electric or multifuel engines?

Discussion in 'Boat Design' started by longliner45, Feb 9, 2006.

  1. longliner45
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    longliner45 Senior Member

    Im considering electric power because of supply of fuels.but what about multifuel engines? can I put enough electric power on a boat that weighs 11000 lbs to get 4 or 5 hrs cruising time ?or is it better to go with diesle or something else. If im offshore and a storm comes Ill surly have wind. but if im off shore and no wind ill need to get back some how?
     
  2. Sander Rave
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    Sander Rave Senior Member

    It's a long story. but to cut a long story short:
    Getting home with little or no wind won't be a problem. Getting home on your motor upwind will be.
    If you stay below 80% of full throttle you can go on cruising for hours if you calculated it to work for little time full throttle.
    I think you need to get your priorities straight. Without them it's impossible to make a good choise. Maybe a hybride is an option?
    To get the same performance you will gain some weight.
    This is the short and bold version.
     
  3. FAST FRED
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    FAST FRED Senior Member

    The traditional solution is a SAIL.

    No thousands of pounds of batterys that take days to recharge, no diesel stench , no gas fire hazard.

    Very GREEN,

    FAST FRED
     
  4. Sander Rave
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    Sander Rave Senior Member

    The bank of (semi-traction) batteries shouldn't be discharged too much to safe life time. If you do so, Charging time will not be so much problem. On the other hand, you have to keep them under tricklecharge current if your moored.
     
  5. longliner45
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    longliner45 Senior Member

    this would be my reserve or should I say secondary ,this will be for 32ft sailboat just to get out of the slip .
     
  6. kach22i
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    kach22i Architect

    Double post.
     
  7. kach22i
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    kach22i Architect

    If you run out of power, you will just have to jump on one of these.

    http://www.gadgetizer.com/2005/10/19/ocean-scooter-fx-inflatable-electronic-jet-ski/
    [​IMG]

    Just kidding............I could not find a lot of good stuff to post on this topic. Seems to be a budding industry though.
     
  8. safewalrus
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    safewalrus Ancient Marriner

    that electrickery is OK but it's the length of lead that worries me! :rolleyes:

    But seriously I am under the impression that whilst good for steady consistant running electric tends to be slow!! From my experience, whilst limited (diesel electric dive support vessel) she ran like a dream but sudden requirements to alter power levels (like sudden bursts of speed to get outa the brown stuff) were a big NoNo! :p 'Lotsa' diesel submarines ran submerged on batteries for years but were somewhat slow! (Just as well it made it easier to catch 'em):p
     
  9. BillyDoc
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    BillyDoc Senior Member

    Walrus,

    That was true of the older technologies. Now, you can design your vessel with a much larger motor, that motor can be a brushless DC type with LOTS of torque, and you can control the power output from almost nothing to full out by a bit of trickery called "Pulse Width Modulation" without sacrificing (very much) energy in your control system. PWM is made possible by high current switching transistors that can be turned on and off very rapidly. The motor itself is basically a big coil of wire, so it has a lot of a property called inductance. Inductance, like capacitance, can store energy. So, if you hit such a motor with a few brief pulses spaced over time the inductance in the motor will integrate these pulses and give you the equivalent amount of power out. Widen the pulses and you get more power. The advantage of this approach is that the transistors are either full on or full off, so they are not subjected to much of a voltage drop when actually passing current. That makes the whole system efficient, whether drawing full power or just a little.

    Electric motors can give full torque at zero RPM, so a very efficient propeller can be used with them as well. It's one of the reasons Diesel electric trains are so common and work so well. No transmission required is nice too.

    Did that make sense? There will be a 20 question test next Tuesday.

    Bill
     
  10. safewalrus
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    safewalrus Ancient Marriner

    Bill I bow to your greater knowledge - it still looks like electrickery to me, so being an old fart, I'll be taking it with a pinch of salt!

    I think I understand what you are saying but it will need some more research on my behalf before I'll believe it (that's bullsh** for I'll have to read it again 'cos at the moment it's going way over my head! there again I'm the only guy I know who can change a light bulb and blow the whole system such that it takes an real electrishun a week [four days actually] to fix it)! :eek:

    Electrics just ain't my thing!
     
  11. BillyDoc
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    BillyDoc Senior Member

    Actually Walrus, it's magic!

    Don't worry about it though, I've been playing with this stuff since I was eight years old (and I'm 62 now) so I probably skipped over a lot of the important stuff and made it impossible to understand. I'm definitely going to be using electric drives on my next boat though. Diesel generator, two electric motors. No transmission, lots of torque, maneuverable in port . . . and if you do it right you can use the motors to re-charge the batteries when you have extra wind. It seems I often have LOTS of extra wind. And for a guy who loves to sail . . . I HATE WIND! In excess, of course. A nice 10 knot breeze is alright . . . right pleasant, actually.

    Nothing's perfect.

    Bill
     
  12. longliner45
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    longliner45 Senior Member

    could I have electric drive with small onan generator? how much will it cost? remember , one small 32 ft sailboat,
     
  13. JPC
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    JPC Junior Member

    As much as we all cringe at the thought of heavy electrics in the water environment, what I have read supports BillyDocs comments: as long as everything is sorted out well, you get a much more versatile propulsion source using electric motors on certain-sized vessels.

    But, IMHO, the size of vessel you're talking about is below the sweet spot (it seems that, to do it well requires some significant engineering space/weight), and even the sweet spot is going to cost a premium.

    You can Google some electic drive units; they're pretty pricey.

    In your opening post you mentioned supply of fuels. What is the problem you're trying to overcome?
     
  14. longliner45
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    longliner45 Senior Member

    cost and availabilty of fuels I see another fuel crisis coming, some day they will ration diesle for only comercial use. ......so my thinking was solar electric or a multi fuel engine , I have seen them in military vehicals, also seeing bio diesles Im not rich but I want to make my investment last, I plan on using the boat untill it kills me ,,,,longliner
     

  15. trouty

    trouty Guest

    Longliner

    This guy - of your vintage seemed to have it worked out!

    http://www.rexresearch.com/hubbard/hubbard.htm

    [​IMG]

    I mean - at the website - there is a photo & a diagram - how hard can it be?

    Looks just like coils within a big coil to me!

    I know people hate it when I speak / post of Motionless electromagnetic Generators, but peolpe take a look around you - just how long can we stay addicted to oil?

    Someone explain to me how Hubbard cheated on this "test" in front of the assembled press?

    Anyone?

    Cheers!
     
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