Charging Up to Hybrid

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  • 15 Dec 2019 16:18
    Reply # 8286220 on 8266733
    Anonymous wrote:

    And how about an Amazing new electric boat motor based on fish fins!

    Having looked at that page there are a few things that come to mind. The first (already mentioned in the comments) is how long does that membrane last? how much does it cost in money, complexity and time to change it or even inspect it?

    The next thought is that one of the problems with IC engines that most electric motors don't have is reciprocating parts that aside from being noisy, tend to wear much quicker as well as being less efficient.

    The last thought is about stream speed. The outlet of this motor is very small. Anyone following the history of jet engines might have noticed, a large diameter slower moving stream is much more efficient than a small diameter high speed stream. Outboards with "high thrust" propellers on them are larger diameter, low pitch to move more water at a lower speed. This leads to some question of their claim: "The FinX is 20 to 30% more efficient than propellers." (note they said "than propellers" so how the prop is driven is not relevant) Their output jet is maybe two inches in diameter or less compared to 10inches or more from a prop. There is not even  shroud around the outlet to help change speed to volume using the venturi effect.

    Of course the size of the unit and drag thereof compared to the resulting stream is another question.

    So at first glance, this is a concept that (like hydrojets) is best used for high speed craft... if it can get the craft up to high speed in the first place. Call me skeptical but certainly I am wait and see on that one. (I note they have not yet actually used this unit to push a boat... or it has been such a flop they don't want to publish the video) Their web page is somewhat deceptive too, there was one link to "data sheet" that magically turned into a "preorder now" button when you click it (so you have to remove the item from your shopping cart)... and of course the picture of a boat planing at high speed is not using their motor as they have no motor rated for such use at all.


  • 15 Dec 2019 12:49
    Reply # 8284807 on 8266733

    And how about an Amazing new electric boat motor based on fish fins!

    The FinX motor looks very promising. It's not based just on theory but established practice in industrial and medical settings.  Simpler still than electric motors. It looks very easy to maintain. And they're claiming 20 - 30% greater efficiency than propellers. 

    Imitating the action of fish-fins. Biomicary is the future!

    I remember the US Navy was doing experimental work imitating tuna fins. Called: Tuna drive. And then came work at MIT on penguin fins. Called: Penguin drive. That website suddenly disappeared. Maybe they discovered something they didn't want to share.

    Hobie Cat offers a man-powered "flipper-drive" for their personal watercraft. AKA, "Mirage Drive." But I digress...





  • 15 Dec 2019 12:11
    Reply # 8284566 on 8265784
    Anonymous wrote:

    Jim,
    now I have re-read your initial posting of this thread, and I am about to turn more positive to you conversion project.

    Your plans have changed from long-distance to local or coastal cruising. The matter of battery range is therefore not so important, and with that Honda generator in cold st.by, hidden in the cockpit locker, the battery bank needs not be that big (2-5 kWh?).
    I checked the Honda  EU2200i generator. It can even be made to run synchronously with a second Honda, if you later find you could use more power.
    The lovely thing with this Honda is that, besides being good, it is light enough (21kg) to bring ashore for service, repair or replacing it. Much cheaper than if you get trouble with a diesel.

    With this setup, there is less need to complicate things by turning your ship it into a complete solar plant. After all, you have a car. If you let your Honda generator burn up to 10% of what the car burns in a year, you could well end up with 100-200NM range based on the Honda power alone. I suggest you keep it simple for the first summer. That will soon show you your needs.

    However, the greenest way of propulsion is sailing. Therefore I stress the need for keeping the rig sorted out so hoisting sail doesn’t possess a big obstacle. I also keep saying that cambered junk-sails are the greenest of all, since they let you move upwind both effortlessly and fast enough.

    I apologise if my earlier postings have sounded discouraging, and I wish you good luck!

    Arne

    PS: Just for the record; what is the ‘burst’ power of the electric engine?

    PPS: That lovely young couple on Youtube surely was resourceful and not shy of doing some hard work! Being on the wrong side of 60, I prefer to cut corners and rather lower my ambitions. I am not quite the Houdini that I used to be...



    Hi Arne, Thanks for your comments and support. I appreciate it. Apology accepted.

    The eyes of the JRA and my boat club are upon me, so I'd better produce and keep folks informed. It's a bit complicated, comparing apples and oranges. For the time being, I need to point to experts to answer some of the questions that arise. I'll be better informed as time passes.

    Yes, I'd best keep things simple in the first season. 

