ELECTRIC PROPULSION: SOME THOUGHTS ON ELECTRO-SAILING. PART ONE

I was awakened from my mid winter doldrums by an email from a fellow who had some questions about electro-sailing if he were to convert to electric propulsion:

"My wife and I are looking at converting our Vancouver 27 to electric. I think electric with approximately 200 amp hour 48v bank would meet all of our needs under normal conditions, but because there may be rare occasions

but because there may be rare occasions, like if we have to transit a canal the like Erie Canal, where we would need to motor for an extended period I am I am trying to determine if a small generator like the 2000i would be suitable to propel the boat at a slow speed for extended periods.

You stated that you could motor at about 3 knots with your 2000i generator. What charger do you use? Have you done this for several hours at a time? I am curious if you have experienced issues with heat build up, or other problems that might be an issue with extended use of the charger to power the electric engine."

These are great questions and ones I wondered about back in 2007 where I began to get serious about converting to electric propulsion. So I thought I'd make a blog post about my experience over the past nine seasons with electric propulsion and electro-sailing.

1) I am trying to determine if a small generator like the 2000i would be suitable to propel the boat at a slow speed for extended periods.

The answer is yes. I have found I don't really need to do it often but I have had to at times  motor up to 40 nautical miles just using a Honda 2000i generator and battery charger to move my 30 foot boat along. An example of such a day is shown in this video:

Again I have not had to do this often since at some point during most sailing days a breeze does kick up at some point. But, even if it does not I find electro-sailing with Electric Propulsion to be much quieter and much less vibration than when I had a diesel which makes for a much more pleasant day on the water.

I'll get into more specifics as to the components used on BIANKA for extended electro-sailing  and the things you need to know to make it possible in the next post.

CHOICES: Batteries

I was looking around for some specs for battery terminal torque specs and came upon this chart at the MK Battery site:

I'm about to start my seventh season with the four 8A4D AGM batteries that make up my 48 volt electric propulsion bank. Somehow I instinctively used them in a way that should provide over a thousand life cycle charges.  I typically revert to Hybrid mode using the Honda 2000i generator once the battery bank has dropped to 70 to 80% from 100% full charge.  Turns out that looks like a good point to have a good charge life cycle for the bank.  So far so god. I still think I made the right decision in going with AGM batteries over the Lithium Ion batteries that were still fairly new back in 2008 when I did the conversion. The cost and availability were factors I considered. Today I think I would still go with the AGM's as they seem to be holding up well. I'll do some more in depth battery testing in a few weeks to see how well.    The following video is and example of my modus operandi using electric propulsion and when I operate in hybrid mode on an unusually windless day heading down the Hudson River:

END OF THE SEASON THOUGHTS OF AN ELECTRIC SAILOR: 2011

It's that time of year when I look back on how my electric propulsion system did during the past season. Once again I was surprised by it. When I decided in 2007 to repower with an ASMO MARINE Thoosa 9000 system. There were no boats that I knew that had done this and I thought long and hard about it before making the leap. But, after four years of operational experience I'm still very glad I did. The fourth season will stand out because of two firsts that occurred. One was an extended day of motoring. About ten hours to be exact. A rare day here around the Isle of Long when hardly even a whisper of a breeze filled the sail. So after starting out early and motoring under battery power for a few hours I carried the Honda away from the cockpit and fired it up. I could never do that with the old diesel. The noisy diesel was always right below the cockpit vibrating away making for a noisy afternoon of motoring. Fatiguing too! My day of extended motoring was much more pleasant experience with electric propulsion.

Another first I discovered quite by accident was that BIANKA can actually regen power back to the battery bank. I discovered this while electro sailing moving along at about 6 knots. I had earlier in the season decided  that the best way to operate  under sail was to slightly turn the prop under power. This will negate any prop drag when sailing and therefore increase boat speed. Sounded like a good plan and it uses minimal power from the battery bank and no need to buy a folding prop. But, as I found out that if the boat speed under sail starts touch around 6 knots it also starts recharging the battery bank.


 This is known as "regen" where the prop starts to turn the motor backward and it starts operating as a generator. It's not a lot at the low end but, you really don't want a lot charging because you don't want to take a chance on overcharging the battery bank.  I'm looking forward to next season and hope to experience more days where I can see the regen in action. So even after four years my boats electric propulsion system still had some pleasant surprises left to show me.

HORSEPOWER AND SAILPOWER

Bob at BOAT BITS has some interesting numbers and comments regarding sails and the amount of horsepower they provide to a sailboat.  Including some French perspective on motoring and sailing:

"The French, who know a thing or two about sailboats, call motorsailers "50's" (seldom used as a positive) to designate that they share sail and power at a 50% ratio. These days, with cheap HP available, nearly all modern sailboats would qualify as motorsailers... Something to keep in mind."

I'll say! Which may explain this scene that I came across more than a few times in my cruises this summer:

MAST DOWN, MOTOR ON!

Bob over at BOATBITS had not posted for a few days which was unusual for him. But, I assumed he had been off on a sail. I was partly correct. His CAL 34 was demasted as he sailed "toward" Antigua. After he cut away the mast he turned on his electric motor and headed to Saint Criox for repairs. Here is the money quote:

"The motor to St Croix was uneventful, if a bit slow, but we made port with battery power to spare thanks in no small part to our Electric Yacht drive and Honda generator as they ran for twelve hours without a rest in really big sloppy seas and just seriously all around kicked some serious butt!"

While it's sad to read about the demasting. The good news for those of us with electric propulsion systems is that his electric motor did the job of getting the boat to St Criox for repairs in less than ideal conditions.