Diesel/Electric Propulsion for Sailboats

Discussion in 'Hybrid' started by westsail42, Nov 3, 2005.

  1. westsail42
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    westsail42 Junior Member

    Ok,

    So I just read the short article in the latest Ocean Navigator on Diesel/Electric Propulsion in pleasurecraft.

    I have also been looking at the Whisperprop site http://www.whisperprop.de/eng.

    My science/engineering background tells me this makes so much more sense than traditional diesel propulsion.

    Of course, most old salts would say avoid this like the plague. Diesel propulsion is tried and true (but there are even saltier salts that would say avoid an auxilary altogether). There are always going to be armchair quarterback nay-sayers. I read that most cruise ships built in the last 10 years are D/E (usually a Z-Drive type).

    What say you?
    Is this really coming to pleasurecraft?
    How developed is this technology?
    What will the next 5 to 10 years bring?
    Are there other players in this market?
     
  2. D'ARTOIS
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    D'ARTOIS Senior Member

    First of all, Diesel-Electric propulsion is widely used in military and large commercial craft. There, it is no exclusion but rather common sense. When we look at the advantages for small craft, then we will see that there are a limited number of conditions that such an investment is paying off.

    I think that you should come forward with your motivation why such an expensive system would be better than the conventional shaftdrive one.

    Please make us happy and explain.
     
  3. westsail42
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    westsail42 Junior Member

    Wel, DID NOT say it would be BETTER. I wouldnt dare use such a highly subjective term to ASSERT anything (which I am not in this thread).

    I said it seemed to make more sense, because of power efficiency, easier installation, quieter, smoother power delivery.

    Oh yeah, note I did not metion COST. Of course cost is probably the single factor in success determination. Which accounts for the questions regarding the future of this technology at the bottom of my original post (which maybe you did not read).
     
  4. D'ARTOIS
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    D'ARTOIS Senior Member

    Croix moi, I have nothing against diesel-electric : on the contrary! But exactly on a small craft it does not make sense. Not only because of costing but also for available space and weight.
    You should be really more specific rather than drop this interesting item in the bucket without proper background and justification.
     
  5. cyclops
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    cyclops Senior Member

    Hold on there. He stated his depth early on. Take a strain. All hail Caesar!
     
  6. cyclops
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    cyclops Senior Member

    On small, under 40 ', the weight and waterproofing of the electronics is really a disaster due to saltwater burning up the drives and leaving you with no main drive. These drives require a on board electrican / mechanic to maintain.
     
  7. D'ARTOIS
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    D'ARTOIS Senior Member

    Cyclops, if I was too sharp, I apologise Westsail 42, it is not my intention to spoil a discussion.
     
  8. cyclops
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    cyclops Senior Member

    Oh yes, reprograming of the complete drive may become necessary at the height of electrical storms. :)
     
  9. westsail42
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    westsail42 Junior Member

    Yeah, I imagine one would have to become more of an electrician rather than a diesel mechanic to maintain. And certainly, trying D/E in a small boat NOW would be crazy.

    But, the purpose of my original post was to start a discussion on wether this technology has a FUTURE in pleasure craft. Of course time would be required to work out the kinks.

    One wonders, with the advancement of technology, cost of oil, general movement towards more "green" technology,
    if and when this technology will be ready for prime time, if ever?

    As we have seen the adoption of technologies from OTHER markets (pleasure boats, at one time, NEVER had radar, GPS, gensets, etc. But now it is very common), will we eventually see this too?

    just wondering...
     
  10. caribmon
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    caribmon Junior Member

    Electric Drives - Propulsion of the Future

    by Richard Kastelein

    In my opinion, electric powered boats have definite advantages. They are environmentally friendly, and very quiet; they run with only a whisper of sound. They are reef friendly, quiet in harbours, are cheaper to run and emit no pollutants.

    So why are we still using fossil fuels and Marine diesel engines to provide propulsion for ocean going vessels?

    Consider the typical internal-combustion engine. From the time a charge of fuel ignites in a cylinder, it has to push pistons, turn a crankshaft, turn a camshaft, open valves, pump water, pump oil, turn an alternator, and submit to reduction from a transmission to step the engine's thousands of revolutions down to something a propeller can use. By the time that's done, the engine's efficiency is somewhere below 25 percent. Also, diesel engines are rated at their maximum rpm - and on sailboats are rarely operated at that speed.

    [​IMG]

    By contrast the the efficiency of Solomon Technologies' electric motor is a percentage in the low 90s. Here's how it works: When the system is switched on, DC current from the batteries enters an electronic controller, which produces expanding and contracting magnetic fields in the motor's stator windings. These magnetic fields attract and repel the fields from three permanent magnets, made from neo-dymium iron boron, that are attached to the rotor.

