug and a female 16 Amp socket. It might be a good idea to split the 32 Amp plug into two 16 amp sockets.
Another adapter cable that we made up was a 16 Amp male to two 16 Amp females. This is useful, when you get to the dock and find all of the receptacles are occupied by other boats. You then simply unplug the neighbour (preferably after asking permission) and plug him and yourself into your double adapter cable to share the plug.
You may want to keep some extra 16 Amp plugs and sockets and wire onboard so that you can make up new adapters as the situation demands.
Shore power voltages vary considerably, depending on the quality of the marina wiring, the distance from the source and the number of boats drawing power on the same line. It is not uncommon to see voltages below 200 volts which can sometimes upset some equipment on board.Howard and Jayne [ Just Imagine ] 28-Jan-2008