    The electric motor, applied to sailboats is in the early stages of development. At this point, one hears, "Oh that's nice but the range is too short." It's like the saying, "Junk rigs are fine except they don't go well to weather." How long will it be before that assumption is put to rest by your cambered sail? I think your cambered sail concept is the most important development of the junk rig in generations, made possible, of course by modern, stable fabrics. You made a huge investment of time, thought and labour into its development. You can be proud. But I know you don't want to rest on your laurels. I know, we wish we were on the other side of 60 with the owners of Uma. 

    I was a Houdini in my youth. I'm fortunate to have a large engine space on Hobbit. (A Benford 30' Sailing Dory) As engine spaces go, it's amazing. However, I've had to teach myself the choreography of careful twists and turns to get in and out without stress.

    How will the range question be answered? To have better batteries is our first thought. Meanwhile, the owners of SV Uma have answered that question for themselves. When they navigated the Intracoastal Waterway, sailing, and motoring, they managed their range deficit by study, planning, timing, and patience. (Of course, they don't have to adhere to a tight schedule.) There is a word for that: seamanship. Good seamanship. Who would know? That's all our ancestors had. They are "voyaging on a small (energy) income," to borrow a phrase. :-)

    Of course, there will still be many places you can't go because power is a necessity to overcome extreme situations. There are still lots of great places to go to!

    BTW, there is an adapter available to convert a Honda EU2200i from gasoline to propane or natural gas. So you have a choice of one of three fuels at any one time.

    "All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident." -- Arthur Schopenhauer




  • 13 Dec 2019 23:26
    Reply # 8270429 on 8265784
    Anonymous wrote:


    PS: Just for the record; what is the ‘burst’ power of the electric engine?


    "Burst power" (in HP) does not make a lot of sense with an electric motor in the way it might with an IC. They do have momentary torque which is pretty much equivalent. In theory, an electric motor has maximum torque at 0RPM which then falls away with speed such that a constant HP is kept to maximum speed. In reality, The maximum torque is set by the maximum current the windings can handle without burning up which is controlled by a mixture of winding size and cooling available (the same motor may be rated twice as high with water cooling instead of air cooling). As a result most electric motors have a large portion of their speed range where current and therefore torque are constant (normally about half the speed range). In the case of the project in question, the motor is expected to spend it's life within this constant torque range.

    In this case, the continuous current draw is rated at 125 Amps. The motor can stand 420 amps for up to 60 seconds.

    I am sure there are some bright minds who are going "great, 1 HP is the same as 750-ish watts and we know the voltage so we can convert to HP". Actually no. The equation for HP can be set by using torque and speed or mass over distance. So if the motor torque is 15 Nm but the rpm is 0 then HP is 0 as well. So if the motor is constant torque till 3000rpm then the only time it makes sense to equate electrical power to hp is at 3000rpm. Of course torque in the case of turning a prop from idle to starting to turn is more important... try starting your IC motor with the transmission engaged (and the prop in the water of course). Many cargo ships use electric motors as the transmission for this reason (most trains too). In general, IC engines are poorly matched to low speed, high torque loads while electric motors do very well for this use.

    But wait! there's more... The unit in question on the quiet torque web site lists the motor's maximum torque as 35Nm which does not match up with either the continuous current rating (15Nm) or the max for  60 seconds rating (50Nm). What gives? Well, at 35Nm the motor should be able to run for more than 60 seconds, so maybe a bit of fudge factor to save the motor... I don't think so. These maximums are rated in Amps and so far we have only talked about the motor itself. There is another component involved which also has limits. The controller.

    The controller takes DC current in and converts it to three phase (for this motor) at the frequency that matches the motors rpm (or a multiple thereof). Motor controllers do this with pass elements which even run in full on (minimum resistance) still have some voltage drop which means they dissipate heat. So the maximum current they can pass is also based on their ability to stay cool enough to not burn up. In this case, the controller limits the amount of current maximum to 290Amps. So burst power electrically, is 13920watts at 48v and continuous is 6000watts at 48v. So burst power is about 200% with whatever method you use for calculating that.

    Of note: While the electric motor is able to produce maximum torque at 0 rpm, in a boat this does not happen for very long because as soon as the prop starts to turn torque goes down too. Everything changes faster than it can be calculated at any one speed.

