Hylas 42 electric repower: motor, battery and cable sizing

The Hylas 42 is a 12.8 m monohull with a 10.21 m waterline and 7,983 kg displacement. From those figures, the configurator's sizing model puts an electric conversion at 10 kW and 32 kWh on a 48 V system.

Boat data: sailboatdata.com — Hylas 42, checked 23 October 2026

Motor power

10 kW

8.6 kW needed at 6 kn

Battery pack

32 kWh

2 h at full rating, with reserve

DC design current

347 A @ 48 V

cabling burden: heavy

Range on that pack

12 nm

at 6 kn

Open the Hylas 42 in the configurator Compare motors for 10 kW

The boat

Length: 12.83 m
Waterline length: 10.21 m
Beam: 3.96 m
Displacement: 7,983 kg
Hull: Fin keel, spade rudder
Designer: German Frers
Builder: Queen Long Marine (Taiwan)
Built: 1985–1990
Number built: 22
Original engine: Universal — 50 hp (model not listed)

Power needed by speed

Speed	Shaft power
3 kn	1.6 kW
4 kn	3 kW
5 kn	5.2 kW
6 kncruise target	8.6 kW
7 kn	13.9 kW
7.8 knhull speed	20.1 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

347 A

design DC current · cabling burden heavy · 150 mm² for a short run

96 V system

193 A

design DC current · cabling burden moderate · 70 mm² for a short run

Motor lines that cover 10 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 kn, which is 75% of the 7.8 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.

Hylas 42

Common questions

How many kW does a Hylas 42 need for electric propulsion?+

About 8.6 kW to hold 6 knots — 75% of its 7.8-knot hull speed — so the configurator suggests a 10 kW motor. Power rises steeply above that: about 20.1 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 Hylas 42 need?+

The configurator sizes about 32 kWh of LiFePO4 for 2 hours at the motor's full 10 kW rating, with a 15% reserve and 80% usable depth of discharge — about 12 nautical miles at 6 knots. Cruising below full power stretches that.

Should a Hylas 42 use 48 V or 96 V?+

At 10 kW the design DC current is about 347 A at 48 V (cabling burden: heavy) and about 193 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.