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Re:electric drive for a tunnel stern?

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  • sals_dad
    First, check out the Yahoo Electricboats forum. Lots of intelligent discussion of electric propulsion. It has come a long way, but the limiting factor is
    Message 1 of 15 , Feb 17, 2007
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      First, check out the Yahoo Electricboats forum. Lots of intelligent
      discussion of electric propulsion. It has come a long way, but the
      limiting factor is still the very low capacity of lead-acid batteries
      (compared with, say, a gallon of gasoline)

      But for auxiliarry propulsion of a small sailboat, it might be just
      the thing.

      If I were you (and in fact I AM you - with a 21' sharpie that can't
      beat worth a d*&^, beautiful quiet shallow waters with strong
      currents...) I would (did) spend $300 at WalMart on a biggish Minn-
      Kota trolling motor and a couple biggish batteries, and start messing
      around. Add solar, generator, bigger batteries, etc as you think you
      need them.

      If you find the propulsion system meets your needs but your sailboat
      doesn't, THEN think about a new hull.

      Efficiency of electric? - as of today, it would be very difficult to
      assemble an electric system as efficient as you can get with gasoline -
      whether you measure efficiency in miles/dollar, miles/lb of
      mechanical and fuel carried, miles/lb carbon burnt, whatever - unless
      you can find a sweet spot of low usage, and high solar/wind charging.
      The big advantage of electric in boats is the quiet...

      Sal's Dad


      > I was on my 23 ft trailer sailor, but due to the narrow channels,
      > contrary winds and a boat (bless her heart), that doesn't tack worth
      a
      > hoot, we spent 100% of time listening to the two stroke.
      >
      > So what I think I need, is a 25 foot, easilly driven, room for two,
      > electric powered boat....
    • derbyrm
      Many years ago, the editor of Analog Science Fact & Fiction, mused on the several forms of efficiency: - miles per gallon - miles per dollar - watts per pound
      Message 2 of 15 , Feb 17, 2007
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        Many years ago, the editor of Analog Science Fact & Fiction, mused on the several forms of efficiency:

        - miles per gallon
        - miles per dollar
        - watts per pound
        - watts per cubic foot
        - watts per milligram of pollutants emitted at point of use
        - watt-seconds per dollar of maintenance costs

        People have suggested that we should use hydrogen fusion for power, like the sun does, but the sun's efficiency is something like one horsepower per cubic mile. (It's been a long time since I saw the actual figure.) Parking/docking such a vehicle would be difficult.

        When we select a power system we unconsciously make a lot of choices on prejudice and then argue over some quantifiable thing like mpg. Sure, electric power is clean at point of use, but the total emissions for the system may be lousy; e.g. did the battery get charged by an old coal burning power plant? How long before the wind farms or solar cell arrays make a noticeable change in the weather? Land is about $10,000 per acre here in Southern Indiana, but up in the Chicago area, that money would buy only a few square feet. Electricity cost is primarily transmission cost, so don't talk about the square miles of desert out west.

        I once spent several hobby years designing a modern steam car. Burns anything, as clean as you want to make it, full torque at zero rpm, quiet, and the Stanley Brothers built the best. (It failed for psychological and marketing reasons, not because it was bad technology.) An acquaintance pointed out that I'd never get my prototype to the level of comfort and convenience that a modern gas powered automobile offered, even with a superior power plant.

        'tis a conundrum.

        Roger (too old to start cutting metal now -- I've a boat to build)
        derbyrm@...
        http://home.insightbb.com/~derbyrm

        ----- Original Message -----
        From: Bruce C. Dillahunty
        To: AtkinBoats@yahoogroups.com
        Sent: Friday, February 16, 2007 10:07 PM
        Subject: Re: [AtkinBoats] Re:electric drive for a tunnel stern?


        derbyrm wrote:
        > If you look at mpg figures for hybrid automobiles, it quickly becomes apparent that electric power is great for stop/go applications;
        I'll agree with that... I drive a Prius :-)
        > but not worth the effort for the sort of steady state effort that most boat propulsion systems are used in.
        >
        > Every time you convert from one form of energy to a different form, you lose a significant percentage to heating the atmosphere.
        > chemical => mechanical -- direct connection of gas engine to prop
        > vs
        > chemical => electrical => mechanical -- battery to motor to prop
        > vs
        > chemical => mechanical => electrical => mechanical -- driving electric motor with genset
        >
        I agree up to a point... there are a couple of mitigating factors though.

