Dan,
When I read this paragraph, I thought the same thing,
" When our batteries are fully charged (which doesn't happen every day in cloudy upstate New York) we can run for about eight hours. And our electric motor — designed by an engineer who has built some of the fastest electric motors in the world — can move our 14- ton boat at about 5 mph (even though Bill had projected our top speed on electric power at 3 mph.)"
But if you read it carefully, it does not say that they can run for 8 hours at 5mph.
I found the following info on the "Dragonfly FAQs" page on the "Slow Boat" site.
"Dragonfly has both an electric motor and a diesel engine. Under diesel power, she makes about 6 mph. Under electric power, we usually run at about 3.5 mph. Dragonfly CAN go faster on electric, but drains the batteries much faster at higher speeds"
Unfortunately, I couldn't find a single statement where they declared range/duration and speed at the same time. So I would infer that their half ton battery bank can drive them at 3.5mph for eight hours or about 28 miles. Still impressive, but not 40 miles in eight hours on a single charge. And unlike most of us, they still have a traditionally installed 60hp diesel onboard for long transits and depleted batteries.
This shows the importance of qualifying your performance statements to make them more meaningful to others.
Fair winds,
Eric
--- In electricboats@yahoogroups.com, Daniel Michaels <nov32394@...> wrote:
>
> http://www.slowboatcruise.com/Â They power it for 8 hrs at 5 mph.
>
> Dan
>
> --- On Fri, 8/27/10, Kirk McLoren <kirkmcloren@...> wrote:
>
> From: Kirk McLoren <kirkmcloren@...>
> Subject: Re: [Electric Boats] The future of Electic propulsion
> To: electricboats@yahoogroups.com
> Date: Friday, August 27, 2010, 11:15 AM
> ???
> maybe?
> http://www.off-grid.net/2010/07/12/living-on-a-canal-in-the-great-loop/
>
> “It may be true that you can't fool all the people all the time, but you can fool enough of them to rule a large country.â€
>
> Â Will Durant
>
> From: Daniel
> Michaels <nov32394@...>
> To: electricboats@yahoogroups.com
> Sent: Fri, August 27, 2010 10:30:13 AM
> Subject: Re: [Electric Boats] The future of Electic propulsion
>
> There is a boat on the Great Loop Trawler that goes by electric and diesel. Electric works much better for larger heavy boats. "Electric boats are not speed boats." If you are living on the water and can go slow and when you have power they are very well suited. A generator for a back up would be necessary. Your weight will not be all that much different than carrying 200 gallons of diesel and an engine. Google "The Great Loop". I cannot find the link but it is there somewhere.
>
> Dan
>
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