Small trailerable cruising cats... biggest flaw?

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

  1. rayaldridge
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    rayaldridge Senior Member

    In my opinion, it's the difficulty of folding them in a way that is as simple and fast as folding small trimarans.

    A number of ingenious solutions have been tried. Among the best are Richard Woods' cats that have all accommodation in the center deck, and fold the hulls under that deck for trailering. It's a great solution, especially considering his out-of-the-box solution to ergonomic comfort at anchor-- his drop floor.

    My objections to that approach might not matter to lots of folks, but I would prefer a solution that didn't involve tipping the hulls over, and that preserved the open bridge deck, which in very small cats is really nice to have, for a deck tent that can greatly expand the interior at anchor. I'd like to have all accommodations in the hulls, for lower profile and wind resistance, while still retaining sitting headroom below. I'd also like a solution that allowed the boat to be folded on the water, so it could be kept in a narrow slip. Lastly would be a way to fold the cat without having to lower the mast, so that unfolding to sailing beam was a matter of a couple minutes, instead of the hours it generally takes most trailerable cats that fold or demount.

    All these problems have long since been solved for trimarans. Cats are a more difficult engineering problem, I think, but I wonder what progress can be made?
     
  2. SerjKu
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    SerjKu Junior Member

    If to contemplate this problem on an example of projects R. Woods it is possible to tell that Wizard and Sango are easily turned off. But they look not so attractively (UMHO). Merlin, Strider, Skua look much better (UMHO). But for this purpose that they would be convenient in transportation and deployment, extras are necessary.
    And it simply catamaran of my acquaintance

    P.S. I am sorry for my bad English.
     

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  3. 4sail
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    4sail Junior Member

    A great looking trailerable catamaran, SerjKu. Do you any information that can be posted?
     
  4. rayaldridge
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    rayaldridge Senior Member

    Yes, I'd be interested in knowing how it folds.

    I don't think my list of design goals is unreasonable, but I can't seem to find a design that fulfills that list.
     
  5. AnalogKid
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    AnalogKid Junior Member

    Ray, have you looked at how some of the Wharram owners launch their trailerable-sized Tikis?

    The beams are retained in tubular sockets on the deck of each hull. On the trailer, small 'dummy' beams are inserted to keep the hulls upright and together. Once launched, the front and rear beams are replaced with the full-length sailing beams while the centre 'dummy' beam is retained. The full-length beams are lashed at one end while a line with double purchase is used to drag one hull to the far end of the beams. Once the front and rear beams are lashed at both ends, the centre beam is also replaced.

    Obviously no deck is in place while all this goes on, the deck boards being sectional and put in place after the boat is 'expanded'. But what if the open deck could be made to concertina down between the hulls in the folded position?
     
  6. Steve W
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    Steve W Senior Member

    Analog,what you describe is much the same system that was used on my Macgregor 36,i built a telescoping trailer that allowed it to all happen on the trailer,it is however more of a transportable cat rather than a trailer sailer
    Ray, Roger Simpson had a design for a folding cat that used ladder style crossbeams that had some depth and hinged in the middle and at the hulls,i think the center of the aft beam went aft and the mast beam went fwd,the tramp stayed laced to the hulls and there was a solid link bar that connected the beams together in the center.The boat was about 24ft i think. I dont know if the design is still available.
    Steve.
     
  7. rayaldridge
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    rayaldridge Senior Member

    Analog-- that was sort of the same system as my old Wharram Tane, except that the old system was a lot less convenient. There were transport beams and sailing beams, and these had to be switched after launch. What made it worse was that there were two forebeams joined by a slat deck, and two aft beams, also with attached deck. Even when I was young and strong that was a pain to manhandle. I had to lash temporary 2X4 beams to the gunwales to keep the hulls from tipping over when they were freed from the transport beams. It took half a day to launch the boat, and it wasn't any fun.

    Steve, the Simpson design sounds a bit like something I'm considering. Do you know how the hinges were reinforced to take strain? I'll try to look up the design. Simpson seems to have been sort of an unrecognized and under-regarded pioneer.
     
  8. SerjKu
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    SerjKu Junior Member

  9. SerjKu
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    SerjKu Junior Member

    I the —Āatamarano-dreamer, but at me "a hole in a pocket".
     

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  10. CatBuilder

    CatBuilder Previous Member

  11. Steve W
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    Steve W Senior Member

    Ray,The Simpson design im thinking of was called the Takeaway and was designed in partnership with an Alan Dowd,na. The beams are trussed metal and look like they are at least a foot and probably have full height pins,3 per beam.
    Steve.
     
  12. jamez
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    jamez Senior Member

    I enquired about this design some years ago, was told (by Boatcraft) only one was built at that time (early 2000s iirc). from the study plans i have the hulls are quite roomy, for a 24' cat, and flared so the waterline is relatively narrow - sort of like a scaled down Backslash. The folding mechanism/beams are welded aluminium. You could check with Boatcraft Pacific for plans availability.
     

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  13. rayaldridge
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    rayaldridge Senior Member

    Thanks much, guys-- very useful information. Massive-looking weldments on the Simpson-- ought to be plenty strong.

    The boat I'm drawing now is intended for simple amateur construction (I'm a simple-minded amateur.) It's 19 feet 8 inches, and should weigh 800 lbs on the trailer. The idea was to come up with a design with more sailing beam than a Jarcat or other small fixed-beam cats, so a recycled beach cat rig would drive it adequately and safely, and a compact car could pull it. I probably need to use a slightly different approach. I'm trying to figure out a variant on the same approach Simpson used, but with wood and epoxy. Also, that approach, at least as shown, doesn't allow you to keep the mast up when folded, unless I'm misunderstanding the pics and drawing. That's a tough nut to crack, especially with the rotating mast I plan to use. But great food for thought. I really appreciate you guys going to the trouble of posting the info-- it definitely helps me.

    SerjKu, what a fine-looking cat! I like the central pod for the motor. Looks very fast, but I was impressed at how dry the boat seemed to be, even in that heavy air. Nice!
     
  14. AnalogKid
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    AnalogKid Junior Member

    How about building the folding mechanism strong enough to keep the hulls upright on a mooring, then 'reinforcing' them with additional inverted U-section beams slipped over the top and pinned in place. It would allow the hinges to be built on a more managable scale.

    To my mind, the hardest part in this exercise is figuring out how the deck is to be folded or stowed and then replaced when going to and from narrow-beam format.
     

  15. Fanie
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    Fanie Fanie

    You can look at 'cattofold' as well
    http://www.cat2fold.com/

    One of my designes has the front and rear beam one end each attached on a pivot so that both beams can swing into the length of the boat, but it requires flat-ish hulls.
     
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