On Friday I had the pleasure of spending the day on board the Alerion 33 Electric I’ve been following since the first of the year. It was sea trial day and on board with me were the happy new owners Vincent and Margaret Argiro, Ed Saunders, Mastervolt North American service manager and Wayne Burkett, Pearson Composite’s Engineering Manager. My goal was to see how this boat sailed, but more importantly to get a feel for the battery charge life, the noise levels while motoring and to see how well the regenerative capability of the Mastervolt system would work while sailing. Unfortunately much of my video failed due to a memory card issue (my bad), but my report follows anyhow.
The day was perfect, sun shining with a light to moderate breeze. So off we went motoring from New England Boat Works in Portsmouth, RI toward Newport, RI. We were able to easily maintain 6-7 knots of boat speed the whole way under electric motor drive. The amazing thing about motoring on the Alerion is that there is virtually no noise other that what’s being generated by the wind, and the people on board. My in cockpit noise readings came in at an amazing 78dB! I had Ed Saunders check it down below within about 24″ of the electric motor with the engine box cover off. His readings were even lower at 72dB. Oh, and no diesel exhaust odor wafting through the cockpit either, nice. Keep in mind here that the powering design criteria for this boat was in contemplation of a small crew of two, not the boat load we had. As for the noise issue, most folks really don’t understand my dB values, so let me elaborate just a bit. I’m extremely sensitive to noise and I’ll bet I’m not alone. Our lives are full of noise, and I’m convinced it has a physiological impact on my ability to relax on board a noisy boat. Look over the charts below to get a feel for your daily noise exposure and you can begin to get a feel for what I’m talking about. Also consider this, in my sound emission tests on conventionally powered cruising sailboats as a judge for Cruising World magazine’s Boat of the Year competition in 2008, I recorded sound levels of between 82-98 dB at similar cruising speeds to what we were achieving on the Alerion.
City traffic, inside car……80dB
Level at which long exposure may result in hearing loss…90-95dB
You get the idea, noise is your enemy!
So what about the electrics? Again design criteria are important considerations when we analyze the suitability of this system on a sailboat. First, Vincent wanted to have the ability to motor 3-4 hours. The boat is after all a sailboat, and his needs dictate that he have the ability to motor to and from his berthing area, as well as to have power available in a no wind situation. It’s important to remember that the boat itself falls into a fairly new category of elegant “day sailors”, so extended range is not really a consideration. Two of Mastervolt’s lithium iron phosphate batteries with 160 amp hour capacity each are the heart of the system, powering a 7.5 kW AC motor. (The DC from the batteries is converted to AC in the motor controller.) Did we meet the design criteria? You bet, and with some extra time to spare. One of the advantages to the Mastervolt batteries is that unlike conventional battery technology, which have historically limited deep cycle capability to 50% of capacity to ensure long cycle life, these batteries are capable of deep cycling up to 80% of their capacity. This represents a 30% gain and effectively increases their power density as a result. There are other lithium chemistries in use with greater power density, but Mastervolt chose the lithium phosphate chemistry because it is comparatively much safer and not prone to the thermal run-away issues we’ve all heard about relative to lithium ion batteries. This is an important differentiator in a marine installation and has been a cause for much worry in my role working for the industry Standards writing body, ABYC.
What about battery recharging? Again, Vincent has some specific design limitations. The Mastervolt batteries are capable of accepting very rapid re-charge rates, but in Vincent’s case he has a dock with only 30 amp service available and he has to share that with another boat. His share represents approximately 16 amps. The Mastervolt chargers used in this system are fully programmable to adjust their current draw, and have been calibrated to accommodate this short coming. Expected recharge time when plugged in is engineered in this case at 2-3 hours. It could be ramped upward with more available power. Of course the boat also has re-charge capability when sailing as well. By putting the boat in reverse gear the spinning propeller will regenerate power while underway. This was the one fine tuning adjustment that had not been maximized last week. A new feathering propeller had been installed the day before our trial, so some additional tweaking will need to be done. I have no doubt that with the Mastervolt system, which allows for computer interface to both monitor and adjust all of the various parameters of this system that issue will be resolved in short order.
So, now the boat will be off to its new home in British Columbia, CA. I wish Vincent and Margaret the best of luck with their new boat. It’s a game changer in my view, and going to the perfect home. Vincent is extremely technically minded and will be totally diligent in gathering ongoing data; to him this is the ultimate science project. So, far, he, Mastervolt and Pearson Composites are scoring an A+. I will get back in touch as the summer progresses to get some follow-up reports on this boat. I love the concept, and really want it to work! By the way, the Alerion is a sweet sailor too!