        1) You can operate the mechanical (gas/whatever) at its optimum
        efficiency instead of varying it to achieve other performance. This
        probably wouldn't outweight the inefficiencies, but would help offset
        them somewhat.

        2) You can use other energy sources (solar/wind/etc.) to supplement the
        gas... this is where the win is/is going to be in my opinion. I think in
        a few years we'll keep seeing solar drop in price and rise in
        effeciency. As I can get more power from the sun, I can rely on that gas
        engine less.

        Either way, its a neat technology :-)

        Bruce
        > Roger
        > derbyrm@...
        > http://home.insightbb.com/~derbyrm
        >
        >

        --
        Bruce Dillahunty
        bdillahu@...
        http://www.craftacraft.com





        [Non-text portions of this message have been removed]
      • donschultz8275
        ... batteries ... You could build a Jim Michalak AF4G. 22 flattie skiff with a slot type slot type tunnel at lease 6x1 in proportion ahead of the transom.
        Message 3 of 15 , Feb 17, 2007
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          --- In AtkinBoats@yahoogroups.com, "pkj49cello" <Johnst1@...> wrote:
          >
          > So what I think I need, is a 25 foot, easilly driven, room for two,
          > electric powered boat. I see using solar panels to power the
          batteries
          > for short hops, and a generator to help out for the longer runs.
          > Shallow draft would allow easy launches and access to distant creeks,
          > while a flat bottom would allow me to dry out should I want to really
          > explore. That is where the tunnel stern thought came from.
          >
          > I share Lewis's dream of silently cruising past all kinds of salty
          > wildlife- really I suppose, sailing without the sails.
          >
          > Any thoughts?
          >
          > Doug
          >

          You could build a Jim Michalak AF4G. 22' flattie skiff with a slot
          type slot type tunnel at lease 6x1 in proportion ahead of the
          transom. The motor well could hold the generator and gasoline, but
          I'd put the batteries amidship.

          http://www.duckworksbbs.com/plans/jim/af4/grande/index.htm

          Michalak's Twister is another possibility but is only a 16'
          motorsailor.

          http://www.duckworksbbs.com/plans/jim/twister/index.htm

          Checkout the simple tunnel design for this shallow water fishing
          boat. This is what I suggest could be added to the AF4G.

          http://www.bateau.com/proddetail.php?prod=XF20

          Click the link then click on the 'study plan' link. Part way down
          there is an excellent color drawing of the "tunnel"

          Don Schultz
        • Ken Grome
          Hi Doug, Canoes and kayaks are so slim that they slice very easily through the water. Some of them can run all day on trolling motors before their batteries
          Message 4 of 15 , Feb 17, 2007
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            Hi Doug,

            Canoes and kayaks are so slim that they slice very easily through the water.
            Some of them can run all day on trolling motors before their batteries give
            out. Maybe canoes or kayaks are what you really need for the type
            of "exploration boating" you've described ...

            Have you ever thought of using two boats? I like the ones shown in the links
            below . How about building two of them so each of you can have your own
            boat:

            http://www.jemwatercraft.com/proddetail.php?prod=Muskoka
            http://jemwatercraft.com/proddetail.php?prod=BucXW

            These boats can handle 800+ pounds of people and gear each, for a total
            capacity of more than 1600 pounds. That's a lot for two people! If it's too
            much capacity you could always build two of this model for a total capacity
            of 1000 pounds:

            http://jemwatercraft.com/proddetail.php?prod=Buccaneer

            You could put an electric trolling motor on any of these boats.

            If I were doing your exploring I might put a trolling motor on each boat, then
            bring along a very small (and quiet) 4-stroke outboard. Just put the
            outboard on the front boat and tow the other boat on your long treks.

            If you get an outboard with a charging circuit it would even recharge your
            batteries for you!