    The controller electronically modulates the pulse width to increase or decrease speed. At 13 inches wide, the motor provides ample contact with the shaft to produce high torque at low rpm, enough for the motor to turn particularly large propellers. Fixed three-bladed 18/18 (diameter/pitch, in inches) propellers are typical in many of STI's installations. From the flowing electrons to the turning prop, the shaft passes through only two bearings and a stern gland - and no transmission, all of which accounts for its high efficiency. Furthermore, with the electric motor, the relationship between rpm and torque is linear: You can use it to turn the boat's prop at 1 rpm or 10 rpm or 50 rpm or 100 rpm. An internal-combustion engine needs to cross an rpm threshold before its propeller is put in gear; otherwise, it would stall.

    [​IMG]

    Probably the most amazing aspect of the STI's electric drive is its ability to produce electricity with a low-speed, high-output alternator driven by the prop shaft when a boat is under sails. In other words, the device is converting the prop's rotation into stored energy.

    [​IMG]

    [​IMG]

    Other new developments in this area of Electric drives are being addressed with companies such as ASMO Marine and Fischer-Panda for utilising electric propulsion in production craft as well as Fast Electric Systems and MW Line in Switzerland for using straight electric drives in larger vessels.

    For those that prefer a little more muscle in terms of power - and would prefer to have a dual propulsion system - the hybrid diesel-electric may be the answer. Whilst it's more environmentally friendly - straight electric is not practical for some commercial operators, powercats and motorsailors for a variety of reasons including availability of shorepower, horsepower issues, or lack of a backup system.

    For those who prefer a dual system there's a couple of options.

    One is using DC generator input for electric drives. What's the difference in fueling up a DC generator with diesel to top up batteries in order to directly drive a propulsion system ... and just using a normal diesel engine? Lots.

    There is a huge amount of savings in terms of fuel consumption as well as a much quieter generator as opposed to a chugging diesel. The emission differences are also significant. The downside is the size and weight of the battery banks needed and more money initially invested (which is eventually recouped through fuel savings). The DC Whispergen is powered by a Stirling engine that needs no oil, is almost completely silent... it operates unobtrusively with a noise level similar to a domestic air-conditioner.

    Lightweight, compact and efficient, the WhisperGen converts over 90% of the fuel supplied into heat and electricity.

    Then there's the Vetus option - where electric propulsion is integrated into the diesel engine much like the hybrid cars one sees on the road today. The general idea is to use the diesel engine when you want the power and switch to electric propulsion when you want some peace and quiet. When motoring under diesel power, the electric motor, driven by the diesel engine, functions as a dynamo, charging the batteries for the next round of electric propulsion. It's a nifty system.

    [​IMG]

    This technology is more than viable... the US military is planning to shift over a significant proportion of their vehicles to hybrid technology in the future. The Humvee will be replaced by the more efficient Shadow RST-V - which is the US Marine Corps' first 4x4 hybrid-electric tactical vehicle.

    Richard Kastelein
    Avante Yachts LTDA
     
  11. brian eiland
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    brian eiland Senior Member

  12. caribmon
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    caribmon Junior Member

  13. cyclops
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    cyclops Senior Member

    What is the complete cost and eff. of any electric powered boat when you add in the pollution and cost of burning fuel at a powerplant to generate electricity, transmission losses and repairs, cleaning the plants gases. Most people do not add in the battery companies costs and pollution either. Each time energy is converted it loses some eff. Do a oil in ground to prop turning eff. study and anything electric loses out. Electric power is a very wastefull form of power. And I like electrics.
     
  14. brian eiland
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    brian eiland Senior Member

    I think you would do well to read these two PDF's http://boatdesign.net/forums/showpost.php?p=61065&postcount=5 This DC technology in generation and usage promises a lot less in losses than you traditionally think of. And the 'battery' storage capacity does not have to be that great as the generator source may only need to be run at just the level required by the motors unlike AC systems in general.
     

  15. cyclops
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    cyclops Senior Member

    Actually I went to the company web sites and read their statements . I came away with a MG system that weighed twice as much as a standard home MG. Regulating the voltage or frequency by controlling the engine speed, is caveman engineering. Very slow response compared to electronic. Does not lend itself to UPS. Uninterrupted Power Supply or Service. The present day control of multiple power sources mandates very high speed switching speeds in all parts of a complete system. -----------They are selling a 1920's DC power system back to us. Plus, they want you to buy special dc voltage common appliances, to get a sole source strangle hold on you. Wait for a part or the hole appliance? When low 120/240 vac are cost effective. You can pay for the overpriced system that is so oddball, a company tech is flown out to your boat.
     
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