Solar Trimaran concept - please review.

Discussion in 'Boat Design' started by kerosene, Oct 22, 2020.

  1. kerosene
    Joined: Jul 2006
    Posts: 1,062
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    Location: finland

    kerosene Senior Member

    El-tri-Imperial.jpg El-tri-Metric.jpg

    a 20ft'ish pylwood tri. Narrow waterline but wider "upper hull".
    2ft beam waterline, 7" draft. 1/4" plywood with 6oz glass (+ more on seams), deck and floors 3/8" ply
    Akas and reinforcing wood local pine.
    2 more bulkheads under front and rear decks.
    Straight hull section in cockpit area for modularity.

    600w Solar + 24V 100Ah LiFePO4 (100% cycle ok) + about 1000w (draw) 24V brushless trolling motor (2-3 options that are cheap in that range).

    Goals for design:
    -easy to make
    -family camp cruising on nearby lakes
    -30 nm range @ 5 knots
    -typical summer day solar would cover range requirements
     
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  2. kerosene
    Joined: Jul 2006
    Posts: 1,062
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    Location: finland

    kerosene Senior Member

    Resistance per freeship looks like this.
    To convert power requirement to electrical draw I multiplied by 2. Not sure if that is still too optimistic.

    cheers



    upload_2020-10-22_15-51-4.png
    upload_2020-10-22_15-53-6.png
     
  3. kerosene
    Joined: Jul 2006
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    Location: finland

    kerosene Senior Member

    I used 50% efficiency assumption from electricity draw to propulsion. Seems that William Fraser had that kind of efficiency on his very purpose built solar kayak setup so I doubt it is a realistic level for trolling motor, even with better prop.
     
  4. kerosene
    Joined: Jul 2006
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    Location: finland

    kerosene Senior Member

    I guess it is perfect then...
    :)
     
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  5. Clarkey
    Joined: Aug 2010
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    Location: UK

    Clarkey Senior Member

    Well it certainly seems quite reasonable. Even if you find that you can't reach your targets at 5 knots it looks like a small speed reduction will bring the range within reach. I guess it will hinge on motor and prop selection but you knew that already.

    We must be pretty close to a solar electric setup competing favourably with a decent sailing rig on cost grounds now?
     
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