When it comes to electric outboard motors in a boat, people like the environmental friendliness, the convenience, the responsiveness. They love the super-quiet operation and the lack of maintenance requirements. But whether it’s because of stories they’ve heard from early adopters of electric motors from years past, articles about range anxiety with electric cars, or just unfamiliarity with modern lithium-ion batteries and their capacities, one concern still looms. Many people are afraid to take the leap to electric motors because they perceive the range to be so low that there’s a high likelihood they’ll get stranded out on the water.
When we exhibit at boat shows, the most common question we’re asked is “what’s the range?” It’s never a straightforward answer, and difficult to cover all the nuances to a passing prospect. I’ll try to cover the whole story here, but keep in mind that depending on when you’re reading this, the story may be somewhat different as battery technology is constantly changing (for the better).
Good Planning is Still Required
The first point to note is that electric outboard motors share one attribute with their gas counterparts: you are bringing a limited supply of energy to power your motor. In the case of an electric motor, it’s not a physical substance (and not something that burns, is smelly, or pollutes the air and water) but there’s a finite supply on your boat.
In years past, I’ve run out of gas on the water more times than I’d like to admit. In each instance, I received a friendly tow back to the marina or got a couple of gallons of gasoline from a towing service or a good Samaritan with a jerry can.
The common rule that boaters rely on is the rule of thirds: Use a third of your fuel to get to your destination, a third to get back, and always have a third in reserve. The same holds true for operating your electric outboard, and this emphasizes the proper planning is still important.
Of course, if your plans change (or your calculations were incorrect) and you require a premature refuelling, electric motor owners will be faced with a several-hour delay while they wait for their battery to recharge. Fair enough. This can be mitigated somewhat by use of a fast charger, and we recommend everyone have one (not to use all the time it’s not good for your battery life, but indispensable for those times when you really do need to charge fast).
Can I Go as Far With an Electric Motor as I Can With a Gas Motor?
A typical 3.5 hp four-stroke gas motor has a 1.1L (0.5 gal) fuel tank, which will allow the motor to run at full throttle for about 50 minutes when full. Therefore, you’ll go farther (at 75 minutes of runtime at full throttle) with a Spirit 1.0 Plus or Evo. It’s true that you can have an external fuel tank elsewhere in the boat (taking up space), but it’s also true that you can augment the integrated battery with an external battery. Given the much higher energy density of lithium batteries, a much smaller and lighter battery will get you more range than an external fuel tank.
To summarize, like with a gas motor your range is a factor of how much fuel (energy) you bring with you.
So What’s the Range?
This is a difficult question to answer because, like with gas motors, it depends on so many factors: battery size, travel speed, wind speed and direction, current, hull shape, weight of the boat, etc. It’s like asking “how long is a piece of string?”
What is easier to answer is how long (in hours or minutes) you can operate an electric outboard with batteries of different sizes. How far you’ll go will while it’s running will depend on those factors above, but we can offer some examples and guidelines. For example, an eLite will run for 45 minutes, transporting an 8 ft aluminum boat about 5.6km (3.5 miles) on a full charge at full throttle (going about 7.5 km/h or 4.7mph) on calm lake water. A Spirit 1.0 Plus will run for 75 minutes, taking you about 12.5 km (7.8 miles) on a full charge at full throttle (going about 10 km/h or 6.2 mph) on calm lake water. Another figure we like to quote is that you could expect a 36-mile range (22 miles) if you drop the speed down to 7.1 km/h (4.4 mph). You could easily go fishing all day at trolling speed.
Of course, one rarely travels with the throttle wide open the entire time, so your actual range will typically be a lot higher than the figures quoted above.
Electric Outboard Motor Use Cases
On the surface (pun intended) the range of a small electric motor seems to pale in comparison to a typical small gas outboard. Keep in mind that the intended use cases for the eLite and Spirit models are not to serve as the primary propulsion for power-driven pleasure craft. They also can’t match the speed that a larger gas motor (9.9hp to 50hp) is capable of. You won’t be planing your boat with an eLite or Spirit electric motor.
While it’s certainly possible to have an electric outboard the the power output you need for that (up to 53hp equivalent, with electric inboard motors capable of even greater power), the cost increases significantly and it becomes less easy to justify the versus an equivalent gas motor.
The smallest electric motors are ideally suited for small boats—tenders, dinghies, RIBs, SIBs, jon boats and other small fishing boats. Small and medium-sized (up to 3,300lbs) sailboats are also perfect candidates.
Good uses cases include ship-to-shore travel, fishing, leaving and entering the marina and electric-only lakes. All of these are applications where long range and high speeds are generally not necessary.
How do I Maximize the Range?
That’s a great question, which we cover in a separate article.
