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    • I became fascinated with the story of Andy Rebele, whose company is designing electric powertrains for boats. We had a chance to ride in a classic wooden boat fitted with Andy’s re-imagined outboard, and it felt like the future of boating. No smells, no noise, no vibration. 

      Here is our conversation. Jump in and ask questions.

      So Andy, your business is outboard motors & batteries to fit existing boats. Is that right?

    • That's right. The mission is to drive a new era in boating — one that’s more enjoyable, accessible, and environmentally friendly. 

      We have a unique opportunity in boats that doesn't exist in cars or motorcycles where there's a separate market for the powertrain, so we focused on the outboard motor. Outboard boats have grown to 80% of the boat market by unit volume.

    • One reason is that EPA pollution controls are concentrated on non-outboard boats. They contracted with Mercury Marine to see if it was practical to put catalytic converters in outboard motors and Mercury concluded no, it’s not practical.

      Some boats in the gray area that could have chosen inboard or outboard have gone outboard to get out of the requirement for catalytic converters.

    • Fascinating! Is that also scary?

      My recollection of outboard motors is many were so-called two-stroke engines, which were also smelly because they burned oil with the gas and gave off a blue smoke.

    • The smell didn't just come from the oil. The smell is partly because at least 25% of the fuel comes out the exhaust unburned in that kind of engine.

      My friend had a two-stroke ski boat with a 180-horsepower engine that burned 18 gallons per hour at full throttle. So every hour he was leaving 4.5 gallons of un-burned gasoline in the lake.

    • Now most of them have gone to four stroke to meet stricter EPA pollution requirements, but not in many other countries. However, no outboards have catalytic converters, so all of them are putting out 10 times the cancer-causing pollution per gallon of a car.

    • This puts into perspective my trip to Wisconsin last month where a local youth waterski club was performing behind several 500 horsepower outboards. There were lots of kids behind those boats and houses on the lake. You’d think there’d be a huge demand to put out less pollution.

    • You’d think so.  

      There’s an evolution that happened in boating: from the turn of the century they had a tough time getting powerful motors for boats so they had to make really efficient hulls. The rapid advance of cars, especially around World War II, meant they had these extremely powerful motors they could put in boats. So hull evolution went backwards because no one was selling boats with EPA stickers touting efficiency because they could make up for inefficient hulls with big motors.

    • That's right. It has an inverted V. So instead of the the deep part of the V going down the center of the hull, the deepest part is on the sides, with the shallowest point in the center. The wake from the sides is washed toward the middle so the stern rides up on a water and air mixture to give the boat lift, which makes it a lot more efficient.

      It’s called the Sea Sled and when we’re planing, it looks like it’s skimming across the water.

    • My impression of the motors that you're designing is they’re on the lower horsepower side. Are you starting modest and working up?

    • The literal horsepower of our motor is 26.8 and we'll be raising that soon. But the effective horsepower is around 40 because we can use a lot more efficient propeller than the gas outboards can.

    • Gas outboards have a very narrow RPM range in which they have good torque, toward the top end of their RPM range. At low RPM they have very poor torque. 

      Since these outboard motors don't have a clutch, when you put them in gear and you have a big propeller, it takes a big bite on the water. It would be like trying to start your car in third gear — the motor would stall. So they use smaller propellers that don’t stall at low speed, and some even use tactics such as having holes drilled in the cylinder of the propeller to let exhaust come out to make the water softer, but all of these measures make them less efficient at higher speeds.

      We can use the actual theoretical right propeller for our higher speeds, where most of the energy goes.

    • What we do is select a hull for which our motor is a good fit, determine the top speed, and find the gas outboard that makes the hull go the same speed. That’s usually about a 40 HP gas outboard.

      We're going to have a different equivalency at different speeds. We picked 15-20 mph for our equivalency test because it seems like the speed our customers are most likely to go. We try to be honest but keep it simple.

    • I've been in boating since I was a little kid when I grew up in San Diego County.

      I would go out every weekend and go fishing on Otay Lake with my dad and sometimes just with a friend. On special occasions, my dad would rent a little aluminum boat. About a year ago, I went back during a tour for a Bass Pro who's using our boat. It seems like they’re renting the same aluminum boats powered by about the same outboards they had when I was a little kid.

    • But even while I was doing that adventure in Silicon Valley, in the mornings I was rowing with a team out of Stanford Rowing Club and raced the Henley Regatta in England.

      And even before that when I was in grad school at MIT, I was the Freshman rowing coach for Boston College. So I was going out every day in a little aluminum boat with an outboard motor and experiencing all of the pain of being a user. It was horrendous.

      Rowing is an aesthetic sport—you're out on the water, the scenery is beautiful, the rowing is beautiful. The only ugly thing about the day is the obnoxiously loud motor behind you.

    You've been invited!