Electric outboard drive for small cruisers

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  • 10 Mar 2020 18:04
    Reply # 8819438 on 8809939

    David,

    have you estimated for how long you can drive the motor with 2-3 kts speed with your battery choice?

  • 10 Mar 2020 11:48
    Reply # 8817617 on 8809943
    Annie wrote:

    I should love to trade the BBB for electric, but dare I ask what it all cost?  And please could you give me the dimensions of the ginormous solar panel?

    As Fanshi should be able to carry more weight, I would go for something more like these: good deep cycle AGM 130Ah batteries at £390 and 62kg for a pair. Sadly, I don't think Weaverbird and I could cope with batteries as heavy as that.
  • 09 Mar 2020 09:26
    Reply # 8809969 on 8809939

    Sounds almost excactly like the plan I’ve had in mind in case some kind of surpirise funding would suddenly appear. The Haswing has changed the situation a lot more appealing.

  • 09 Mar 2020 09:23
    Reply # 8809952 on 8809939

    The Haswing motor - £587

    The Relion batteries - £1600

    The 360W panel - £300 and it measures 195cm x 99cm

    The solar panel controller - £85

    The step down converter - £9.35

    The shoreside charger - £85

    Last modified: 09 Mar 2020 10:13 | Anonymous member
  • 09 Mar 2020 09:07
    Reply # 8809943 on 8809939

    I should love to trade the BBB for electric, but dare I ask what it all cost?  And please could you give me the dimensions of the ginormous solar panel?

  • 09 Mar 2020 08:56
    Message # 8809939

    Jim's electric drive project for Hobbit got me thinking. I'd investigated electric drive before, when I was looking for sensible auxiliary drive for Weaverbird, but couldn't see how to work it out, so bought a Tohatsu 6HP Saildrive.

    Things have moved on a bit now. It still makes absolutely no financial sense, but it does now make practical sense. As I have said before, I will never be a petrolhead, and I will always dislike having to have an infernal combustion engine aboard. Add to that the fact that the outboard well does not accept a large 4 stroke outboard very well, needing it to be left in place in the water all summer, and something had to be done. Weaverbird and I could not accept the weight of the Tohatsu on a transom-mounted bracket, and I thought that I would have difficulty starting it in that position, but an electric outboard is half the weight, and starting it is non-existent issue.

    So I've started on an electrification project. 

    I have bought a parallelogram outboard bracket and mounted it on the transom. I am currently making up a removable plug for the outboard well, so that water doesn't splash up it and into the cockpit at speed (another annoyance I'll be glad to get rid of).

    I have bought a Haswing Protruar 5HP 24v electric outboard. This weighs 14kg, half the weight of the Tohatsu. The Haswing is the thing that has become available recently to make the project reasonably sensible. It is claimed to be equivalent to a 6HP petrol outboard in thrust, but I rarely need that much. I need half an hour of full throttle motoring on rare occasions (strong tides on the UK west coast, mainly), but mostly, trickling along at 2 - 3 knots will be enough, using much less power. It's good to have the extra power in reserve, just for the occasional burst when necessary, and I will feel comfortable with using it so long as I can then wait a day to recharge.

    I have bought a pair of Relion 100Ah lithium batteries to be wired in series. This is the expensive part of the project, but all the available electric outboards with integral batteries use lithium - it's the only way to get enough energy stored within an acceptable total weight. The Haswing and the Relion batteries weigh 40kg together. Using any form of 120Ah lead acid battery would make the total weight 76kg, with less usable stored energy, and I really don't feel able to lift 31kg batteries aboard and into place. The Tohatsu with a full tank of fuel also weighs 40kg. I have a sliding tray under the cockpit that has held six 10litre water containers, but I will sacrifice two of these to put the Relion batteries in the best place - low down, and as near to the motor as possible without having to make a watertight battery box to mount outside over the old outboard well.

    I have bought a 360W rigid solar panel - the largest that I can squeeze onto the deck between the mast and the companionway. When I added up what I would have to do to mount a lighter semi-flexible 350W solar panel, there wasn't much saving in weight, there was a lot of fabrication to do, and  the rigid panel cost a lot less. The panel will extend over the forehatch, but the hatch can still be cracked open for ventilation. I've not used it to get in and out of, so I don't think this will be a problem.

    I have bought a high efficiency 20A MPPT solar charge controller, to wring every last available watt out of the panel.

    I have bought a 24v to 12v step down converter, to run the existing 12v systems off the 24v battery.

    I have bought a high-spec battery charger for those occasions when I go into town for stores, and shoreside power is available.

    There will be some other sundries to add, but those are the major components.

    Last modified: 17 Apr 2020 07:29 | Anonymous member
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