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Thread: Diesel/Electric drive?

  1. #36
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    Default Re: Diesel/Electric drive?

    A customer of mine has been developing a hybrid system for a couple years now. As of right now it is still cost prohibitive for most, but that hasnt deterred him from continuing research and development.


  2. #37
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    Default Re: Diesel/Electric drive?

    Quote Originally Posted by jjgrayston View Post
    Key takeaway, if you’re considering a conversion purely for the sake of fuel efficiency then you are likely better off sticking with a conventional diesel engine as any efficiency gains probably won’t be enough justify the additional cost.
    Key takeaway I was getting is that variable pitch props are probably a good idea, combined with instrumentation that lets you take advantage of them.
    2019: returning from being sidelined with medical probs, crossing fingers worst is over, still in "armchair enthusiast" mode for time being.

  3. #38
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    Default

    And how about diesel/hydraulic? Hydraulic drive motors are pretty cheap these days. Put the motor anywhere you like. No alignment problems. Isolate the motor in a nice quiet box somewhere. Run a hydraulic anchor winch, and even a sail handling winch with a bunch of rope clutches. Sheet winches. You could incorporate an electric hydraulic motor in the mix to trim sails without running the motor.

    Sent from my CPH1851 using Tapatalk

  4. #39
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    Default Re: Diesel/Electric drive?

    Quote Originally Posted by Phil Y View Post
    And how about diesel/hydraulic? Hydraulic drive motors are pretty cheap these days. Put the motor anywhere you like. No alignment problems. Isolate the motor in a nice quiet box somewhere. Run a hydraulic anchor winch, and even a sail handling winch with a bunch of rope clutches. Sheet winches. You could incorporate an electric hydraulic motor in the mix to trim sails without running the motor.

    Sent from my CPH1851 using Tapatalk
    I think the efficiency losses are quite large with hydraulic motors.
    If you cant make it accurate, make it adjustable.

  5. #40
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    Default Re: Diesel/Electric drive?

    I think it's the same as electric genny/motor efficiency, you can get it but you have to pay a lot for it.

    If you can get enough solar to loaf along at 4 knots on solar alone there is more point. Kinda suspicious of some solar hybrid systems that claim speeds like that, but the numbers don't seem to quite add up and one suspects they are drawing down battery. I think you'd need slender multihulls to support the likely expanse of required panels between them.

    Otherwise the points made earlier apply, it works for cars because of huge speed/efficiency mismatches, it shouldn't work for boats where you're in any way sensible about picking your prop, motor and cruising speeds.... unless you can make a case for spending 33% or more of your time moving around marinas. The numbers may work better on UK or Euro canal networks.

    As I understand it for propellers in freewheel mode, which have been measured to slow a boat down more than locking the shaft, it's unlikely that meaningful regeneration is possible. For low speed boats, paddle wheels might look better.
    2019: returning from being sidelined with medical probs, crossing fingers worst is over, still in "armchair enthusiast" mode for time being.

  6. #41
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    Default Re: Diesel/Electric drive?

    I don't envision loafing along at 4 knots indefinitely on solar power. I envision a sufficient battery bank that I can collect solar, wind and hydro while under sail such that I have a few hours worth of power to get me into or out of a harbour. A large slow heavy cruising boat that speed isn't the top priority can comfortably carry the battery bank required for this. And as it essentially replaces the diesel tanks, it means your stability doesn't change when under power. Over the course of a voyage, the fresh water consumed will improve her stability as her tanks will be in the deck house just above the water line.
    If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
    -Henry David Thoreau-

  7. #42
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    Default Re: Diesel/Electric drive?

    The curse of solar with sail in North America and Europe, is that westerlies are the prevailing winds, so if you have solar flat on the decks, and sail, you're gonna be heeled away from the sun most of the day on average, apart from early morning. Thus insolation of your panels throughout the day is gonna end up being a third or so of what you were counting on. I reckon you'd want a lot of say up to 1ft wide panels on a monorail wrapping around the gunwhales (Hanging like curtains almost) so you can move them to windward side of boat which will likely be at a good angle to sun most of the day.
    2019: returning from being sidelined with medical probs, crossing fingers worst is over, still in "armchair enthusiast" mode for time being.

  8. #43
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    Default Re: Diesel/Electric drive?

    Regarding using the prop as a turbine to produce regeneration under sail:

    Note that the camber of propeller blades is concave at the rear, and convex at the front. Turbine blades need to be oppositely cambered. If you had some sort of pod that you could spin 180 degrees, or a reversible pitch prop, that still doesn't solve the problem, as the sharp propeller trailing edge becomes the leading edge of the turbine blade, while the more rounded leading edge of the prop becomes the trailing edge of the turbine. This will result in poor efficiency at best, and more likely cavitation and rapid wear. Nearly all boats have this issue when reversing, but that is only used when coming to/from dock, or setting an anchor, so isn't a huge issue.

    So if you wanted to back-drive the motor as a generator, you'd probably need some way to switch the prop out for a turbine. It might could work with a reversible pitch prop IF you could make the blades reverse pitch by going through the feathered position (infinite pitch) , rather than through zero pitch.

