Electric auxiliary to Antarctica

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  • 11 Oct 2021 22:41
    Reply # 11345732 on 10752801
    Anonymous member (Administrator)


    as you may remember from our ‘memorable’ sail-trip in Ingeborg, her engine too was a Tohatsu 6 Sail Pro, with extra long leg. Since 2018 I have run it on the very clean Alkylate petrol which keeps the plug clean even if I never reach to warm up the engine properly before hoisting sail. Total consumption this summer, after 15 outings, appears to be two litres.

    Frankly, I think the bracket on that Norlin was a normal bracket, but I had a bracket on rails on my Malena (standard on Albin Viggen), and I have seen other motors running up and down on rails. They appeared to be custom made from 25mm tubes.

    You should have good access to the transom from the inside of the aft cabin, to let you beef it up a little with a stout piece of plywood.

    I think your electric inboard will shine as a harbour manoeuvring motor. I can also think of it as very helpful in a tight spot when sailing. You will always have a ten-second burst of power at hand in case the boat refuses to come about. Invites to braver sailing....


    PS: A possible extra advantage with the outboard is that it will be much quieter when hidden behind the transom and with the aft cabin between you. Remember, sound level drops with 6dB each time the distance is doubled.

    Last modified: 11 Oct 2021 22:44 | Anonymous member (Administrator)
  • 11 Oct 2021 21:04
    Reply # 11340836 on 10752801

    Graeme - I think the propeller is 16" with a pitch of 15" but could not swear to it without going back through emails.  It is definitely two bladed and not folding or feathering, Arne.  I wonder if the two bladed aspect explains the cycling of the regen, as the prop is close behind the keel.  The reduction is 2:1. I am not sure about efficiency and do not have the monitoring equipment or expertise (or time and interest, if I am honest) to measure accurately, but I did a ton of research and calculations when I was setting up the system three years ago and 8amps (400W) for 2.5 knots is close enough to my expectations that I guess it must be acceptably efficient.

    Horst - I have not even (hangs head in shame) connected the battery temperature sensor yet, never mind thinking about a sensor for the motor.  For the light usage I am giving it, the motor has never felt more than slightly warm to the touch, but I have not yet had it running for more than an hour or so at low draw. I think your solution sounds good - I had also considered a sail drive solution, but decided to stick with the shaft drive that was already there.  I tried to get a Kiwi prop on Finn - the Norwegian Gumtree - but sadly missed it! From what I have read, they are a good choice for an electric setup, though it may take an extra lift out or two to get set up correctly.

    Arne - I shouldn’t admit this, but I had not even considered using an outboard instead of a generator - it is a good idea.  The Tohatsu 6 Sail Pro that I had on the IW 31 was surprisingly capable as an auxiliary.  Once you add a generator into the system and have a fossil fuel aboard anyway, there is no reason not to consider an outboard and as an added bonus the outboard is out of the way - the generator takes a fair chunk of floor space in the aft cabin. You don’t happen to know where they got the rails from on that Norlin, do you? Although I can picture how it may look, I do not remember seeing anything like that when browsing the online chandleries.

    I also agree with your comment about gung-ho sailors and I would generally include myself in that group - I am much less likely to reach for the start button than many of the people I sail with.  I had underestimated how different that is when family sailing, though.  Although the boys enjoy sailing and are keen to come along, we generally have a target in mind when we go out together and they are less accepting of light winds, low speeds and flexible destinations than I am. I certainly do not want to dent their enthusiasm, as I am hoping they will be crewing for me (or I for them) into my old age!

  • 11 Oct 2021 19:09
    Reply # 11334713 on 11320036
    Anonymous wrote:

    I will go with a 10kW water-cooled motor from Golden Motor on a Yanmar Saildrive. Also the controller is prepared to be water-cooled. It is a little effort (time- and money-wise) to build such a small fresh water cooling system and it also would be nicer to avoid the water but I want the system working also in really hot conditions.


    That is a very nice and neat install, well done.

