Westerly Oceanlord 41 electric repower: motor, battery and cable sizing
The Westerly Oceanlord 41 is a 12.3 m monohull with a 10.74 m waterline and 9,470 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 — Oceanlord 41 (Westerly), checked 23 October 2026
Motor power
10 kW
9.5 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
The boat
- Length
- 12.34 m
- Waterline length
- 10.74 m
- Beam
- 4.11 m
- Displacement
- 9,470 kg
- Hull
- Fin keel
- Designer
- Ed Dubois / Mike Parham
- Builder
- Westerly Yachts Ltd. (UK)
- Built
- 1990–
- Number built
- 100
- Original engine
- Volvo MD17D — 43 hp
Power needed by speed
| Speed | Shaft power |
|---|---|
| 3 kn | 1.8 kW |
| 4 kn | 3.3 kW |
| 5 kn | 5.8 kW |
| 6 kncruise target | 9.5 kW |
| 7 kn | 15.2 kW |
| 8 knhull speed | 23.9 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
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 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.
Westerly Oceanlord 41
Common questions
How many kW does a Westerly Oceanlord 41 need for electric propulsion?+
About 9.5 kW to hold 6 knots — 75% of its 8-knot hull speed — so the configurator suggests a 10 kW motor. Power rises steeply above that: about 23.9 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 Westerly Oceanlord 41 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 Westerly Oceanlord 41 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.
More on this size of boat
40-foot sailboat electric repower