Electric outboard motor: we test 12 options

An electric outboard motor is now a viable option for dinghy propulsion. Emrhys Barrell puts the latest outboards and trolling motors to the test

The electric outboard motor has been around for many years, but they have either been too low powered or their lead acid batteries have made them too heavy to lift in and out of a small tender, so petrol outboards have remained the engine of choice.

The development of lightweight lithium batteries has changed all this, making an electric outboard motor a practical alternative to petrol. With this in mind, we tested 12 models whose all-up weight, or the weight of their individual components, did not exceed the 14-17kg of a 2.5hp petrol outboard.

We took a selection of electric outboard motor units available on the market, and tested them in two situations, firstly on a Frib 275 folding RIB on the Lymington River to reproduce the situation of getting out to your boat in the tender. We then put them on a 4m skiff on the Thames, to see how they perform at higher speeds on a boat with a smoother underwater form and longer waterline on sheltered waters.

Speed: We measured speed using a handheld GPS, and electricity consumed using a clamp ammeter or the motor’s inbuilt power display. We converted these to the range you would achieve, either for a given power, or the full power of the motor’s battery.

Thrust: We measured static thrust using a spring balance. This is a somewhat crude test, as it measures the pulling power of a motor in a static boat, and therefore doesn’t allow the propeller pitch to work at its designed speed.

Function: We checked the stated weights of each of the motors and made a qualitative survey of their main features when used as a dinghy outboard.

We tested the trolling motors with a 60Ah lithium battery from Sterling Power, which cost £360, though you can use a heavier lead acid battery costing around £120 for a good quality AGM or gel. Don’t bother with leisure batteries, which will fail after 4 to 5 trips. You will need a good quality Lithium charger, which will add on £100 or more.

We haven’t included charging in this test, as this is dependent on the charger you are using, whether you are charging from 240V or 12V on board, and whether the power source is mains, a generator, alternator or solar. It’s worth noting that you will rarely be recharging from flat, and will rather be aiming to top up batteries after each use.

Trolling motor or electric outboard motor?

The options today are trolling motors with separate batteries – so called because they were mainly used as auxiliary slow-speed power for anglers, and integral-battery motors built for dinghy propulsion. These are the options a sailor will be looking at when thinking about changing to an electric outboard.

Trolling motors are still popular for low-speed applications, as they are simple and cheap, but they do need a separate 12V battery.

The integral battery motors are sophisticated units designed to give you more speed and greater range for a given power in a small boat, though for any 3-4m boat, the hull speed will limit how fast you can realistically go with any motor unless you start planing.

An electric outboard motor with an integral battery will often include displays showing speed, range at a given speed, and percentage of battery capacity remaining, but these features come with a higher price tag.

The trolling motors and integral battery models in our test were similar in weight and both come in at around the same total weight as a 2.5hp petrol engine.

Best electric outboard motor

Photo: Paul Wyeth

ePropolsion Spirit 1.0 EVO

Yachting Monthly’s best buy

The Chinese firm ePropulsion has been developing its electric outboard motor range and lithium batteries for some time. We tested the Spirit 1.0 Plus and Evo, both 1kW motors with integral batteries.

Clearly ePropulsion was influenced by Torqeedo, but there are some important differences. From the outset ePropulsion went for a direct drive motor, being quieter and avoiding gearbox problems.

The battery has a greater capacity than the original Torqeedo, and is still 30% higher than the latest version. It also floats – useful if you should drop it overboard.

Fitting the battery is a two-handed job, with the carrying handle being at the back, and latch lock at the front, which requires leaning over the transom to install it. You also cannot see the locating slots underneath, which isn’t quite so easy in a bobbing inflatable. The power cable socket is protected by a rubber cap.

You have a display, but it only shows power being consumed, voltage, and remaining runtime, which means it has larger figures, easier to read on a sunny day, but it lacks GPS speed or range.