            Sincerely,
            Kenneth Grome
            Bagacay Boatworks
            www.bagacayboatworks.com






            > I spent three weeks in the ACE basin of coastal SC last spring. This
            > is an area of marshes and creeks between Savannah GA and Charleston
            > SC. It is mostly undeveloped, being protected by various Wildlife
            > Management areas. It has strong tidal currents, some stretches of open
            > water, but is mostly protected. The roughest conditions I encountered
            > were in Charleston harbour, shortly after launching.
            > The whole area is incredible for wildlife. One anchorage off the
            > Edisto river, I had (at different times) alligators and dolphins
            > swimming close to the boat.
            > I was on my 23 ft trailer sailor, but due to the narrow channels,
            > contrary winds and a boat (bless her heart), that doesn't tack worth a
            > hoot, we spent 100% of time listening to the two stroke.
            >
            > So what I think I need, is a 25 foot, easilly driven, room for two,
            > electric powered boat. I see using solar panels to power the batteries
            > for short hops, and a generator to help out for the longer runs.
            > Shallow draft would allow easy launches and access to distant creeks,
            > while a flat bottom would allow me to dry out should I want to really
            > explore. That is where the tunnel stern thought came from.
            >
            > I share Lewis's dream of silently cruising past all kinds of salty
            > wildlife- really I suppose, sailing without the sails.
            >
            > Any thoughts?
            >
            > Doug
          • Chris Partridge
            ... anything, as clean as you want to make it, full torque at zero rpm, quiet, and the Stanley Brothers built the best. (It failed for psychological and
            Message 5 of 15 , Feb 18, 2007
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              >>>I once spent several hobby years designing a modern steam car. Burns
              anything, as clean as you want to make it, full torque at zero rpm, quiet,
              and the Stanley Brothers built the best. (It failed for psychological and
              marketing reasons, not because it was bad technology.) An acquaintance
              pointed out that I'd never get my prototype to the level of comfort and
              convenience that a modern gas powered automobile offered, even with a
              superior power plant.





              The advantages you list, especially full torque at zero rpm, are just what
              you need in a boat. How about designing a marine version?

              Chris



              [Non-text portions of this message have been removed]
            • derbyrm
              Actually, the marine application is quite different; little starting and stopping, relatively limited environmental temperature changes, greater need for
              Message 6 of 15 , Feb 18, 2007
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                Actually, the marine application is quite different; little starting and stopping, relatively limited environmental temperature changes, greater need for economy. Marine steam plants used quite exotic arrangements in the name of efficiency; compounding, feedwater heaters, economizers, ...

                Everything I know about Stanley Steamers came from a wonderful little book: "The Story of a Stanley Steamer" by George Woodbury. He restored a 1917(?) model from terribly decrepit condition but was able to talk to original owners and mechanics.

                Some gems I remember:

                One of his initial test drives after years of restoration found him cruising down a country road. He glanced down at the speedometer and discovered he was doing seventy miles an hour on the forty year old wooden spoked wheels. He slowed gently but immediately. (A Stanley built steamer held the world's speed record for a long time -- 114 mph on the sands of Daytona Beach with really primitive suspension.)

                His neighbors had a tennis court near his garage. One evening he came back from a ride, noticed the neighbor's wife about to serve, and, without thinking, tripped the boiler blow down valve. The serve went into the next county. (Railroad locomotives had mufflers on their blowdown valves to keep the neighbors happy.)

                His wife took the car to town one afternoon. Fires in the boiler compartment were not significant and went out promptly, but someone had called the fire department. If they were allowed to dowse it, she would be stuck for an hour or so while she got pressure back up, so she fled town, streaming fire and smoke, and pursued by the fire truck with sirens and bell.

                As I said, I'm too old to start cutting metal and ideas that look great on paper often turn out differently in practice.

                Roger
                derbyrm@...
                http://home.insightbb.com/~derbyrm

                ----- Original Message -----
                From: Chris Partridge
                To: AtkinBoats@yahoogroups.com
                Sent: Sunday, February 18, 2007 9:19 AM
                Subject: RE: [AtkinBoats] Re:electric drive for a tunnel stern?




                >>>I once spent several hobby years designing a modern steam car. Burns anything, as clean as you want to make it, full torque at zero rpm, quiet, and the Stanley Brothers built the best. (It failed for psychological and marketing reasons, not because it was bad technology.) An acquaintance pointed out that I'd never get my prototype to the level of comfort and convenience that a modern gas powered automobile offered, even with a superior power plant.

                The advantages you list, especially full torque at zero rpm, are just what you need in a boat. How about designing a marine version?

                Chris
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