Shore power and DC fast charging for electric boats: a practical guide

Charging is where electric-boat ownership meets infrastructure — and where the gap between what is technically possible and what is operationally practical is widest. This guide walks through the two charging modes you will use (AC shore power and DC fast charge), how to size on-board hardware for both, and a realistic view of what marina infrastructure exists in 2026.

→ The spec calculator sizes shore-power and DC fast-charge inlets based on your pack and use pattern →

The two modes, briefly

AC shore power uses the marina's standard pedestal — typically 16 A or 32 A single-phase in Europe, 30 A or 50 A on US 240 V split-phase, plus three-phase 16/32/63 A connections on larger commercial pedestals. The boat's on-board charger (OBC) converts AC to DC and feeds the pack. Power levels: roughly 2–22 kW depending on pedestal and OBC.

DC fast charge bypasses the OBC entirely. A high-power off-board charger feeds DC directly to the pack through a CCS-Marine inlet, with the boat's BMS managing current and voltage limits over CAN bus. Power levels: 50–350 kW per the IEC 63379-1 standard finalised in May 2026.

For coastal and harbour-hopping cruising, AC shore power is the day-to-day reality. For passage planning or commercial fleet operation, DC fast charge changes what is possible — but only at marinas that have it.

Sizing your on-board AC charger

The OBC is the bottleneck on AC charging. Get this right and you avoid two failure modes: chargers oversized for typical pedestals (wasted cost, wasted weight) and chargers undersized for overnight pack recovery (boat sits at the dock half-charged).

Rule of thumb

Target full pack recovery from 20% to 95% in 8–10 hours on the smallest pedestal you regularly use. This sets minimum OBC power:

OBC_min (kW) ≈ pack_kWh × 0.75 / 9

So a 30 kWh pack needs roughly a 2.5 kW minimum OBC for overnight recovery; a 60 kWh pack needs roughly 5 kW; a 100 kWh pack needs 8.3 kW.

What pedestals deliver in practice

Marina pedestals are routinely shared, regulated, or current-limited below their nameplate rating. Assume you will see roughly 80% of the rated current under sustained load — fewer surprises that way.

Single-phase or three-phase OBC?

For pack sizes above ~50 kWh, a three-phase OBC (typically 11 or 22 kW) is the practical choice in Europe. On a single-phase 32 A pedestal you draw a single-phase share; on a three-phase pedestal you get full power. Single-phase OBCs above ~7 kW exist but stress the pedestal's single phase and are often current-limited by the marina.

US-market boats almost universally specify split-phase OBCs (Victron MultiPlus-II 12000 240V or equivalent) that draw equally on both legs of a 50 A pedestal.

CCS-Marine DC fast charge — what changed in May 2026

The IEC published IEC 63379-1 on 13 May 2026, formally finalising the CCS-Marine DC fast-charge standard at power levels up to 350 kW. Three details that matter for spec-time decisions:

1. Inlet rating up to 350 kW. Most early infrastructure runs at 50–150 kW; the headroom is for future commercial use.
2. OCPP 2.0.1 billing handshake is mandatory. A CCS-Marine boat will roam between marina networks the same way an EV roams between road charging operators.
3. Single-fault galvanic isolation is mandatory. This drives some boat-side architecture choices — your pack BMS and the inlet must isolate as a unit, not separately.

For boats specified in 2025 or earlier to the draft standard, the published version is close enough that most hardware is compliant or trivially upgradable. For 2027+ new builds, specify IEC 63379-1 explicitly.

Sizing your DC fast-charge inlet

The inlet sets a hard ceiling on charge power, but the pack BMS sets a soft ceiling on the actual current accepted. For a 60 kWh LFP pack rated at 1C charge:

• Max accepted DC current: 60 kW (1C × 60 kWh)
• Time from 20% to 80%: ~36 minutes at 60 kW
• Time from 20% to 80%: ~36 minutes regardless of whether the inlet is rated 150 or 350 kW, because the pack limits

This is the key insight: oversizing the inlet does not buy you charging speed. Size the inlet to match the pack's accepted C-rate plus modest headroom for future pack upgrades.

OCPP and billing: what to expect

OCPP 2.0.1 is the same back-end protocol used by EV public charging networks. For boat operators this means:

• A single RFID card or phone app authenticates across multiple marina networks
• Roaming agreements between Aqua superPower, Power Dock, and Marina Power Solutions are negotiated network-to-network, not boat-to-marina
• Itemised billing with kWh, time-of-use, and any idle fees is delivered to the boat's owner the same way EV charging receipts work today

Practically, 2026 cruisers should expect coverage similar to public EV charging in 2018 — present but patchy, with the densest networks in Northern Europe (Netherlands, Denmark, Sweden, southern Norway) and the US East Coast. The IEC publication unblocks the next wave of build-out; expect meaningful coverage growth through 2027–2028.

A realistic charging architecture for 2026

For a 14 m cruiser with a 60 kWh pack used mostly in coastal cruising:

• Primary: 11 kW three-phase OBC, 32 A three-phase shore inlet. Overnight recovery from any reasonable marina pedestal.
• Secondary: 16 A single-phase fallback for older marinas. Slower (3.5 kW) but ubiquitous.
• Optional: CCS-Marine DC inlet rated 50–100 kW for opportunistic fast charging at participating marinas. Adds €4,000–8,000 to the build cost; pays for itself only if you sail routes with multiple equipped marinas.
• Always: 2–4 kWp solar to cover hotel load while sailing or at anchor.

For pure coastal day-sailing, the secondary alone is often enough. For active cruising in mainland Europe, the primary becomes the daily driver. The fast-charge inlet is genuinely useful only on routes where you already know participating marinas exist along the way — verify before specifying.

What not to do

Three patterns to avoid:

1. Oversizing the OBC to "future-proof". A 22 kW OBC costs roughly 2× a 7 kW unit, weighs more, and produces more heat. Unless your pack is >80 kWh or you genuinely use three-phase 32 A pedestals daily, 7 kW single-phase or 11 kW three-phase is right.
2. Treating CCS-Marine as a substitute for AC charging. Even where the infrastructure exists, DC fast charging is expensive per kWh and is hard on pack longevity at high SoC. Treat it as the freeway gas station, not the home garage.
3. Skipping the galvanic isolator. A galvanic isolator or isolation transformer on the shore-power AC inlet protects against stray-current corrosion on your underwater metal. This is not optional for a boat that spends time at the dock.