It has the same trim settings as the Torqeedo, with a similar fiddly retaining split ring. It also has a magnetic kill cord. Three shaft lengths are available, catering for transom heights up to 61cm. The shaft is streamlined but rotates through 360º for maximum manoeuvrability and reverse.

ePropulsion Spirit 1.0 Plus specifications

Motor weight:  10.5kg
Battery weight: 9kg
Battery capacity: 1276Wh
Top speed RIB: 4.5mph
Top speed skiff: 6.0mph
Thrust: 68lbs
Price: (complete) £1,650

Website www.epropulsion.com

Photo: Paul Wyeth

ePropolsion Spirit 1.0 EVO

Yachting Monthly’s best in class

The 1.0 EVO has the same dimensions and performance as the Spirit, but it has the options of a removable tiller, plus remote controls and steering, but the real innovation is that it offers regenerative charging while you are sailing, putting 40W at 4 knots, and 300W at 10 knots back into the battery.

You can even have a wristband remote for steering and throttle.

The ePropulsion Spirit 1.0 EVO is undeniably more expensive than it’s little sister without the regenerative charging and the cost difference is significant. If you are likely to be doing a lot of sailing and using your electric motor from ship-to-shore in relatively remote locations then the regenration will probably be worth it. For most, though the price differential is probably a little too steep.

ePropulsion Spirit 1.0 EVO specifications

Same as Spirit 1.0 Plus except:
Price: (complete): £2,225
Regeneration: 4 knots – 40W / 10 knots – 300W

Buy it now from epropulsion

Photo: Paul Wyeth

Torqeedo 1103 and Torqeedo 603

Torqeedo was the first company to commercially produce an outboard with an integral lithium battery in 2005. The earliest motors used a high-revving geared motor, which produced a characteristic whine. Following the launch of its new larger battery, Torqeedo changed to direct drive at about the same time that ePropulsion arrived on the scene.

The 1103 is 1.1kW and has a removable battery and tiller/throttle. The battery locates in slots in the powerhead and can be dropped in one-handed, with the slots clearly visible from above, which is helpful in a rocking dinghy. It then hinges back and locks in place with a separate plastic pin. The tiller locates in similar slots.

The two are then connected to the motor by a power cable and a data cable, but the latter has an 8mm plug, with five tiny pins that have to be carefully lined up, then secured with a threaded plastic collar. Neither of the sockets have caps to prevent debris or water getting into them when the cables are not connected.

The display on the tiller shows four lines of data at the same time, which makes them small to read (a phone app can be used for a large display). They include volts, battery capacity, range at a given speed, speed in kts, mph or km/h, and power consumption in watts. A magnetic kill-cord cuts the power circuits if you fall overboard.

The motor has four trim positions to allow for angled transoms, but the split ring securing the locking pin is very stiff and fiddly, especially when you have to adjust it hanging over the transom. A side-mounted lever allows the motor to be tilted horizontally. In normal use a catch prevents the motor kicking up in reverse, but this can be released with another side-mounted lever if you are in shallow water.

Long and short shaft versions are available, with the height of the transom to the top of the prop on the long shaft being 62cm. Clamps screws and fittings are stainless steel, making it suitable for salt water use, but an anode is an extra. It has forward and reverse but not 360º rotation.

Torqeedo 603 specifications

Motor weight: 11kg
Battery weight: 4.2kg (floats)
Battery capacity: 500Wh
Top speed RIB: 4.0 mph
Top speed skiff: Not tested
Thrust: 44lbs
Price (complete motor and 500Wh battery): £1,499
Spare battery: £549

Torqeedo 1103 specifications

Motor weight: 11kg
Battery weight: 6kg
Battery capacity: 915Wh
Top speed RIB: 4.4mph
Top speed skiff: 6.0mph
Thrust: 68lbs
Price (complete motor and 915Wh battery): £2,019
Spare battery: £829

Buy the Torqeedo 603 now from Torqeedo
Buy the Torqeedo 1103 now from Torqeedo

Best Trolling motors

Photo: Paul Wyeth

Haswing Ultima 3

Haswing is a new name to us, but this Chinese manufacturer now has an extensive range of motors, several of which we were able to bring along to our test.

