Charging Ahead: Why Electric Boat Motors Are Closer Than Ever to Breaking Through

The Elco 50 electric outboard with helm steering

Is it the end of gas outboards? Electric motors are primed to break through, even if we're starting small.

About five years ago, I did a review of the electric boat market and summed it up this way:

Performance, Range, Price – pick any two. The boating market was still a long way from going electric and electric offerings were coming up short on at least one of the three things every boater wants. But what about today? Have we resolved the key issues that have held back battery powered boats?

Before answering that question, let's look at whether electric powered boats are something we really want in the first place. The most important benefit to an electric powered boat, in my opinion, is the low maintenance. Reciprocating gas-powered motors, especially outboards, are incredibly complicated machines and require ongoing maintenance such as impellers, filters, and oil changes, as well as costly fuel to operate. The convenience of simply dropping a freshly charged battery into the shaft of an outboard motor before leaving the dock is very appealing. High torque and silent, smooth operation score some very important additional points. But the maintenance factors alone can justify a market swing to electric, provided today’s manufacturers can deliver on the three important things: performance, range, and price.

Performance has traditionally never been something we traditionally associated with electric powered boats. I recall testing electric boats that could best be described as picnic boats to be used on short trips around the summer home while running at a top speed of 5 mph. Not today! A good example of electric outboard performance improvement is the Evoy Storm. At an equivalent to 300 horsepower, it is proof that electric outboards can equal the power of a reciprocating engine. But while performance can clearly be achieved today, the majority of manufacturers are currently prioritizing motors for lighter, smaller boats that call for lower horsepower. This is because higher horsepower reduces the range today’s batteries are able to deliver.

The question of range is more complex. It is also the most important for electric motor manufacturers. The most common concerns among electric buyers today involve range anxiety, long charging times, and thermal management issues. Boaters with electric outboards must learn both how to drive the boat and how to conserve the battery. Running an electric boat at full throttle will drain a battery quickly, yet running at half throttle will typically more than double the available range. This makes it difficult to accurately predict how far you can comfortably travel from your charging location. An interesting idiosyncrasy of electric boats is that over some specific throttle settings, you may not actually increase speed at all – you may just be wasting any power that you add. Every boat/electric combination needs to establish a specific sweet spot for maximum range. For outboards, several electric manufacturers recommend buying a back-up battery that can be carried on the boat and dropped in when needed, effectively doubling your range.

Batteries have long been the key to transportation applications and this applies to the marine industry as well. Lithium solid state batteries promise many advantages over batteries using liquid organic carbonate electrolyte, but there is a problem manufacturing these batteries. The problem is simply this: While solid electrolytes enable the use of lithium metal anodes in order to achieve higher silicon loads and improved stability, solid electrolyte does not fill all spaces to provide complete contact as well as a liquid does. Predictions range from one to three years before we see batteries that can resolve this concern. Nonetheless, we can still say with some confidence that range is not quite the serious problem that it was, providing you know your boating requirements and consult with the manufacturer before buying.

This answers two of our concerns with electric powered boats, so what about number three? Price.

With the many advantages of electric over gas, I don’t believe electric outboards need to be cheaper than gas to justify buying them. Most will carry a lower MSRP than your gas motor but remember that battery options add significantly to the baseline price. Most electrics come with a comparable two year warranty. Few currently have a knowledgeable dealer around the corner.

The Elco 50 hp electric outboard

One solid reason that we can be certain of a bright future for electric outboard motors is that every one of the major outboard manufacturers is already producing them. Mercury presently has Tohatsu building their 30 hp and below gas outboards. It seems logical to me that once electrics are fully accepted by the slowly evolving boating market, Mercury will switch to making their own small motors – using their electrics to make the switch from the current Tohatsu-sourced gas engines. Yamaha is selling and expanding their electric outboards under the Harmo name, while Tohatsu sell their electrics under their fast growing Alaris brand. Honda, the company that pioneered four stroke outboards, are developing prototypes for several electric horsepower levels and are set to release their first electric outboard this year.

While it is difficult to directly compare a reciprocating gas outboard to an electric outboard, let's look at some of the numbers that demonstrate how far electrics have recently advanced. I compared a Mercury 50 horsepower gas outboard, to an equivalent 50 horsepower Elco electric, with both mounted on a 16’ semi-V fiberglass boat. The numbers are approximate and can vary, of course.

There is a significant number of smaller new companies actively pursuing electric boat motor opportunities. Here is a partial list: Mercury-Avator, Yamaha-Harmo, Torqueedo, epropulsion, Stealth, Elco, Tohatsu-Alaris, Rad Propulsion, Evoy, Suzuki, Acel Power, and Vision Marine.

The Evoy Storm 300 outboard with Axopar's AX/E Boats

Boaters who switch to electric from gas powered outboards will encounter a gentle learning curve. Providing a few truisms might be helpful. When choosing between long and short shaft, choose long to avoid cavitation. Compared to gas power, electric outboards run their props at lower RPMs but deliver more torque. When choosing a battery, either buy the largest offered or buy a second battery as back up. Factor these details into your cost when deciding what to buy. Speak with a tech at the motor company to confirm the motor you want matches with your boat. And when you are using a new electric motor, keep an eye on the electronic gauges and remember that it is best to not to let the level of charge go below 60% if possible.

The electric boat market seems primed to break into the mainstream and leave some of the lesser known brands behind. Be ready and receptive to the advance. As for myself, I am going to clamp three of those 300 hp electric outboards on the back of a 38-foot offshore and show some of these gas guys who’s boss.

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