    I follow electric propulsion because I think it is the way of the future but for myself, gas is it... 2 stroke if that is what the budget will carry. It will be a long while before used electric parts of any quality at good prices will make this a reality for my use. (I expect as much as 20years away)

  • 11 Oct 2021 14:22
    Reply # 11320036 on 10752801

    Thank you for sharing your experience here Mark!

    I'm also in process of changing the propulsion to electric. Even though a good part of the needed hardware is on board already it still will take me a long time to finish the project.

    I will go with a 10kW water-cooled motor from Golden Motor on a Yanmar Saildrive. Also the controller is prepared to be water-cooled. It is a little effort (time- and money-wise) to build such a small fresh water cooling system and it also would be nicer to avoid the water but I want the system working also in really hot conditions.

    Do you measure the motor temperature? What are your readings at maximum in summertime?

    I bought Winston batteries from Hong Kong and paid 190USD for a TSWB-LYP160AHA. The price includes delivery and all costs arising because of the import to EU in my case. Perfect service and communication with the shop in Hong Kong but the packing could have been better.

    I'm planning to use my old Kiwi prop with 16" diameter and an adjustable pitch between 18 and 24°. The reduction of the Yanmar saildrive is 2.64:1. I also could use a 17" Kiwi prop which I found in the garbage bin recently (!)..


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  • 11 Oct 2021 09:50
    Reply # 11306573 on 10752801

    Thankyou Mark for a frank and very informative appraisal of your electric installation.

    I found it very interesting to compare your experience (and conclusions) with Kurt (Mehitbel) with whom I have recently been corresponding – he too uses the Thunderstruck 10kw inboard engine kitset on his 12m x 12 tonne vessel. I think he is turning a 18" propeller and the reduction here is 3:1

    I am guessing you will have swapped notes with Kurt too.

    Out of curiosity, what is your propeller diameter, (and pitch if possible) and what reduction are you using with the electric motor?

    Last modified: 11 Oct 2021 09:53 | Anonymous member
  • 10 Oct 2021 22:24
    Reply # 11286576 on 10752801
    Anonymous member (Administrator)

    Keep it simple; add an outboard engine...

    Frankly, I don’t think it is a good idea to replace an internal combustion engine with a 100% electric installation on a small boat. Small boats are inefficient in terms of kWh per ton-mile, much unlike bigger ships. A small boat needs a power of 2-4hp/ton while a 10000ton ship is very happy with 10000hp. The exception may be the British narrow-boats, meant for the low speed on the English canals.

    Changing to electric propulsion for a motor boat will only...

    • ·         .. turn a big fortune into a much smaller one, in particular if sufficient solar panels are to be fitted to keep one independent of shore power.
    • ·         ..delay the project and keep one high and dry for a good while...
    • ·         ..give one range neurosis...

    Pure electric power is only useful as aux. power on a sailboat if the sailor and his/her crew are gung-ho sailors who sail in most conditions and only use the engine in and out of crowded marinas.

    I think a hybrid solution is better. If Mark’s boat were mine, and in its present state, I would use it as it is, but then add a 4-stroke  6 or 9.9hp outboard on the stern, reserved for extending the range on those days with no wind. The stern of the Maxi 95 can easily take an outboard which goes up and down on a pair of rails. I have seen a Norlin 34 (similar transom) with an outboard like that: The diesel had just gone on strike right before vacation, so the dinghy’s Honda was pressed into service. That worked very well. Access to the outboard on a Maxi 95 may not be good, but it is only meant to extend the range, not for harbour manoeuvres. The powerful electric engine, with the controls at the wheel, is better for that.
    By running the fuel through an outboard, one makes better use of it than when running it through a petrol generator+inverter+charger+electric engine.
    Edit: In addition, the propeller of the outboard does not drag in the water when not in use. Does the inboard engine have a feathering propeller?

    This solution is much quicker to fit, Mark, and it lets you spend the winter doing better things than acting a boat electrician. I am sure you can find a useful second-hand ob. unit on FINN.NO.

    Good luck!