The Ultima 3 has an integral Lithium battery and an output of 1,000W, with the ‘3’ in its name indicating the 3hp petrol outboard its makers claim it is equivalent to. The battery is 600Wh.

The battery was the easiest of all in our test to fit and remove, just sliding down a set of grooves, with contacts in the bottom removing the need for any linking cables or wires, and an easy one-handed operation.

The unit is well engineered, with stainless steel used throughout plus an anode as standard, making this suitable for use in salt water, and a spare anode and shear pin. The tiller/throttle hinges up and down for easy operation and storage. It has a streamlined aluminium leg, but rotates 360º.

A magnetic kill cord is a useful safety feature, and there are 5 LEDs showing battery capacity remaining, but this is the only instrumentation, so there is no way of gauging how much power you are using. It also meant that with no exposed power cables, we could not measure intermediate power settings.

Haswing Ultima 3 specifications

Motor weight: 11kg
Battery weight: 5kg
Battery capacity: 600Wh
Top speed: RIB 4.0mph
Top speed skiff: Not tested
Thrust: 51lbs
Price: (complete motor and 600Wh battery) £1,585
Spare battery: £540

Buy it now from Amazon

Photo: Paul Wyeth

Motorguide Varimax 40

Another trolling motor, this has a claimed 40lb thrust and a variable speed electronic control. The throttle pulls forward for ahead, and pushes back for reverse then twists in the same direction for speed. A clever feature once you get used to it. Ten LEDs show the battery state.

The sliding shaft gives transom heights up to 65cm transom to prop, and 360º rotation. It also quickly tilts through 90º, with 5 positions, for shallow or weedy water.

Clamp screws and fittings are mild steel, meaning you should wash it off with freshwater after using it in the sea.

Motorguide Varimax 40 specifications

Motor weight: 9.1kg
Battery (Sterling 60Ah) – 8kg
Battery capacity: 780Wh
Top speed RIB: 3.2mph
Top speed skiff: 4.0mph
Thrust: 28lbs
Price: Motor £221 / Battery £360 / Charger £100

Buy it now from Amazon

Photo: Paul Wyeth

Haswing Osapian 55

Yachting Monthly’s best budget buy

This is another trolling motor with a claimed 55lb thrust, but with five forward speeds and three reverse on a twist-grip throttle. Again, it is a well-engineered motor, with all fittings and clamp screws made of stainless steel, an anode behind the prop and a spare in the box.

Five LEDs show the battery state. The sliding shaft gives transom heights up to 62cm, and 10 tilt positions.

As with all click-speed throttles you have double the power at Setting 5 compared to Setting 4, and very poor range figures at intermediate speeds compared to motors with electronic throttles.

However it is an excellent value-for- money option for sailors looking for ways to power their tender for short trip

Haswing Osapian 55 specifications

Motor weight: 9kg
Battery weight: (Sterling 60Ah) 8kg
Battery capacity: 780Wh
Top speed RIB: 3.3mph
Top speed skiff: 4.4mph
Thrust: 35lbs
Price: Motor £204 / Battery £360 / Charger £100

Buy it now from Amazon

Photo: Paul Wyeth

Motorguide SW82

Motorguide is a well-established US company that is part of the Mercury/Mariner group. The most powerful of the transom mount range, the 82 has a claimed thrust of 82lbs, and is a 24V unit requiring two 12V batteries in series.

It is also designed for saltwater use, with stainless steel clamp screws and fittings, and a large anode on the shaft. It has an extra long shaft, giving up to 93cm transom height to the prop, 360º rotation, and seven tilt positions There are no battery LEDs. An on/off switch under the control head is the nearest it gets to a kill switch.

