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Use this as a research brief, not a final answer. The ranges, fees, and rules below reflect how marina shore power typically work across the U.S., but every marina sets its own policy. Verify the specifics in writing with the dockmaster before you put money down.
Shore power is the lifeline of dockside boating. Wrong amperage means hot water but no air conditioning, or a tripped breaker every afternoon. Understanding the pedestal in your slip is non-negotiable.
Three standards dominate: 30A 125V (single hot leg, common for boats under 35 ft), 50A 125/250V (two hot legs, standard for 35–60 ft cruisers and modern center consoles), and 100A 125/250V (large yachts, trawlers with big AC loads).
Marinas bill power in three models: included in slip fee (rare except short-term transient), flat monthly per outlet ($30–$120), or metered ($0.18–$0.45/kWh). Liveaboards in Florida and California regularly burn $150–$400/month in summer AC.
Bring adapters. A 50A boat at a 30A-only marina can usually run reduced loads (lights, fridge, charger) on a 30-to-50 adapter, but not AC. A 30A boat at a 50A pedestal needs the reverse adapter. Most marina ships' stores stock both.
Amperage matchups
- • 30A — under 35 ft, light loads
- • 50A — 35–60 ft, AC and water heater
- • 100A — yachts, multiple AC zones
- • Twin 50A — large motor yachts
Power problems
- • Reverse polarity (galvanic damage)
- • Voltage drop on long cords
- • Tripped breaker from AC inrush
- • Corroded plug ends