    I have tried using some of the prop calculators on the web to see what size/pitch prop would make sense for an electric motor. They don't work very well because they assume 0 torque at 0 rpm. The actual prop calculation is done with torque not HP but they calculate torque from HP and assume a torque curve from an IC engine... which is wrong. The prop as calculated this way has a lower size and pitch in order to be usable at low rpms (without stalling the engine) where an IC engine has little torque. (while the electric has full torque)

    Probably way more than you wanted to know... sorry.

    Last modified: 13 Dec 2019 23:31 | Anonymous member
  • 13 Dec 2019 16:48
    Reply # 8266733 on 8133077

    For anyone interested in looking into electric drive, there's a useful site at:

    https://plugboats.com/

    Of particular interest to me, with a boat that doesn't suit outboard motors very well, be they petrol or electric, there's a comprehensive guide to pod motors.

    And how about an Amazing new electric boat motor based on fish fins!

  • 13 Dec 2019 14:49
    Reply # 8265784 on 8133077
    Anonymous member (Administrator)

    Jim,
    now I have re-read your initial posting of this thread, and I am about to turn more positive to you conversion project.

    Your plans have changed from long-distance to local or coastal cruising. The matter of battery range is therefore not so important, and with that Honda generator in cold st.by, hidden in the cockpit locker, the battery bank needs not be that big (2-5 kWh?).
    I checked the Honda  EU2200i generator. It can even be made to run synchronously with a second Honda, if you later find you could use more power.
    The lovely thing with this Honda is that, besides being good, it is light enough (21kg) to bring ashore for service, repair or replacing it. Much cheaper than if you get trouble with a diesel.

    With this setup, there is less need to complicate things by turning your ship it into a complete solar plant. After all, you have a car. If you let your Honda generator burn up to 10% of what the car burns in a year, you could well end up with 100-200NM range based on the Honda power alone. I suggest you keep it simple for the first summer. That will soon show you your needs.

    However, the greenest way of propulsion is sailing. Therefore I stress the need for keeping the rig sorted out so hoisting sail doesn’t possess a big obstacle. I also keep saying that cambered junk-sails are the greenest of all, since they let you move upwind both effortlessly and fast enough.

    I apologise if my earlier postings have sounded discouraging, and I wish you good luck!

    Arne

    PS: Just for the record; what is the ‘burst’ power of the electric engine?

    PPS: That lovely young couple on Youtube surely was resourceful and not shy of doing some hard work! Being on the wrong side of 60, I prefer to cut corners and rather lower my ambitions. I am not quite the Houdini that I used to be...


    Last modified: 13 Dec 2019 16:39 | Anonymous member (Administrator)
  • 13 Dec 2019 12:45
    Reply # 8264856 on 8264358
    Check out the video series (I linked to the first video, I think there are three in total) and/or read here: https://www.sailinguma.com/electro-beke

    This is an excellent link. I strongly suggest reading this page before posting declarative statements based on hasty assumptions.  It will answer many of your questions, better than I. 

    Concerning the philosophy behind the author's choice to go to electric, I like their "mission statement":

    We have found that having a solid plan and the patience to wait for the right weather and tide is the key. - After all, we own a sailboat. They are inherently slow. We are not in a rush. We love the idea of being self-sufficient. But, for those who sail with schedules, are short on time, lack the patience to sit out a wind hole, feel the need to power their boat to hull speed, enjoy maintaining a diesel engine or are just set in their ways, then an electric motor probably isn’t the right choice


  • 13 Dec 2019 11:29
    Reply # 8264358 on 8133077

    Yeah that's indeed an interesting project. I don't remember the story completely but they bought an identical engine (used) to replace the broken one that came with the boat but for some reason it didn't work out so they went electric instead. They bought a a used electric motor from a forklift for practically no money and then setup everything together themselves, with a bunch of trial and error.

    Check out the video series (I linked to the first video, I think there are three in total) and/or read here: https://www.sailinguma.com/electro-beke

  • 13 Dec 2019 03:13
    Reply # 8260912 on 8260735

    Did you maybe mean Uma and Sailing Uma?

    https://www.youtube.com/watch?v=_L1xmG5Kndw

    Thanks for the correction.
  • 13 Dec 2019 02:49
    Reply # 8260735 on 8249322
    Anonymous wrote:
    I think you summed up the reason for the difference in prices very well. I'm not knowledgeable enough in electrical matters to presume I could assemble a system by myself, like the owner of Suma. See the blog, "Sailing Suma"

    Did you maybe mean Uma and Sailing Uma?

    https://www.youtube.com/watch?v=_L1xmG5Kndw

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