If you're tired of the smell of gas and the constant maintenance of a small engine, you might want to convert outboard to electric and finally enjoy some peace on the water. There is something truly special about gliding through a lake or a quiet cove without that constant thrum-thrum-thrum of a two-stroke engine vibrating through your teeth. Plus, let's be honest, cleaning carburetors is nobody's idea of a good Saturday.
Converting an old gas-guzzler into a clean, quiet electric machine isn't just for tech geniuses or engineers. With the right parts and a bit of patience, almost anyone can do it. It's a great way to give a second life to an old boat motor that might otherwise end up in a scrap heap just because the powerhead gave up.
Why Bother With a Conversion?
You might wonder why you'd bother to convert outboard to electric instead of just buying a brand-new electric motor from a shop. Well, for one, those purpose-built electric outboards can be incredibly expensive. We're talking thousands of dollars for even a modest setup. By using a "donor" outboard, you're saving a ton of money on the housing, the mounting bracket, and the lower unit.
Then there's the environmental side of things. No more worrying about oil leaks or gas spills in the water. Most electric setups are practically maintenance-free once they're installed. You charge the battery, flip a switch, and you're gone. No pulling a starter cord twenty times until your shoulder hurts.
Finding the Right Donor Motor
The first step in the process is finding a good donor. You're looking for an old outboard where the engine is dead but the "leg" (the lower unit and propeller) is still in good shape.
What to Look For
Check the gear housing. You want to make sure the propeller spins freely and that the gears aren't ground to dust. If you find an old 2-hp to 5-hp Evinrude or Johnson from the 70s or 80s, you've struck gold. Those things were built like tanks. Since you're going to rip out the entire internal combustion powerhead, it doesn't matter if the pistons are seized or the fuel lines are rotted.
Weight and Size
Don't go too big for your first project. A small 2-5 horsepower equivalent is much easier to manage than trying to convert a massive 40-hp beast. The bigger the motor, the more expensive the batteries and the motor controller will be.
The Basic Components You'll Need
To successfully convert outboard to electric, you need three main things: a motor, a controller, and a battery.
- The Electric Motor: Most people go with a brushless DC (BLDC) motor. These are efficient, powerful, and relatively small. You'll want something that matches the RPM range of the original gas engine so you don't have to swap out the propeller.
- The Controller: Think of this as the brain. It tells the motor how fast to spin based on how much you turn the throttle.
- The Battery: This is where the real cost lives. Lithium Iron Phosphate (LiFePO4) is the gold standard here. They're lighter than lead-acid batteries and last way longer.
How to Do the Conversion
Once you have your donor motor, it's time to get your hands dirty.
Stripping the Powerhead
First, you'll need to remove the top cowling and start unbolting the gas engine from the midsection. You'll be removing the fuel tank, the carburetor, the spark plugs—basically everything that makes it a gas engine. What you're left with is the mounting plate and the driveshaft sticking up out of the leg.
The Adapter Plate
This is the "custom" part of the job. Since your new electric motor won't have the same bolt pattern as the old gas engine, you'll need to create or buy an adapter plate. Usually, a thick piece of aluminum works best. You'll bolt the electric motor to this plate, and then bolt the plate to the outboard's midsection.
Connecting the Driveshaft
You'll need a way to connect the electric motor's output shaft to the outboard's driveshaft. Most DIYers use a simple shaft coupler. It's vital to get this perfectly aligned. If it's even slightly crooked, you'll feel a ton of vibration, and you'll wear out your bearings in no time.
Let's Talk About Batteries
Batteries are the heart of the system when you convert outboard to electric. If you're just doing short trips around a small pond, you might get away with a couple of deep-cycle lead-acid batteries. They're cheap but heavy.
If you want to actually spend a few hours on the water, you really should look into Lithium. A 48V Lithium setup will give you plenty of "juice" without weighing down the back of your boat. Just remember that water and electricity are famously bad neighbors. Make sure your battery is in a waterproof box and that you have a high-quality fuse or circuit breaker in the line.
Wiring and Throttles
You can't just hook the motor directly to the battery, or it'll just spin at 100% speed until something breaks. The controller sits between the battery and the motor.
Most people like to use a "twist-grip" throttle, similar to what you'd find on an electric bike or the original outboard. You can often adapt the original tiller handle to house the new electric throttle components. It keeps that classic "boat feel" while controlling a modern electric system.
Performance: What to Expect
Don't expect to win any races. When you convert outboard to electric on a budget, you're usually aiming for displacement speeds—roughly 4 to 6 miles per hour. It's perfect for trolling, bird watching, or just moving from the dock to your favorite fishing spot.
The best part is the torque. Electric motors have full torque the second you turn the handle. It's a very different feeling from a gas motor that has to "rev up" to get moving. You'll find that the boat moves almost instantly when you give it power.
Keeping Things Cool
One thing people often forget is cooling. Gas outboards use a water pump to move lake water through the engine. Electric motors get hot too, but they don't always need a water jacket. Many small 1kW or 2kW BLDC motors are air-cooled. However, if you're pushing a lot of power, you might want to look into a water-cooled motor and use the existing water pickup in the outboard's lower unit. It's a bit more complex, but it ensures your motor won't melt on a hot summer day.
Is It Worth the Effort?
Honestly, it depends on what you want out of your boating experience. If you love tinkering and want a project that results in a unique, functional piece of gear, then yes, it's absolutely worth it. There's a certain pride in pulling up to a dock and having people ask why your motor isn't making any noise.
On the other hand, if you just want something that works right out of the box and you have the cash to burn, you might be better off buying a pre-made electric motor. But for the rest of us who enjoy the DIY life, to convert outboard to electric is one of the most rewarding weekend projects you can take on.
Final Thoughts
The shift toward electric propulsion is happening whether we're ready or not. By converting an older unit, you're participating in a bit of "upcycling" that helps the environment and your wallet. It's quiet, it's clean, and there's no more oily residue on your hands at the end of the day.
Grab an old wrench, find a donor motor on Craigslist or at a yard sale, and give it a shot. You might be surprised at just how easy it is to leave the gas can behind for good. Once you experience the silence of an electric motor on the water, you'll probably never want to go back to gas again.