    Last modified: 11 Oct 2021 11:01 | Anonymous member (Administrator)
  • 10 Oct 2021 20:56
    Reply # 11283770 on 10752801

    I finally got my Maxi 95 on the water this year after what has felt like half my life doing the rebuild, conversion to JR and electric drive.  She has not had much use - it was already July before I got the rig set up and ready to go, but I can comment a little on the electric drive for this thread, after about ten day sails.

    For background, the boat has a 10KW sailboat kit from Thunderstruck.  The battery pack is 4x100AH AGM batteries, over ten years old, but I did not want to buy new batteries until I had tested everything else.  The boat is kept in a marina with 220v power and I use a Victron charger/inverter (20amps) for charging. Solar is among this winter's projects, but that is OK, as I have only been day sailing as I get to know the boat this year.

    In summary, the system works as it should.  I have plenty of power for manoeuvring a five ton boat around the marina or in and out of rocky island tying-up spots. It is blissfully quiet, and there is no smell of diesel aboard, nor do I have to face the challenges of servicing a diesel engine without double jointed arms and elbows.

    However, range anxiety - even for day-sailing - is a very real phenomenon. If I just use the motor for going in and out of the marina on a light-wind day sail, I can use as little as five percent of its capacity, which is fine. If we motor a bit further into more spacious water, or the wind is stronger, it is usually ten percent.  If, as my children like, we then sail to one if Norway's hundreds of islands and stop to explore, that is doubled, or more than doubled if we have to do a bit of circling and trying different spots.  Things are improving as I get to know the system. Low speeds certainly helps and at 2.5 knots in light winds, I am only pulling 8 amps at 48v, giving me a theoretical range of 12nm to 50% DoD, or about 7nm if you take out the 20% used at the marina and lunch stop.  Replacing the battery pack will solve some of my anxiety here, of course, but to get up to a semi-decent range will be very expensive.  At 20 amps in light winds and flat seas, we make about 4 knots, which is a more reasonable speed but, even with a lithium bank at 5KW hours (100AH ish) that will only give 12-15nm range with a bit in reserve for the mooring etc.  I would rather have double that so that I am able to take longer weekend trips next year and know that I will be able to get home in time for work!  I own a 1600W inverter generator from Kipor and the idea was that this would be a power supply for light wind sailing.  Unfortunately, I have not been able to persuade the Victron charger to recognise an input from the generator so far.  Apparently, this is a known problem with the Victron Multiplus system.  There is a work around, which I will be trying when I get some spare time. 

    The battery pack is the big expense.  In an ideal world, I would have a 12-14kwh pack, made for the boat from LifePO4 cells.  At Norwegian prices, this would come in close to 25000 euros.  I could make it myself from Alibaba cells for about half the price (as Arne mentioned somewhere, 48v is the limit for DIY in Norway), but I am honestly not comfortable putting together such a potential firebomb without professional help. I can use 12 or 24v batteries in series (some of them - not all - have a BMS set up for series use) but they need to have a big BMS that will take the 200 amp draw at full throttle.  Here in Norway, the cost of that is a bit more palatable at around 8000 Euro for a 10kwh (4x200ah).  There are other options, but these are the best two so far.  The cheapest, around here, would be to buy an 8kwh pack made with used car cells at around 2500Euros.  But I would have to lie about the purpose of the purchase as the CE approval specifically says that used car packs shall not be used on boats due to increased fire risks. The local guy who makes them fitted packs into boats before the rules changed, but I sail with my children, so cannot really live with taking that risk.

    The regen feature on the Thunderstruck setup starts to work at about 5.5 knots, but it only cycles in and out - I have never seen a constant input into the battery pack.  To all intents and purposes, I am fairly sure it does not add any more juice into the batteries than the amount of power taken by having the ignition switched to on when sailing.

    As Graeme mentioned, though, motorsailing in light airs is a definite winner.  The Maxi has poor steerage at very low speeds, particularly if there is a slop, and on a recent trip when the wind dropped, adding three amps of power kept the speed high enough to keep us moving in the right direction, and prevented a family mutiny from down below, where the chess pieces were falling off the board.  This was in winds that were well below five knots.  I am fortunate that the Maxi sails well, even in lighter winds.  I think an electric drive would be a poor choice for a more staid and steady boat.

