Demountable, 30+ to 40+foot Cat design?

Discussion in 'Multihulls' started by voodoo child, Feb 3, 2023.

  1. voodoo child
    Joined: Feb 2023
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    Location: indian ocean

    voodoo child New Member

    Hi to all.
    I am enjoying reading this forum since quite some time and learned a lot.
    But to be able to chose the "perfect" design for me, I would have to find a bit more specific answers to the questions i am still struggeling with.
    The cat does not have to be demountable, but has to be able to be build in parts. The hulls and nacelle have to be build completly, painted and finished than individualy transported a short distance, for assembeling by the waterside where it would be launched by crane.
    So a tube cat would be perfect, but the biggest i could find is Bernd Kohler`s KD105 KD105page https://ikarus342000.com/KD105page.html
    I like this design a lot but it would be "perfect" just slightly longer and a little more space in the hulls with maybe a little more payload.

    Any suggestion, idea and comment would be helpful and apreciated.
    Thanx regards Voodoo Chid
     
  2. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    One of the downsides to building this way is the boat needs to be taken apart and put together many times diring the build for this to work.

    It would be a rare cat that can be built all separate pieces and then cobbled together.

    There are a few Wharrams I believe that get close.

    My cat is fully demountable, but I don't really feel it was a good decision to build this way; despite the goals. The boat would take at least a week and cranes on each end and special cradles to move. I have the hull cradles, but the work is so much, I'd only do it for a permanent move to say California; even then Panama seems more fun.

    It doesn't seem awful, but, for example, I fitted the cabin base to the hulls; then had to remove the base, and finish the cabin off the hulls and then crane it back up and pay the crane company and pay a friend and build 20' fork extensions for a tractor. The time and efforts involved in administering to piece building are really awful versus adding transverse bulkheads and being done when they are bonded. We are talking about weeks of extra work, crane time and money.. My hull cradles cost hundreds of dollars and over a week to build; for example. The hulls with the bdeck on sit on the ground even.
     
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  3. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    Voodoo Child , if you want a cruiser then there should be no reason you couldn't widen the beam on the KD105 pod and flare out the hulls for more space , add a little length to the hulls for greater payload .
     
  4. Alan Cattelliot
    Joined: Jul 2021
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    Location: La Rochelle (Fr)

    Alan Cattelliot Senior Member

    TS3, first model by Marsaudon Composites. Demountable, sexy, and a lot of space. Initially designed for a raid on the Northwest Passage.

    TS3 Catamaran https://ts3catamaran.com/

    upload_2023-2-8_7-14-31.png

    I'm currently working on a similar boat, lighter and with a little extra power, for her to be sailed in Finland. I've you're looking for a more "modern" touch.

    Cheers,
     
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  5. guzzis3
    Joined: Nov 2009
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    Location: Brisbane

    guzzis3 Senior Member

    Richard Woods has a whole series of catamarans that do exactly this. He builds his designes and has faced exactly the problem you describe. He has a number of open deck models or his "cuddy cabin" designes that all can be built in parts and finished by the water.

    Sailing Catamarans - All Our Designs

    There are pages there showing him transporting a bridgedeck cabin boat on the diagonal to the water and the various designs that can be finished at the waters edge. Possibly start with the 29' saturn or the 34' Romany.
     
  6. waterbear
    Joined: Mar 2016
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    waterbear Senior Member

    Voodoo child,

    Be aware the payload is just the amount of weight that can be added to the empty boat until it sits on the designed waterline. Richard Woods, for example, assumes his boats will be somewhat overloaded for ocean crossings and designs extra strength into the structure to accommodate the extra load. Kohler may do things differently; you would need to contact him to find out.

    I will second Guzzi's suggestion of the Romany 34 (Here). This can be built in strip plank, has better advertised load carrying ability than KD105, and is probably closer to 50/50 cruiser racer than the KD105. I also think Woods is one of the most competent designers of self-build catamarans, you can read his bio here.

    I saw your other post in the multihull structure thoughts forum, quoted below.


     
  7. peterbike
    Joined: Dec 2017
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    Location: melbourne

    peterbike Junior Member

    Why not have a chat to Bernard about making the 10.5 , 10/15/20 % bigger ?
    Hulls with some flare above the water line, as Bernard has done with a few of his designs ?
    Maybe carbon beams for the greater loads ?
     
  8. Boatguy30
    Joined: Dec 2011
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    Location: St Augustine, FL

    Boatguy30 Senior Member

    The Romany is not demountable. It is capable of being permanently 'assembled" near the water after being build in another location.

    Richard told me he's unaware of any Gypsy and I think also any Saturns built as demountable. He actively discouraged me from trying to build a demounable Gypsy.
     
  9. jamez
    Joined: Feb 2007
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    jamez Senior Member


    Hi Fallguy, interested to know what design you are building. Any pics?
     
  10. jamez
    Joined: Feb 2007
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    Location: Auckland, New Zealand

    jamez Senior Member

    Malcolm Tennant designed some pure cruising tube cats up to around 40 feet (and more racing oriented designs that were larger).
    I don't know whether plans are still available for his designs, since he passed. But for the sake of an example: 11x6.8m 3700kg disp.

    NuiGuinea1.jpg NuiGuinea2.jpg
     
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  11. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I built a demountable Wood's Skoota. It is a nice boat, but needs a few changes and I'd not recommend demountable designs for something this complex.
     
  12. Christo
    Joined: Oct 2023
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    Location: Gig Harbor

    Christo New Member

    Alan Cattelliot , I'd like to learn more about your more modern touch on a TS3.
     
  13. Alan Cattelliot
    Joined: Jul 2021
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    Location: La Rochelle (Fr)

    Alan Cattelliot Senior Member

    Hi Christo,
    The TS3 itself has kind of a modern look, but rigging systems are of an ancient Time, when sails couldn't be closed properly. Forward cross, backstay, bigger mast, sailplane, I worked on the addition of some common features of racing catamaran.
    The client was willing to kept the total weight at minimum, meaning very spartan accommodations. Off course, the narrow hull shapes can be adapted to heavier configurations.
    I have seen in your profile that you have an F28. So you like multihulls, don't you ?
     
    Last edited: Oct 9, 2023

  14. Christo
    Joined: Oct 2023
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    Location: Gig Harbor

    Christo New Member

    Alan, yes, certainly, multihulls are my main interest, but also designs like class 40. I'm a fabricator, and looking for a new and modern design to buildand maybe bring to market as a kit boat. The f28 is 20 to 30 year old technology now. Im looking at what is new for 2023 and beyond. Some interesting candidates are the Black Marlin 33 (not available to builders) and a Schioning design. The TS3 looks interesting too, but I have little information on it so far. We are in a demountable thread, but my interests extend to folding tris too. If you want to bring the discussion offline I'm at christoatpuretimberdotcom
     
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