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What’s New On The E-Outboard Market?

Several companies are at the forefront of electric boat propulsion, innovation, research, and technological development. At recent boat shows we examined many of the following:

Recent advancements in motor design and use of rare-earth materials in brushless permanent magnet motors with integral controllers have allowed dramatic reductions in overall size and weight of electric outboards. These newer electric motors incorporate very strong rare-earth magnets, alloys such as neodymium-boron-iron, along with other exotic mixes that significantly improve motor efficiency and power outputs. Similar technologies are being used in the latest generation of wind generators and are in everything from dishwashers to electric vehicles.

Outboards are developing not only in materials used, but also in design. Some electric outboards have a top-mounted electric drive motor, such as the Mercury Avator, along with Elco and Ray Electric Outboards; others such as Torqeedo Cruise have a submerged pod motor within a waterproof casing that reduces noise and enhances motor cooling.

A further development to increase efficiency over traditional hub drives is the rim motor drive, where the pipe/tunnel/cylinder is the fixed part of the electric motor, and the prop blades are attached to the rotor, the rotating part. These outboards are quiet and efficient due to water cooling and are less prone to fouling from weeds and debris. The Yamaha Harmo uses this technology, along with the Dutch company Rim Drive Technology that has a range of outboards available in North America.

The TEMO range from France, sold in the U.S., also shown at last year’s Annapolis Boat Show, offers the innovative TEMO 450 for tenders that weighs in at just 11 pounds and has a telescopic tube incorporating the battery and controls.

Mercury Marine offers its Avator range, starting with the 7.5e, which equates to a 3.5 hp gasoline motor. The quick-install battery modules are easy to handle and have a simple-to-read performance display. The company has innovated the electric drive motor using what it calls “transverse flux motor technology,” resulting in improved torque at lower speed and improved efficiency. It also allows for a smaller and more compact electric motor design, crucial on electric outboards. The Avator 20e and 35e models are larger outboard units that use modular nickel-manganese-cobalt (NMC) 48-volt batteries.

ePropulsion X40 in use on a blue pontoon boat.

ePropulsion X40, Photo: ePropulsion

White and gray Mercury e-outboard motor in use.

Mercury Avator 20e, Photo: Mercury 

Torqeedo, which was recently acquired by Yamaha, is an electric propulsion pioneer. Its extensive product range starts with 1- to 3-hp equivalent ultralight units designed for lightweight boats, fishing kayaks, and canoes. They weigh in at only 19 pounds. The new Travel series starts at 2.5 hp through 6 hp suiting tenders up to daysailers. The Cruise series ranges from 6 hp to 25 hp equivalents, while the Deep Blue systems are in-hull mounted systems for both power- and sailboats and run off 348-volt battery banks. These can be powered by third-party lithium-iron-phosphate (LiFePO4) batteries of proper voltage and battery management system (BMS) capacity.

ePropulsion has developed a range of recently launched units: the X20, X30, and X40, the latter having 40 kW of power (equivalent to around 54 hp) and operating on 96 volts using a LiFePO4 battery module. The manufacturer claims a remarkable powertrain efficiency of 88.2%, along with a 36% weight reduction with comparable gasoline-powered outboards. Other innovative features include integral electric steering, power trim and tilt, and control units that simplify installation and reduce the engine footprint. Prop design was also considered; the company says it has optimized hydrodynamic performance and reduced vibration.

Adult in a green wet suit carrying a battery and a Newport NT300 on a wooden dock.

Newport NT300, Photo: Newport

The smaller outboard models making up the Spirit and Navy Evo range go to 6 kW (8-hp equivalent). Given the popularity of electric tender and dinghy outboards, these are typified by the ePropulsion Spirit 1.0 Plus. These direct-drive units are rated at 3-hp equivalent and can push you along at 3 to 4 knots with a range of around 22 miles at half speed. The motor is like all units, a brushless type weighing 22 pounds for the short-shaft model, and a battery weight of 19 pounds. The integrated battery is a lithium-ion polymer type rated at 1276 Wh with a 3,000-cycle rating. Also useful is that it floats if accidently dropped over the side. A sensible option is an optional foldable solar panel input port. The standard charger unit recharge time is 8.5 hours, and the fast charger time is 3.5 hours. This can be powered by a third-party 48-volt external battery that meets the manufacturer’s specifications on voltage limits and continuous current. This unit has a five-year warranty and offers something extra for daysail applications, a hydrogeneration battery charging capability.

Elco is an industry veteran and has an extensive range that starts with the EP-5, 24-volt unit through to the EP-50 96-volt unit. Models incorporate water cooling for efficiency and protection against overheating.

Ray Electric motor in use.

Ray Electric, Photo: Ray Electric

Bearded adult male wearing a navy life jacket in a small white boat using a TEMO 450 electric motor.

TEMO 450, Photo: TEMO

Adult male and female on a white vessel in open waters on a sunny day.

Torqeedo Deep Blue installed on a Frauscher Alassio, Photo: Torqeedo

Ray Electric Outboards offers an extensive range starting with the System 300 10-hp equivalent running on 36 volts, the System 400 16-hp equivalent running on 48 volts, the System 600 20-hp equivalent running on 60 volts, and the System 700 22-hp equivalent running on 72 volts.

Minn Kota is synonymous with trolling motors, so it’s no surprise it has leveraged that knowledge base. Its E-Drive unit is a 2-hp equivalent to suit freshwater pontoon boats.

Newport offers its Next Generation NT-300 3-hp 36-volt unit with a derivative for kayaks.

About electric outboard ratings

The usual way to rate traditional gas-powered outboards is by horsepower. In the electrical world, power is rated in watts or kilowatts (kW), that is watts multiplied by 1,000. There’s a simple conversion where 1 hp equals 746 watts, so a 3-hp outboard has an equivalent rating of 2.24 kW.

To avoid confusion — and having to do math — many manufacturers are quoting outboard ratings using the term “hp-equivalent,” which helps. Like all electrical equipment and systems, what goes in experiences losses due to normal electrical resistance, heat, and mechanical losses. Electric outboard efficiencies can reach around 55% and more, much better than the typical maximum efficiency of around 25% in gas-powered units. However, to further complicate comparisons, the energy density of gasoline is very high compared to a battery, meaning there’s more energy stored in it than the energy that can be stored in a comparable-sized battery.

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Author

John Payne

Contributor, BoatUS Magazine

John C. Payne is a cruising sailor and professional marine electrical engineer and surveyor with a 28 year career in merchant shipping and the offshore oil industry. He is the author of The Marine Electrical and Electronics Bible, Motorboat Electrical and Electronics Manual and Understanding Boat Batteries all published by Sheridan House.