Motorguide SW82 specifications

Motor weight: 13kg
Battery weight: 16kg
Battery capacity: 1,560Wh
Top speed RIB: 4.0mph
Top speed skiff: 5.5mph
Price: Motor £1,405 / Batt £360 x2 / Charger £100

Buy it now from Amazon

Photo: Paul Wyeth

Haswing Protruar 1

Another Haswing requiring a separate 12V battery, this has a variable speed electronic throttle, and similar features to the Protruar 5, except no kill cord. It claims to be equivalent to a 1hp petrol motor, but in practice delivered 600W.

The sliding shaft only allows transom heights up to 40cm, but a longer shaft version is available. It has 10 tilt positions and 360º rotation.

Another well engineered unit, with stainless steel used throughout plus an anode as standard, and a spare anode and shear pin. The tiller/throttle hinges up and down for easy operation and storage.

Haswing Protruar 1 specifications

Motor weight: 9kg
Battery weight: 8kg
Battery capacity: 780Wh
Top speed RIB: 3.4mph
Top speed skiff: 4.5mph
Thrust: 40lbs
Price: Motor £320 / Battery £360 / Charger £100

Buy it now from Amazon

Haswing Protruar 5

Another Haswing, the Protruar 5 is the most powerful model we tested. The unit is extremely well engineered, with stainless steel used throughout for the clamp screws and fittings, plus an anode as standard, making this suitable for use in salt water. A nice touch is the spare anode and shear pin in the kit. The tiller/throttle hinges up and down for easy operation and storage.

Its 5 designation indicates its makers think it is equivalent to a 5hp petrol motor, but in reality it delivers around 2.5kW at 24V so requires two separate batteries. It has a variable electronic throttle, three battery state LEDS and a magnetic kill cord.

The shaft slides up and down, giving a maximum transom height of 62cm and 360º rotation. Ten tilt positions are quickly engaged by a squeeze lever.

The thrust was the highest of the test, making it suitable for heavy boats, but the fine pitch prop significantly reduced its efficiency at speed.

Haswing Protruar 5 specifications

Motor weight: 14kg
Battery weight: 16kg
Battery capacity: 1,560Wh
Top speed RIB: Not tested
Top speed skiff: 6.1mph
Thrust: 108lbs
Price: Motor £790 / Batteries £360 / Charger £100

Buy it now from Amazon

Photo: Paul Wyeth

Motorguide R3 45

This trolling motor has a claimed thrust of 45lbs and five forward speeds. The sliding shaft gives transom heights up to 65cm and 360º rotation, with seven tilt positions. Clamp screws and fittings are mild steel, so should be washed after saltwater use.

The click-speed throttle gives non-linear power gaps, with Speed Setting 5 being double the power of Setting 4. This throttle arrangement results in poor range figures at medium speeds compared to motors with electronic throttles, but it keeps the price down.

Motorguide R3 45 specifications

Motor weight:  9.5kg
Battery weight: (Sterling 60Ah) 8kg
Battery capacity: 780Wh
Top speed RIB: not tested
Top speed skiff: 4.1mph
Price: Motor £262 / Battery £360 / Charger £100

Buy it now from Amazon

Minn Kota Endura Max 55

Minn Kota is one of the oldest makers of trolling motors. The Max 55 has a claimed 55lb thrust, with a variable speed electronic twist-grip throttle.

Clamp screws and fittings are mild steel, making it best suited for freshwater, though you can use it in the sea if you wash it off afterwards.

It has a fine pitch prop like all trolling motors, which gives a good static thrust, but efficiency, and hence range, falls off at higher speeds, though the electronic Maximiser throttle helps to offset this.

Minn Kota Endura Max 55 specifications

Motor weight: 9.5kg
Battery weight: (Sterling 60Ah) 8kg
Battery capacity: 780Wh
Top speed skiff: 4.6mph
Price: Motor £480 / Battery £360 / Charger £100

Buy it now from MinnKota

 


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