Nautitech 40 Open electric repower: motor, battery and cable sizing

The Nautitech 40 Open is a 12 m multihull with a 11.94 m waterline and 8,502 kg displacement. From those figures, the configurator's sizing model puts an electric conversion at 8 kW and 26 kWh on a 48 V system.

Boat data: sailboatdata.com — Nautitech 40 Open, checked 23 October 2026

Motor power

8 kW

7.4 kW needed at 6.5 kn

Battery pack

26 kWh

2 h at full rating, with reserve

DC design current

278 A @ 48 V

cabling burden: heavy

Range on that pack

13 nm

at 6.5 kn

Open the Nautitech 40 Open in the configurator Compare motors for 8 kW

The boat

Length: 11.98 m
Waterline length: 11.94 m
Beam: 6.91 m
Displacement: 8,502 kg
Hull: Catamaran
Designer: Marc Lombard
Builder: Nautitech (France)
Built: 2015–
Original engine: Twin diesels, 60 hp (the source doesn't say whether per engine or in total)

Power needed by speed

Speed	Shaft power
3 kn	1.1 kW
4 kn	2.1 kW
5 kn	3.6 kW
6 kn	5.9 kW
6.5 kncruise target	7.4 kW
7 kn	9.3 kW
8 kn	14.3 kW
8.4 knhull speed	16.9 kW

The configurator's power-per-tonne heuristic, not a tank test — real boats vary by about ±25% with hull form, fouling, sea state and propeller. Near hull speed the power climbs steeply.

48 V or 96 V

48 V systemconfigurator's choice

278 A

design DC current · cabling burden heavy · 120 mm² for a short run

96 V system

154 A

design DC current · cabling burden moderate · 50 mm² for a short run

Motor lines that cover 8 kW at 48 V

Oceanvolt

SD saildrives (SD6 – SD15)

Saildrive · 6–12 kW continuous · 48 V

Oceanvolt

AXC shaft drives (AXC12 – AXC36)

Shaft drive · 12–36 kW continuous · 48 V modules

Torqeedo

Cruise 12.0 FP (fixed pod)

Pod drive · 12 kW · 48 V

From our motor comparison, matched by power and system voltage only — check drive type and fit with the maker.

What these numbers assume

The published displacement. Your boat loaded for cruising is heavier — use your own figure in the configurator.
Cruise target of 6.5 kn, which is 75% of the 8.4 kn hull speed.
A shaft drive (assumed — the source doesn't say; a saildrive adds about 4%).
A pack sized for 2 hours at the motor's full rating, 15% reserve and 80% usable depth of discharge.

Nautitech 40 Open

Common questions

How many kW does a Nautitech 40 Open need for electric propulsion?+

About 7.4 kW to hold 6.5 knots — 75% of its 8.4-knot hull speed — so the configurator suggests a 8 kW motor. Power rises steeply above that: about 16.9 kW at hull speed. These are estimates from the boat's published waterline length and displacement; real boats vary by roughly ±25%.

What size battery does a Nautitech 40 Open need?+

The configurator sizes about 26 kWh of LiFePO4 for 2 hours at the motor's full 8 kW rating, with a 15% reserve and 80% usable depth of discharge — about 13 nautical miles at 6.5 knots. Cruising below full power stretches that.

Should a Nautitech 40 Open use 48 V or 96 V?+

At 8 kW the design DC current is about 278 A at 48 V (cabling burden: heavy) and about 154 A at 96 V (moderate). The configurator picks 48 V for this boat: it stays on 48 V unless the 48 V current reaches its "very heavy" level.