need help in building a small catamaran

Discussion in 'Multihulls' started by yoram, Nov 18, 2010.

  1. yoram
    Joined: Nov 2010
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    yoram Senior Member

    I would like to build a small cat. About 4-5 meter long, for 2-3 people with some comfortable way of sitting on it. I want it to sail in calm fjord waters, no real waves beside every now and then a ferry wake. I would like to build it from friendly material like plywood or fiberglass or both. The boat would go by electric motor and 3-4 marine type batteries. No sails, so it would go slow, no planning. I want it to have relatively flat or round shape on the bottom of the ama (I think this is the term for the 2 pontoon like on the sides of the catamaran but do correct me if I am wrong) so I could drag it on the beach. I have a monohull sail boat with which I can not access all kind of shallow nice beaches and I would like to have this boat to do so. Flat bottom is easier to build then round, at least the way I see it. My priority is that it would be easy and simple to built, light, good hydrodynamics shape but could be compromise to a degree for the benefit of easy building, cheap to build, no fancy accessories on it.
    What would you recommend me to do? Size-proportion between length and width, the shape and size of the ama,, the shape and size of the board that connects the amas etc.
    I would really appreciate any idea, comment, etc.
    Thanks
     
  2. DarthCluin
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    DarthCluin Senior Member

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  3. yoram
    Joined: Nov 2010
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    yoram Senior Member

    thanks. i wish i would know the measurements of this boat

    how much is its wight, where to locate the batteries, should i place the outboard electric motor at the back or should i make some kind of hole in the floor in the center of the connecting board to place the motor? (it is a light wight electric motor), where to place the the connecting board in relation to the two pontoons, is it practical to have it only 4-5 meter (13-16 feet) long and how wide should it be in this length etc.
    anyone with some kind of ideas?
     
  4. sabahcat
    Joined: Dec 2008
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    sabahcat Senior Member

    Thanks for the link
    I liked the link from that page to skeeter
    I want one and will seriously consider this as a dinghy for my current build
    [​IMG]
     
  5. spidennis
    Joined: Feb 2007
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    spidennis Chief Sawdust Sweeper

    Reminds me of this:
     

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  6. spidennis
    Joined: Feb 2007
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    Location: south padre island, texas

    spidennis Chief Sawdust Sweeper

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  7. Techecho
    Joined: Nov 2010
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    Techecho newbie to boat design

    I seen a cat built with two kayaks. The kayaks where made water tight, most of the mid span was trampoline but they did have a reasonable sized flat area with seats
     
  8. Manfred.pech
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    Manfred.pech Senior Member

  9. yoram
    Joined: Nov 2010
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    yoram Senior Member

    I hope I am not insulting anyone (trimaran lovers) but I do not see the advantages of trimaran for me. The converted Tornado catamaran was the closest I could get with what I wish for but I haven’t found a way yet to get all the details about it.
    I would still like to know all the the answers to the question I had before if someone could help;
    how much is its weight, where to locate the batteries, should i place the outboard electric motor at the back or should i make some kind of hole in the floor in the center of the connecting board to place the motor? (it is a light weight electric motor), where to place the connecting board in relation to the two pontoons, is it practical to have it only 4-5 meter (13-16 feet) long and how wide should it be in this length etc.
    anyone with some kind of ideas?
     
  10. rayaldridge
    Joined: Jun 2006
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    rayaldridge Senior Member

    If you put the motor at or close to the pitch center of the boat-- around midships-- you'll have less likelihood of the motor coming out of the water in chop. On problem with this is that the motor is no longer protected from spray by the hull. I suppose if this were an outboard-only boat, you could have a well in one hull for your motor.

    Here's what one of my builders did:

    [​IMG]
     
  11. cardsinplay
    Joined: Oct 2010
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    cardsinplay da Vinci Group

    It would be fun to see a list of boats where the prop was located at the pitch center.
     
  12. spidennis
    Joined: Feb 2007
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    spidennis Chief Sawdust Sweeper

    by me I saw a hobie 16 with a small outboard mounted just behind the forward crossbar. Never saw it out and about though ..... I'll have to keep my eye out for it again when out paddling my surfski ....
     
  13. rayaldridge
    Joined: Jun 2006
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    rayaldridge Senior Member

    Re outboard well at pitchcenter:

    I don't know about a list, but Kelsall did this with his smaller cats many years ago. Working small boats often have this arrangement. Where I live, the mullet boats (the ones that are left after the latest round of net bans) have this arrangement.

    [​IMG]
     
  14. DarthCluin
    Joined: Mar 2009
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    DarthCluin Senior Member

    There was/is a Hobie 16 powerboat on Craig's List.
    http://tampa.craigslist.org/pnl/boa/2056450117.html
    It looks like a very minimalist boat. Yoram its too far away to buy, but it may give you some more ideas.

    Richard Woods is developing a 20' power caramaran called Skoota. It may be more boat than you are interested in, but its worth checking out. Go here:
    http://www.sailingcatamarans.com/
    Then click on "New Designs".
     

  15. DarthCluin
    Joined: Mar 2009
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    Location: Florida

    DarthCluin Senior Member

    Here is a picture of the Hobie.
     

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