Plug the cord into your boat's inlet first, then into the dock pedestal, with both breakers off until it's fully locked in — and match the cord's amperage (30A or 50A) to your boat's inlet, never just the marina's outlet. MAURIPRO stocks the Marinco cordsets, inlets, and adapters to do this right. Get the sequence or the sizing wrong and you risk arcing, a tripped pedestal breaker, or a melted plug.
This guide is for the mid-size cruiser owner (~30-45 ft) who ties up at a new marina or boatyard and needs to get shore power connected safely — whether that's a first-time install of a boat-side inlet or just sizing the right cord and adapter for tonight's slip.
Shore power cords, inlets & adapters at a glance
| What you need | MAURIPRO SKU | Rating | Typical use |
|---|---|---|---|
| 30A shore power cordset | Marinco CS30-50 EEL (50 ft) | 30A / 125V | Most cruisers up to ~35-40 ft |
| 50A shore power cordset | Marinco CS504-50 EEL (50 ft) | 50A / 125/250V | Larger boats, A/C + multiple systems |
| Boat-side inlet, 50A | Marinco 6373EL-B Stainless Inlet | 50A / 125/250V | Flush-mount deck or hull inlet |
| 30A receptacle | Marinco 305CRR Receptacle | 30A / 125V | Boat-side or pedestal wiring |
| 30A-to-50A pigtail adapter | Marinco P503-30 EEL Pigtail | 30A-125V to 50A-125V | 30A boat plugging into a 50A pedestal |
| Two 30A-to-one 30A "Y" adapter | Marinco Y30-2-30 EEL | 2x30A-125V | Splitting a single pedestal circuit |
Shop all shore power cords, inlets & adapters →
What is shore power on a boat?
Shore power is AC electricity supplied from a dockside pedestal into your boat's onboard electrical panel through a dedicated marine cordset, so you can run air conditioning, battery chargers, outlets, and other AC loads without running your generator. Most North American marinas offer 30A/125V or 50A/125V-250V (split-phase) service; larger yachts may need 100A. The cord connects a female shore power inlet mounted on your boat to a male plug on the dock pedestal — never the reverse, since the boat-side connector must always be the one that's dead until it's fully seated.
How do you connect shore power to your boat?
Connect in this order, every time: 1) turn off the dockside pedestal breaker and your boat's main AC breaker; 2) plug the cord's female end into your boat's inlet and twist to lock; 3) plug the male end into the pedestal receptacle and twist to lock; 4) turn the pedestal breaker on, then your boat's main breaker on. To disconnect, reverse the sequence — boat breaker off, pedestal breaker off, unplug from the pedestal, then unplug from the boat. Never pull the plug live; the momentary arc at the pins is what pits contacts and eventually causes a connector to run hot.
How do you size a shore power cord — 30A or 50A?
Size the cord to your boat's inlet rating, not the other way around. A 30A/125V cordset delivers up to 3,600 watts and comfortably covers lighting, battery chargers, fans, and small appliances on cruisers up to roughly 35-40 ft. A 50A/125V-250V cordset delivers up to 12,000 watts across two hot legs, which is what larger boats need to run air conditioning, multiple chargers, and a galley's worth of appliances at once.
How do you install a shore power inlet on a boat?
A boat-side inlet mounts through a cored or solid section of hull or coaming, wired directly to the boat's main AC panel by a qualified marine electrician — this is not a DIY wiring job on a boat with a metal hull, bonding system, or galvanic isolator to consider. The inlet itself, like the Marinco 6373EL-B above, is a flush-mount stainless housing with a spring-loaded weatherproof cap; sizing follows the same rule as the cord — a 30A boat gets a 30A inlet, a 50A boat gets a 50A inlet, and mixing ratings defeats the point of matching cord to inlet. Budget for a backing plate and marine-grade sealant at the mounting flange; a leaking inlet is a direct path for water into a live AC connection.
Do you need an adapter for a different amperage or marina?
Yes, and this is the most common real-world shore power problem: your boat is wired for 30A but the marina only has 50A pedestals, or vice versa. A pigtail adapter like the Marinco P503-30 steps a 30A boat plug up to a 50A pedestal receptacle (or the P30-503 does the reverse), without changing the actual current your boat draws — the adapter doesn't give you more power, it just lets the connectors mate. A "Y" adapter like the Marinco Y30-2-30 lets you combine two 30A pedestal circuits into a single 30A boat inlet where a marina doesn't offer 50A service at all. Keep one 30-to-50 and one Y-adapter aboard if you cruise between marinas with mixed dock power.
Which shore power setup should I choose?
If your boat's main AC panel and inlet are already rated 30A, stay with a 30A cordset sized to your longest realistic dock distance (25 ft or 50 ft), and carry a 30-to-50 pigtail for marinas without 30A pedestals. If you're re-wiring or specifying a new inlet on a boat over 40 ft, or you're adding air conditioning, go 50A/125-250V from the start — retrofitting an inlet later costs far more than sizing it correctly once. On dual-cord boats needing more than 30A but not a full 50A circuit, a Y-adapter combining two 30A pedestal feeds is the lower-cost path.
Expert notes
From our electrical bench: the failure we see most isn't the cord, it's the connector pins — green corrosion or a discolored plug face means it's time to replace the whole cordset, not just clean it and hope. We also recommend a dielectric grease made for marine electrical connectors on the pins each season; it displaces moisture and measurably cuts pitting on boats that live on shore power full-time.
Common mistakes
- Plugging in live. Connecting or disconnecting with either breaker on causes an arc across the pins every time — the single biggest driver of connector wear and eventual overheating.
- Undersizing the cord for the run. A cord that's too short gets pulled taut across a finger pier and strained at the connector; always leave slack for tide and surge.
- Mixing amperage without an adapter. Forcing a 30A plug into a 50A receptacle (or the reverse) with a non-marine adapter, rather than a purpose-built pigtail, is a common source of loose, overheating connections.
- Ignoring ground-fault compliance. Under NEC 555.36 (effective January 1, 2026), marinas are required to ensure a connected vessel doesn't trip the dock's ground-fault protection — a well-maintained cord, inlet, and onboard wiring materially reduce the odds of nuisance trips or being denied a slip.
Frequently asked questions
What is shore power on a boat?
Shore power is AC electricity from a dockside pedestal, delivered to your boat's onboard panel through a locking marine cordset, so you can run AC loads without the generator. It's rated 30A/125V or 50A/125-250V at most marinas.
How do you connect shore power to a boat?
Turn off both the pedestal and boat breakers, plug the cord into the boat's inlet first and lock it, then plug into the pedestal and lock it, then turn the breakers back on — pedestal first, boat second.
What size shore power cord do I need?
Match the cord to your boat's inlet rating: 30A/125V for most cruisers up to roughly 35-40 ft, and 50A/125-250V for larger boats or boats running air conditioning and multiple high-draw systems.
Can I plug a 30A boat into a 50A shore power pedestal?
Yes, with a purpose-built 30A-to-50A pigtail adapter such as the Marinco P503-30 — the adapter only lets the connectors mate; it does not increase the current your boat's 30A system can safely draw.
How do I install a shore power inlet on my boat?
Mount a flush inlet rated to match your boat's cord and panel through a solid or backed section of hull or coaming, wired to the main AC panel by a qualified marine electrician, with marine sealant at the mounting flange.
Why does my shore power keep tripping the dock breaker?
Worn connectors, moisture at the inlet, or onboard wiring leakage can all trip a pedestal's ground-fault protection. Inspect the cord and inlet for corrosion first; under NEC 555.36 marinas are increasingly testing for this before granting shore power access.