From: luv2bsailin <luv2bsailin@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Sun, February 13, 2011 11:16:59 PM
Subject: [Electric Boats] Re: Setting expectations
I know I tend to shoot from the hip and toss around ideas just to stimulate discussion if nothing else. It's easy to forget that there are a lot of folks reading these posts and that off the cuff brainstorming comments could be taken any number of ways.
So... where can I find an old dis-masted sailing cat and about 10KW worth of surplus solar panels...
Cheers,
Jim
--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Jim,
>
> I appreciate your information and your candor. This estimate looks better to me if only because you qualified most of your relevant assumptions; location, power requirements, system size, etc.
>
> Since Bill has stated in other posts that "slow speed (5 to 10mph) is ok" with him, it shows that he has different expectations than most of the members of this group. Almost everyone here considers 5kts as "speeding" under electric power, at least for multihour cruising. He's also looking for about 50 miles under power each day.
>
> So here's the question at hand: On a typical 40' x 14' houseboat, can the boat be driven at speeds above 5kts for 50 miles a day on solar power alone? From my calculations, even on a good day, no.
>
> Taking the question all the way back to Bill's first posts. Is a typical 40' x 14' houseboat a good candidate to convert to electric power alone? Considering that most houseboats that size are delivered with well over 400hp installed, reducing onboard power to 20hp or less will probably make the vessel a hazard to navigation in all but the calmest conditions. A mild 10kt crosswind could make the boat unsteerable. So again, from my calculations, even on a good day, no.
>
> I've had some people here say that I shouldn't discourage other people, that I should let them "follow their dreams". But we're the one of the few sources of information about electric boats that isn't trying to sell something. There's not many other places to turn to for answers. I'll heartily encourage people to push the envelope on what an electric boat can do, but the current conversation isn't even close. I love to proven wrong, and I'm always learning new things when research my answers to discussions here. But in my opinion, given current technologies, Bill's concept as originally stated is a non-starter.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "luv2bsailin" <luv2bsailin@> wrote:
> >
> > I forgot to mention that I was using Los Angeles as the location for that 5/2 hour summer/winter figure. Chicago is 4.38/1, Miami is 4.4/2.4. Since NREL uses historical data the typical weather patterns are factored in.
> > Anyhoo, let's say my hypothetical 26x8ft pontoon shantyboat does 5kt on 5hp on a calm day. I've got 200 square feet of brand-new high efficiency panels on the roof. Total peak rated output is 3600W. It's summertime in Miami and I want to take a cruise up the ICW before hurricane season heats up. 3600*4=14,000 is about how much energy I'll be able to get from my PV panels on an "average" day. Let's say about half of that gets wasted between charging batteries and then discharging them to run the motor. That leaves me with 7200 Watt-Hours available for the motor. Converting to "HP-Hours" you wind up with 5HP for a couple hours. So, not accounting for wind and tides, I can cover ten miles a day on pure solar alone. Maybe more if my 50% efficiency number is too pessimistic. It may be, since you'll be sending some of the power directly to the motor during high sun. Hard to say if 5HP-5KT is reasonable either but hey, it's my hypothetical boat so I get to pick the hypothetical numbers.
> > I don't know how this all relates to the hypothetical 40Ft houseboat, being discussed. I suppose it really doesn't much.
> > Cheers,
> > Jim
> >
>
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