Electric marine motors
Frequently Asked Questions
Electric power is used by a whole host of boats and vessels – from small tenders up to passenger ferries.
Different types of motor suits different boats. ePropulsion has electric solutions from portable outboard motors, long range and more powerful outboards able to power boats up to 5 tonnes, and inboard POD drive electric motors for day sailers up to 50’ ocean going cruising boats.
Yes they are. There is often confusion between electric power measured in kWh (kilo watt) and traditional engines measured in HP (horse power). Due to the immediate torque produced by electric motors from 0 rpm and upwards, the kWh as a measure does not really compare with the HP measure used for internal combustion engines. The kWh is a measure of input power, and HP is a measure of output power. Compared to an electric engine with a direct drive, the action of engine (gearings, propeller shaft etc) considerably erodes the power efficiency of oil based fuel and the actual power output at the propellor. For example, 15kW electric power provides the same torque as a 40hp Yanmar diesel engine. For the time being, this is how the market is comparing it, and how the ePropulsion engines broadly equate:
|ePropulsion motors:||Similar to:|
|Spirit 1.0 Plus outboard 1kWh motor||3.5 hp outboard motor|
|POD Drive or Navy 3.0 Evo 3kWh motor||6 hp motor|
|POD Drive or Navy 6.0 Evo 6kWh||9.9 hp motor or outboard|
Increased power for inboard propulsion can be achieve by fitting twin POD drives.
The distance you can go is determined by the size of and number of batteries you have.
Your speed affects your motoring range. Lower speeds use less energy and motoring permanently at full throttle will use most power.
Your range is also influenced by sea state, currents and windage, as with all boating under power, plus your ability to regenerate battery charge whilst underway.
For cruising sailboats your engine is an auxiliary source power, for either when there is no wind, the wind is from the wrong angle or for the start and end of a voyage – leaving your berth or anchorage.
24’ sailboat – set up with 3kWh motor + 9kWh battery (1 x E Series 175)
5 knots = 30 miles, 6 hours
7 knots = 21 miles, 3 hours
30’ sailboat – set up with 6kWh motor + 18kWh battery (2 x E Series 175)
5 knots = 50 miles, 10 hours
7 knots = 21 miles, 3 hours
The ePropulsion motors can be used with up to 16 x 9kWh batteries with give 144 hours of motoring at full power, on the most popular model the Spirit 1.0 Plus outboard motor.
If you are not sure which motor will best suit your vessel, please complete our Motor Consultation Form with details about your boat, and we will get back to you.
Batteries can be recharged at any level of charge without any damaging effects happening to the cells.
All batteries option can be charged with solar or hybrid generated power whilst they are simultaneously in use and discharging power.
Batteries are available with a range of charging options, including 240V chargers that plug into mains power, either at home or on a marina berth standard power supply.
Batteries can also be recharged by:
- solar power supply – such as a fixed or portable solar panel
- other onboard power sources – such as a generator powered by wind, diesel, petrol or hydrogen
- using the hydro-regeneration capability on sailing boats, where at over 4 knots of boat speed the propeller automatically recharges the batteries
Rather like filling your engine with fuel, or recharging your car, it’s about planning ahead for the voyage you are undertaking. It’s un-seamanlike to set off with insufficient fuel or water on board for any voyage and this is no different for electric power.
Just the same as you might call into a port or marina for fuel, water and provisions, you’ll call in for recharging.
Set up for your planned voyages by having:
- Sufficient batteries on board for the trip you have in mind – eg a cross channel under motor
- Combine battery power with regeneration options on board – such as hydro generation whilst sailing, solar or wind power supplies
- Hybrid sources – such as a generator (diesel or hydrogen) or portable brief case sized generator for a specific trip, on board as a back-up power supply
All ePropulsion LiFePO4 batteries boast a remarkably long lifespan with at least 3000 charge cycles, translating to a potential 20-30 years before reaching their end of life.
When that time comes, they are fully recyclable. These batteries can be either repurposed for another role or reconditioned for continued use. Unlike oil and its by-products like sulphur, once the materials in a LiFePO4 battery are used, they can be recycled and utilized again and again.
While no mining process can be deemed entirely environmentally friendly, whether it's for resources like tin, copper, coal, or oil, it's essential to understand the broader context. Humans have been engaged in mining and drilling activities for thousands of years, particularly in the recent past for oil, which has been extensively used for powering vehicles, producing plastics, and generating various non-recyclable by-products in the developed world.
The oil industry, in particular, has witnessed several significant environmental catastrophes due to mishaps at drilling sites or transportation errors, causing extensive harm to oceans and ecosystems.
In contrast, there have been no recorded incidents where lithium mining or its transportation led to the contamination of the world's oceans.
Installing an electric motor reduces running costs and maintenance, especially when using renewable recharging supplies, such as solar or hydro generation. In addition to be being kinder to the environment, and not requiring fuel, oil, new parts or servicing, it will release considerable space on board which can be used for other purposes. See our comparison chart:
|Example boat type:||New Diesel engine||ePropulsion POD Drive|
|21’ sailing boat||Yanmar 1 Saildrive £5799||POD Drive 3.0 Evo + 1 x E80 battery & controls
Same with E175 battery £6450
|Rapier 550 Catamaran
|2 x Yanmar saildrive
£20,156 – motors only
|2 x POD 6.0 Evo – 36kWh (4 x E175 battery) and controls|
|Additional extras||Coolant systems
Generator (portable or fixed)
|Fuel costs||Marine diesel £1.04 / litre||0.15p / kW|
|Maintenance||Annual servicing and repairs||None|
|Spare parts||Per service / repair||None – unless needed due to accidental damage|
|Outboard motors:||Mercury 4 stroke||ePropulsion Spirit 1.0 Plus|
|Additional extras||Petrol – each trip|
|Optional: Solar charger £90|
|Fuel costs (@ Cowes Harbour)||Petrol £1.54 / litre||0.15p / kWh
|Maintenance||Annual service ~ £200|
Repairs – as required
|Winterising||Annually ~ £125||None|
|Spare parts||Per service / repair||None|