10m LOA Electric Powered Trimaran for Flatwater

Discussion in 'Boat Design' started by Alias_Go, Aug 3, 2021.

  1. Alias_Go
    Joined: Aug 2021
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    Alias_Go New Member

    I'm new to the forum, though long time reader. I've built a wooden ski boat previously as well as other composites projects.

    I have recently become interested in designing and building a trimaran as a hobby project.

    The scope is that I would like a quiet long range efficient boat for weekend/week long use on flat water and i think battery+ solar technology is now good enough to do what i want. But with range and efficiency in mind i'm liking the challenge of a Trimaran.

    I saw the Shuttleworth Trimaran "Adastra" before COVID hit and thought that would be an ok starting point inspiration wise.

    If I take the Adastra dimensions and quarter them, i get to dimensions that feels bout right for what i want, i.e. 10m LOA, 4m Beam.

    Looking a bit deeper to get the Length to beam on the central hull of 17, would give a 10m equivalent a beam of 0.6m and to get a similar Length to displacement ratio would give a 520-700kg displacement overall.

    Ignoring practicality for a moment. Do you think a vessel in this size range with similar philosophy of Length to beam and displacement to length is possible to achieve?
     
  2. gonzo
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    gonzo Senior Member

    You should look at most typical trimaran. The overall beam you propose is extremely narrow. You will have to use exotic fibers, sophisticated engineering and very skilled labor to get the overall displacement at twice what you propose.. A four person crew with minimum supplies for a weekend will weigh about 400 Kg which leave almost nothing for the boat.
     
  3. Alias_Go
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    Alias_Go New Member

  4. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    AG, I think that the Small Trimarans site should be an excellent reference resource for you.

    But you should try to define your Statement of Requirements (SOR) a bit more.

    It is all very well having a trimaran with a very skinny and super efficient main hull, but it is not much use if you have no cargo capacity whatsoever as mentioned by Gonzo (although he mentioned it the other way around).

    If you go for a cruise on this trimaran for a weekend (or even a week) - how many people will be on board?
    How much water will you have to carry with you? What about stores / provisions?
    Or can you re-fill with water and buy food at every place you go to?
    It all adds up very quickly.
    What speed do you ideally want to achieve?
    And assuming full batteries, what range do you need to have at that speed, assuming no top-up from the solar panels?
    Everything in boat design is a compromise - there is never a 'perfect' solution.
     
  5. kerosene
    Joined: Jul 2006
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    kerosene Senior Member

    Just seconding what others have. Scaling boats doesn’t work too well - you are better of defining your needs/wishes.
    How many people, what amenities, what speed range - with solar EV it’s displacement speeds or just a tad more with very skinny hulls.

    Imo camp cruiser (or even small cuddy) solar powered cruiser is entirely realistic. Check the currently active thread with a solar boat:
    "Current Situation" DIY Efficient Solar/Electric Powered Newport 17 Project https://www.boatdesign.net/threads/current-situation-diy-efficient-solar-electric-powered-newport-17-project.64961/

    With purpose built setup and long waterline you can expect fair bit better performance. Panels get large and quite heavy so placement of them is something that needs some attention. 450 watt panels are 24kg / 50lb, so not horrible. 4 of those is 1800W and on average 4-5 peak hours per day you could get 7.2-8kWh per day. Probably lower range of that as panels wouldn’t be angled to sun. Then again average includes bad weather days so if you are out mostly when its nice numbers would be better.

    desired speed and range dictate the power and battery. If 1kW slow cruise is enough a 4kWh LFP battery could be enough. 4h is a decent buffer for the dark or hurry.

    keep sharing your ideas.
     
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  6. BlueBell
    Joined: May 2017
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    BlueBell "Whatever..."

    "Ignoring practicality for a moment. Do you think a vessel in this size range with similar philosophy of Length to beam and displacement to length is possible to achieve?"

    Yes, but it's a very strange question.
    What does that mean, "...possible to achieve..."

    Your "undisclosed" location makes it impossible to know seasonal daily average solar availability.

    Only your SOR will tell you if the design meets your needs or not.

    Not enough information mate!
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    The whole specification here is poorly outlined, what is "long range" ? That seems to imply the Tom Cruise "need for speed", if just a weekend, but maybe you idea of long range is different to mine, without a clear specification of the task, it is not a productive discussion for you. List your range and speed and weight carrying requirements, and you will have a good starting point, in working out the feasibility.
     
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  8. gonzo
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    gonzo Senior Member

    In general "long range" means ocean crossings. It would be good for the OP to state what distance he requires.
     
  9. HJS
    Joined: Nov 2008
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    HJS Member

    In 2007, we built this 7.5 meter long trimaran with electric drive. The purpose was to get a basis for being able to calculate larger trimarans. The diagram shows the power requirement at different total weights.
    The values can be transformed into larger boats.
    JS
     

    Attached Files:

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  10. alan craig
    Joined: Jul 2012
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    alan craig Senior Member

    Title states "...for flat water" so not ocean crossing.
     
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  11. gonzo
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    gonzo Senior Member

    @ Alan: Maybe, one can never discount wishful thinking.
    @HJS: the graph shows that at higher speeds the power consumption is very sensitive to weight. Very interesting data.
     
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