We believe that it's important to be transparent about electric boats and what uses they're suitable for. Given the limitations of battery and electric boat engine technology, certain boats and how they're used aren't great candidates for an electric engine repower. The big center consoles that run off shore to go tuna fishing might have to wait a few years before they can switch to electric outboards, but there are plenty of other boaters who can expect their boat to perform the same or better after switching over to an electric outboard or electric inboard engine.
It's hard for me to think of a better candidate for an electric outboard repower than a sailing coach boat. Before EMO Electric came along, I spent over 10 summers teaching people how to sail at the Westhampton Yacht Squadron (WYS). In short, sailing coach boats are great for an electric outboard repower because they typically return to the same dock each night, aren't on the water for very long, and typically run at low speeds. When they operate at high speeds, it's usually for a short period of time. This is important because electric boats consume exponentially more power while they're up on the plane. For instance, our electric Boston Whaler has a run time of about 30 minutes up on the plane, and about 7 hours at 4 knots.
We're planning to have hard data from an actual electric boat on the water for our Use Case Series in the future. But, given that it's February and there isn't much sailing happening on Long Island, this example is hypothetical. That being said, it's backed by the data we've gathered from our own electric boat, a 13' Whaler with Pure Watercraft's 50hp electric outboard.
For this example, we'll assume that WYS repowers one of their 13' Boston Whalers using Pure Watercraft's 50hp/25kW electric outboard with one 8.8kWh battery, just like our 13' Boston Whaler. With one person aboard, run time on the plane is about 30 minutes. At 4kts, the run time is about 7 hours. We'll also assume that WYS installs 220v power to charge their electric boat at their dock.
At WYS, their 13' Whaler is primarily used to coach Optimist (Opti) lessons. Optis are small, bathtub like boats designed for kids. They're only about 8ft long and don't go particularly fast, but they're great for learning and are probably the most successful one design fleet in the world. There are a lot of Opti coach boats out there, and soon, we think that there will be a lot of electric Opti coach boats on the water!
Opti lessons at WYS are from 9am-11:30am and 12:30pm-4pm, with an hour in between for lunch. We'll assume that the coach remembered to charge the electric boat the day before, so the lesson begins with the battery at full charge. Class begins at 9am, and after the boats are rigged and the land lesson is complete, the electric Whaler hits the water at 9:45am. The Optis sail right in front of the club around a small course. During most of the time on the water, the electric boat is moving at less than four knots, and is often drifting in neutral. Occasionally, the coach has to get the electric boat up on the plane to chase down some Optis that have sailed away from the course. After an hour and a half on the water, the electric coach boat returns to the dock at 11:15am with about 65% charge.
When the electric boat gets back to the dock at 11:15am, the coach plugs in the 220v charger, which charges the battery until 1:15pm, when the coach leaves the dock in the afternoon. At 220v it takes three hours to recharge Pure Watercraft's battery, so after two hours the battery is easily back to full charge. Even if the battery had been run down to 33%, the electric boat would still be topped up by the afternoon lesson!
At 12:30pm, the afternoon racing class begins. The first 45 minutes are spent rigging the boats and discussing the drills that'll be practiced on the water. By the time the electric coach boat hits the water at 1:15pm, the wind has picked up, and the racing students are all over the bay. During 15 minutes of the lesson, the electric Boston Whaler is up on the plane, running around between the front and the back of the fleet, which eats up 50% of the battery's charge. For half an hour, the electric coach boat is anchored while the racing class sails around a small course, and no energy is consumed by the electric outboard. For an hour and a half, the electric coach boat is moving around 4kts. At this speed, Pure Watercraft's electric outboard burns about 14% of its charge per hour, so about 21% of charge is used during this hour and a half.
When the coach brings the electric boat back to the dock at 3:30pm, her electric outboard still has 29% charge remaining. She plugs it in and the electric Whaler is ready to go for the next day's lesson!
Throughout the day, there were no direct emissions from the electric coach boat. Actually, there weren't any emissions at all, given that WYS has solar panels on their main clubhouse! The students and the coach saved their voices since they weren't yelling at each other over a loud internal combustion outboard all day. WYS also saved on the cost of fuel throughout the summer, and didn't have to spend any money on maintenance, oil, fuel filters or winterization.
An electric coach boat might not work for every boat at every yacht club. Some clubs tow large distances for regattas, and sailboats larger than Optis require the coach boat to spend more time moving at high speeds. That being said, it is important to keep in mind that the numbers above only reflect one battery, and a 13' Boston Whaler could easily handle the weight of an additional 8.8kWh battery, which would double its run time at all speeds. As the example above proves, an electric coach boat will work for many lessons at many yacht clubs, and has some excellent advantages over an internal combustion engine.