ElectricPropulsion.org
Electric boat repower calculator
40 ft catamaran
Repower sizing guide

40-foot catamaran electric propulsion

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

See the full spec for this boatOpens on the results — every value editable
Fits boats like
Lagoon 40Leopard 40Bali 4.0Fountaine Pajot Astrea 42Nautitech 40 OpenCatana 41

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

8 kW
Motor power
26 kWh
Battery pack
278 A @ 48 V
DC design current
12 nm (2 h at 6 kn)
Range on that pack

Calculated by the configurator for the example boat below, sizing the pack for 2 hours at the motor's full rating with reserve. Open it to change any input.

What this replaces — vs a 16 hp diesel
At 50 h motored per season (typical cruiser). Slider on the full summary lets you adjust.
Diesel displaced
91 L
per season
CO₂ avoided
244 kg
per season

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. The configurator sizes the boat as a whole: about 7 kW to hold 6 kn on a 9 t cat, so an 8 kW total — roughly 4 kW per hull with twin drives.

  • Size each hull as its own system — they share state of charge, not load.
  • The configurator gives the boat's total: about 8 kW and 26 kWh, so roughly 4 kW and 13 kWh per hull.
  • Large roof areas suit solar — enter your expected daily yield in the configurator's charging step.
  • Hydro regen can contribute on passages; get yield figures from the drive manufacturer.
Read next

Related sizing guides

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A practical comparison of saildrive and shaft-drive configurations for electric boat repowers — installation complexity, efficiency, maintenance, and which suits your hull.

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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

A worked 30-footer example of the battery sizing chain, showing why motoring speed moves pack size more than reserve or depth of discharge.

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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?+
The configurator estimates about 7 kW in total for a 9-tonne, 40 ft cat at 6 kn, which with twin drives is roughly 3.5 kW per hull. Going a size up per hull adds reserve, and two motors give handling and redundancy a single motor can't.
How much solar can a 40 ft catamaran fit?+
Catamarans have more flat bimini and coachroof area than a monohull of the same length, which makes them well suited to solar. Yield depends on panel area, latitude, and season — enter your expected daily kWh in the configurator's charging step to see how much of the pack it covers.
Is hydro regen worth it on a catamaran?+
Cats can hold good speeds under sail for long periods, which is when hydro regen produces. How much it recovers depends on the drive, propeller, and boat speed — get the yield curve from the drive manufacturer and enter it in the configurator's charging step.
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

Opens on the results for this segment — every value editable. Free to run; PDF from €29.

Open the configurator