    Overall, I am happy with the system in most ways, but the cost of putting a decent battery pack and solar system is going to be similar (even with the cheaper option) to the price of a brand new diesel engine.  So while I am happy with the motor, love the quiet and the flexibility of it, I am not, in all honesty, sure I would make the same choice again, particularly for family sailing around the islands in Norway.

  • 26 Sep 2021 21:26
    Reply # 11122361 on 10752801

    Nils wrote: I can't easliy see the connection between electric motors and Junk Rigs...

    It doesn't suit everyone, of course, but in this article in the JRA archives, the writer describes quite a nice relationship between junk rig and electric motors.

    (I should add, I realise I have been a bit selfish in cluttering the forum with these recent threads on electric motors. It really has been (and is) beneficial to me to learn from other JRA members who know a lot more about these things. I thought maybe there would be some other people interested, and I had assumed anyone not interested would just skip these threads. I hope it has not been too tiresome and if it has, I do apologise.)

    Last modified: 27 Sep 2021 03:17 | Anonymous member
  • 26 Sep 2021 20:54
    Reply # 11122320 on 10752801

    Electric propulsion is an interesting topic in itself, but I can't easliy see the connection between electric motors and Junk Rigs.  Have I missed something important here?

    Best regards


  • 23 Sep 2021 00:37
    Reply # 11111629 on 11107133
    Anonymous wrote:

    My experience with motors suggests that DC is  significantly more efficient than AC.  It has a maintenance issue however with brushes and commentators that wear out over time.    AC operates via induction instead of brushes and commentators and offers long term virtually maintenance free operation.........BUT it requires that DC be inverted to AC and transformed to the optimal voltage..... or the voltage must be produced by series and parallel topology of the battery pack.   3 phase AC has the wonderful feature of being variable speed simply by varying the frequency...... if the motor is designed to accommodate it.

    Umm, I think that all motors require AC or switched current. That switching is done either by electronics or brushes. This is the first time I have heard of "DC" motors being more efficient. Though you do mention "AC" motors use induction so perhaps you mean AC induction motors as opposed to AC motors in general, though there have been advances in induction motors as well. Most AC motors used for motive power are permanent magnet AC motors which are at the heart of pretty much all the brushless "DC" motors out there (including the $1 specials in your computer). A DC brushless motor is an AC motor with an electronic switch or controller.

        All of this calls for some fairly complex costly electronics, some components of which is failure prone... such as electrolytic capacitors.   Most DC motor systems vary speed by electronics also.... using pulse width modulation, though DC voltage could be varied using series parallel connections to change speeds, limiting the sensitive electronics.

    PWM controllers are no less pron to failure as any other motor controller... less so than brushes though. Electrolytic Caps come in various grades and can last a long time if good grades are chosen. Most AC motor controllers that offer speed changes and power control are PWM controllers as well. They do not put out a sinwave but rather pulse width modulated square (for some definition of square) pulses that provide a sine wave of power to the load. Varying DC voltage either requires complex switching (probably electronic like PWM) or series resistance which wastes power (by the time the series resistance equals the load impedance, one quarter power, efficiency is less than 50%). It would be possible to tap power off of only part of the battery but that would mean uneven charge and discharge.

     I would assume cars that use AC motors use much different frequency than 60 cycle.

    Continuously variable dependent on speed (the same as brush motors). Most do not use induction motors though but rather permanent magnet motors with the magnets on the rotor. In some cases the rotor is outside of the field for greater torque but most of the 10-20kw units used on boats have the field outside.

      I personally own a couple of pieces of equipment that operate at around 10,000 cycle, and vary the frequency depending on the circumstances to regulate output.  The transformers are tiny, compared to what would be required at 60 cycle, and generate a fraction of the heat.

    400hz used to be common for portable equipment that needed greater than battery voltage, mostly transievers with valves in them. 40k to 48k is pretty common these days though as it and it's most annoying side bands are outside hearing range. I think 10k would give me a head ache :)  But yes for a motor controller that is in the ball park.

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