How Is Shore Power Engineered for a Full-Service Marina?

Every shore power design begins with the marina's slip inventory. The vessel classes drive everything: small sailboats on 20 or 30 amps, powerboats on 50 amps, and large yachts needing 100 amps or more per slip — sometimes on multiple pedestals. I work with the marina operator to document current slips, planned upgrades, and the transient mix, because a marina that courts superyachts needs a fundamentally different electrical backbone than a sailing club. Voltage selection follows the loads: 120/240-volt single-phase for smaller slips, three-phase service where large vessels and shoreside facilities demand it. Getting the slip mix right at the start prevents the two classic failures: an undersized service that sags on busy weekends, or an overbuilt one that wastes capital.

The life-safety design around a marina dock is as important as the power delivery. All metallic components — docks, pedestals, ladders, cleats — get bonded into a continuous grounding system tied to the shore grounding electrode, so there is no potential difference between touchable metal and the water. Equipment ground-fault protection goes on every shore power circuit, tested and commissioned to trip at the designed leakage threshold. I also design for the reality that boats bring their own faults: shore power pedestals need protection that catches a leaking vessel's shore cord, and the marina's electrical maintenance program should include periodic testing of ground-fault devices and bonding continuity. Corrosion eats grounding connections, so the design calls out accessible, inspectable connection points.

A marina electrical system earns its keep during commissioning, not during design. I load-test the distribution at realistic demand, measure voltage at the farthest pedestal under peak simulated load, and verify every ground-fault device trips within its designed threshold. Bonding continuity gets tested across the dock structure, and insulation resistance testing catches damaged cables before the system goes live. The operations team walks the system with the as-built drawings so they know which breaker feeds which pedestal before a boater ever plugs in. Here is the checklist I hand marina operators. • Verify ground-fault protection trips correctly on every shore power circuit • Load-test distribution and measure voltage at the farthest pedestal under peak demand • Test bonding continuity across docks, ladders, and pedestal enclosures • Confirm pedestal metering reads accurately and integrates with marina billing • Walk operations staff through as-builts so every breaker is mapped to its slip