40 ft catamaran
Repower sizing guide

40-foot catamaran electric propulsion

Twin saildrives, more space for batteries — but you size each side independently.

Start sizing this boatPre-filled with realistic defaults
Fits boats like
Lagoon 40Leopard 40Bali 4.0Fountaine Pajot Astrea 42Nautitech 40 OpenCatana 41Outremer 4X

Not an exact match? The wizard adjusts to your real numbers — these are reference hulls for the typical sizing.

2 × 10–15 kW
Continuous power
30–60 kWh total
Battery pack
150–220 A per hull @ 48 V
DC current
25–45 nm
Cruise range
What this replaces — vs a 50 hp diesel
At 50 h motored per season (typical cruiser). Slider on the full summary lets you adjust.
Diesel displaced
284 L
per season
CO₂ avoided
762 kg
per season
Quieter
−23 dB
52 vs 75 dB(A)

What this segment looks like

Why a 40 ft catamaran is a sensible repower target

A 40 ft cruising catamaran (Lagoon 40, Leopard 40, Bali 4.0) typically uses twin saildrives. Each hull needs its own 10–15 kW motor and battery — but shared bow/aft locker space gives you room for 40+ kWh per hull if range is the priority.

  • Size each hull as its own system — they share state of charge, not load.
  • Twin 10 kW saildrives match a typical 2× 30 hp diesel layout for handling and reserve.
  • Catamarans often have 800 W+ of solar — factor that into daily charge balance.
  • Hydro regen at 7+ kn while sailing can recover 200–500 W per hull on long passages.
Read next

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Solar charging for electric boats: sizing and integration guide

How to integrate solar panels with an electric boat propulsion system — panel sizing, MPPT controller selection, wiring, and realistic range contribution.

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Battery sizing for electric boat range: kWh, Ah, DoD, and reserve

How to size battery energy for cruising, daily sailing, or hybrid use—without getting surprised by reserve, DoD limits, and charge time.

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Frequently asked questions

40 ft catamaran — common questions

Quick answers to what most owners ask before starting a repower.

Should I size both hulls of a catamaran the same?+
Yes — each hull gets an identical motor, controller, and battery system. They share state of charge over a DC link in some installations, but treating each side as an independent system simplifies design and redundancy.
What motor power per hull on a 40 ft cat?+
10–15 kW per hull is typical — matches the 2× 30 hp diesel layout most production cats came with. Two motors give you handling and redundancy that a single bigger motor can't.
How much solar can a 40 ft catamaran fit?+
Production cats often have 800–1500 W of solar on the bimini and coachroof. Over a sunny day at anchor that's 4–8 kWh of free energy — meaningful against house loads and slow background charging of the propulsion bank.
Is hydro regen worth it on a catamaran?+
Cats sail fast under load and often hit 7–9 kn for hours, where hydro regen recovers 300–600 W per hull. Over an Atlantic passage that can offset a substantial fraction of fridge + autopilot consumption.
Can I use a single big battery shared between hulls?+
Possible but rare. The cabling between hulls becomes a weight and complexity penalty, and a shared bank loses the redundancy advantage of having two independent systems. Two banks is the dominant production layout.
Other segments

Different boat?

30 ft sailboat35 ft sailboat40 ft sailboatElectric launchTrawler yacht

Size your 40 ft catamaran now

Wizard pre-filled with realistic defaults for this segment. Free to run; PDF from €29.

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