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Discussion in 'Boat Design' started by abh, Jan 19, 2012.

  1. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    yeah, much much slower. And all they run on it is their nav system and lights.

    You were talking about driving a motor. Those things you found in the google search make 200 amp hours per day at best. - and that is with fast sailing, downwind. read their blurb.


    Lets see - 200 amp hours by 12 volts = 16 watts
    Thats .002 HP. Now, how do you run a motor with that ??

    Then lets consider the batteries to store enough to drive a motor.

    see
    http://www.boatdesign.net/forums/hybrid/battery-thread-some-facts-please-41978.html

    and find out why you couldn't store enough power on this size boat even if you could generate it.

    Remember, every battery on a boat reduces is sailing speed too.
     
  2. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

  3. dskira

    dskira Previous Member

    Yanmar had a very nice one cylinder 9hp. They are not anymore available in the US unfortunately. It was here a best seller. Never broke, always ready, and sipping fuel like a Lady a Martini.
    Thank you EPA for spoiling our days of efficient and (relatively) cheap motorization.
     
  4. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    Funny how you talk without knowing what you talk about. When you want to comment on an article, the least you should do, beside thinking, is to actually read it.

    Because it's pretty obvious you did not read, the rest of your post cannot be taken seriously.
     
  5. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    Do not make generalities out of a specific case. The link you post is clearly for racing boats, and optimized for them.

    When you look at the size of the propeller in comparison to the size of the boat, it should be pretty obvious that such a system cannot be compared to the power generated by a propeller able to move the boat at 15+ K under full power....

    You know, this whole discussion make me think that, if Internet forums had been in existence when Thomas Edison invented the light bulb, it would have never happened! It was obviously ridiculously complex and costly in regards to the existing technologies of the time to get light, candles and oil lamps. Listening to all the great advices read here, he should have stuck to cheaper, simpler, well proved technologies. You know what, I am glad he did not!

    regards,
    Bernard
     
  6. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    Again, maybe you should learn how to read.

    First, your reasoning does not make much sense, at all. I agree that any weight on a boat reduce its sailing speed. So maybe the first thing to do would be to remove the keel, right?

    May I remind you that we are talking about a specific boat, here, where 180 Kgs of batteries are part of the ballast, so saying that batteries reduce boat speed is ridiculous, as without batteries it may be much faster, but not go very far.

    Now, go on to your calculations: "200 amps hour par day" is a meaningless sentence. As 200 Ah on a day makes for 4800 A, which at 12 v is 57.6kW

    What you mean is 200 Amps per day, which might be true for small inefficient systems.

    Now, if you look at this http://www.shop.solar-wind.co.uk/acatalog/Water_turbine_LVM_AQUA4GEN_Manual.pdf
    which is what I call a small inefficient system, it gives, with the larger blades, 4 Amps at 5 K for 12 V, or 48 watts. Assuming a day at 5 K average speed, this means 1152 watts produced, or 96 amps to store.

    To run the engine, we need 6 * 100A batteries. Assuming we never go below 50% discharge, we need 300 amps to fully load them back. With +- 20% loss in between the wires, charger, etc, it would take +- 4 days to have them fully loaded, without using solar panel and/or windmill. With a couple of 40W solar panels, that would be done in +- 2 days.

    Where is the impossibility here?
     
  7. dskira

    dskira Previous Member

    BernardG don't take over the thread.
    These members have a lot of experience.
    Do you sail a lot with the system you pretend to be the best?
    Why everyone who disagree with you doesn't know what they are talking about?
    I ask because what I read from you is just prose from the internet.
     
  8. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    Experience, what kind of experience? on this forum, sure!

    They don't know what they talk about because they have decided, once and for all, that an extremely experienced sailor, designer and naval architect was totally wrong in creating a sailboat with an electric engine as secondary propulsion engine.

    Allow me to have quite strong doubts about their electric experience/knowledge when they are constantly confusing between Amps and Ah, for example.
    Even you, here, in those questions, are very biased; Where do I say that using an electric engine as power generator is "the best" ??? Please, quote me. What I do say is that, when calculating the power available to generate electricity on a sailboat equipped with an electric engine, this very electric engine MUST be taken into account. Which none of the "very experienced" forum members did.

    To get back to a previous message, when Thomas Edison invented the light bulb, he had absolutely no experience with it, either.

    best regards,
    Bernard
     
  9. dskira

    dskira Previous Member

    You didn't answer my question, you still just going around.
    The question was: Do you sail a lot with the system you pretend to be the best?
    About your judgment on the members, you should avoid hasty comment like the one you made.
    As for your Edison statement, now you really looks dumb.
    Are you compeering yourself to Edison?.
    I knew French has the best wine in the world, doesn't mean you have to abuse of it.
     
  10. dskira

    dskira Previous Member

    Is that not pretending your method is accurate, and proved by you since you trumpet it? And you go on and on about it if we disagree?.
    Are you changing your mind ? You'r sending mix message. Not good.
    Do you sail?
     
  11. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    You probably could build a boat with enough stored energy and charging capacity . the problem is 25 ft. its too small for solar, too small for batteries, too small.............
     
  12. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    Why would I have to answer your question? First, I never "pretended" that what I talk about is the "best" system. Try to quote me on this. There is no such thing as a "best system", it simply does not exists, as a sailboat, like many other things, is a matter of compromises between so many different parameters, just like there is no "best sailboat".

    BTW, if I must make an explanation of text, I never compared myself to Edison. What I stated was that, before making it work, Edison had no experience with light bulbs, which should be obvious to anyone having at least a little common sense. Meaning that, when you are doing something you have never done before, you have to trust something else than experience, which Edison did, and which is what I am doing too.

    Best regards,
    Bernard
     
  13. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    Yes, and?

    Bernard
     
  14. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    Sure, you must be right, because you say so.
    They are way too small to cross the Atlantic too, right ?

    Bernard
     

  15. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Dont put words in my mouth. Ive been across the Atlantic 2 dozen times with sailing yachts.

    Outline your energy budget please.
     
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