Our marina (and most other marinas) are not wired with GFI (ground fault) protection circuits.  Especially in the marine environment, this could pose significant risk while using AC powered devices on the dock or on the boats.  A faulty connector or worn cord could result in electrical current flowing in the water or through the boat resulting in a shock hazard.  An excellent explanation of this is detailed in a West Marine article (the link is https://www.westmarine.com/WestAdvisor/ELCI%20-GFCI-Electrical-Shock-Protection). In order to obviate this hazard, we have installed a short extension cord with a built in GFI protector to the electrical box attached to the dock box containing the battery packs, bilge pump, and electrical supplies.  Any tools or extension cords used on the dock should be connected only via this protection device.  The cord and protector are stored inside the dock box and remain connected to the electrical circuit breaker box which is attached to the dock box (see photos below).