    Honestly, I'm an electrical engineer, a fan of green power, and electric cars. Marine requirements (steady, known load, hours, even days of continuous operation at optimal efficiency power after warm-up) are nearly an ideal use case for a diesel internal combustion engine. The ideal use case for a regenerative hybrid electric drive is short duration, variable loads.
    Last edited by Kevbo; 07-22-2019 at 08:47 AM.

  9. #44
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    Default Re: Diesel/Electric drive?

    Second kevbo, for regen to work you need a dedicated spinner with completely different Shape and much finer pitch than a drive prop. Then you need to be consistently running over 7 knots which means probably a yacht at 40' or longer.
    I would love to go electric for seeking up creeks but is still need 24-48 hrs of run time for passage runs if I'm motor sailing.
    As a day sailer doing 1-4 hrs running then back to a marina berth to charge up each night then I think it has a place.
    The cost for the diesel electric battery system is still too much $ and weight for me.
    Nanni and Beta both do a combo diesel electric.
    Z

  10. #45
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    Default Re: Diesel/Electric drive?

    Came across this design the other day, https://www.duckworks.com/product-p/bk-eco62h-id.htm I think that one has serious potential for a solar-electric build. I'm getting a spitball of 1200-1400W you could cram on that roof area. I think one might lighten up the roof structure a tad, it looks like it's designed to walk on, so you'd have to forgo that and put the solar up there, ensuring enough strength for the spread panel weight of course, but since walkability would suggest it supports 200lb/sqft ish then the thickness of it could be minimised, though cabin sides and roof crosspieces may end up carrying same. Then if it's not too tippy yet, get maybe another 400W in several independent panels on a wrap around "curtain" rail, you can move to the sunny side. 6 golf cart batts low down and I think you could cruise a day on those, and be plenty of buffer for cloudy spells and generous "house" use. Probably need to keep everything else super light in order not to weigh it down too too much. Anyhoo, anyone with about $10,000 and a couple of years spare could have a crack at it
    2019: returning from being sidelined with medical probs, crossing fingers worst is over, still in "armchair enthusiast" mode for time being.

  11. #46
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    Default Re: Diesel/Electric drive?

    I heard designer Bob Stephens give a talk last night about diesel/electric drives such as in this design of his: https://stephenswaring.com/yachts/zogo/

    He said that the power used was most efficient at about 4.5 knots, but the drain doubled at 7 knots and doubled yet again at 9.

  12. #47
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    Default Re: Diesel/Electric drive?

    I looked somewhat seriously at electric motor for my boat when i was doing a repower. I went for a diesel in the end because of the kind of sailing i do.

    Reading blogs and such by people who use electric power it seems that it suits those who are full time cruising or out for extended periods. If you have no time constraints it works. You sail everywhere, regardless of light airs, and only use the motor for the 15 or 20 minutes you need to pull up to a jetty or mooring. Solar will bring the batteries up to charge just fine over the few days/weeks between uses.

    For me, mostly day sailing and weekend sailing with family - time is an factor. I have to be back at the mooring Sunday evening before it is dark, to get the kids home for school and me home for work the next day. If i want to get to where i am going and enjoy being there, and then back to the mooring against a strong wind, I have to be able to get the boat up to speed and keep it there for a couple of hours.

    Having said that i am rarely in that position and really only need a motor to get me on and off my mooring....

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  13. #48

    Default Re: Diesel/Electric drive?

    I have been vaguely thinking about changing out an inboard Yanmar GM10 to a rudder mounted electric motor on our Folkboat. But:

    1) Solar Panels - well these are not exactly long lasting in a marine environment, and unless you pay a lot of money the crystaline structure seems to start to break down after three or four seasons. Given that they are mostly plastic cased - not exactly good for the environment

    2) Lead Acid, or Lithium batteries - again expensive and end of life - again an issue.

    3) A simple diesel engine is very long lived. In the club are several yachts with engines that must be 40 plus years old. They potter along sipping fuel. Even Mr Katonka, as our 1 GM10is called is 12 years old and still in first flush of youth. And end of life easy to recycle.

    4) OK they use diesel fuel which is a hydrocarbon. Diesels can run very well on vegetable based oils, although the challenge is stopping bugs growing in the fuel tank.

    5) Best solution is called Sails and swinging moorings - you can hoist sails and sail on and off quite easily. Sails are a very echo friendly form of propusion. Have an easily driven hull (ie not a modern seagull poo* made white contraption) and it will be fast in light airs, and when the wind drops break out the oars or sculls.

    *Did n't you know that GRP boats are made by filling a mold with fibre mat and then let seagulls poo all over it!

  14. #49
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    Default Re: Diesel/Electric drive?

    Pushing back a bit on the conventional wisdom on display in this thread, here's a nice discussion of the pros and cons of electric propulsion by a young couple who are actually out there cruising - with no diesel at all! The upshot seems to be that as long as you treat it as a true auxiliary and aren't trying to stick to a land-based schedule, it's a viable option with quite a few advantages. It's certainly something I'm considering for Astraea.


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