Fanie's Folding Cat

Discussion in 'Multihulls' started by Fanie, Feb 22, 2012.

  1. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Who's the second boat for :D

    I'd rather say one boat and fill the space up, bigger boats are more fun and you can do more for longer on the water. If one does it well it's no more difficult or tricky than a small boat, we have winches and stuff nowadays...

    The max trailer width is 2m500. With the deck slide over the hulls you can go to about 5m, but you have to remember the deck is part of the beam structure now, or it will fold in the center of the deck sagging into the water. You also want the cat to be stiff, capable to resist when supported only on the oposite ends...

    I've had another idea and that was to have the deck or cabin or whatever you want as a one piece riding on the deck when you trailer. The beams are loose aluminum round tubing that gets inserted before the launch and the deck is located in the beam center, then once in the water, the hulls are pulled into position and clamped. Not too difficult to make locating snap down clamps.

    The reason I chose the above is the storage space in the deck, it takes al the loose extra's out of the hulls, including the smelly fuel. I can live with the hight, a PVC canvas cover is good enough for protection. I also like wide cats with lots of deck space. You can also add a canvas cover for sun protection, but canvas in wind is cold and noisy.
  2. spidennis
    Joined: Feb 2007
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    Location: south padre island, texas

    spidennis Chief Sawdust Sweeper

    Two boats, yup. The first one is my prindle 16 proof of concept boat where I can get everything working, then I'll know more about what I want my hulls to be and either find a set of plans or have plans made for me, hence the second boat, then I can run one against the other to tweak out details.

    Our boat's missions are quite different, mine has to be small for portaging and for some of the tight waters it will get into while in the folded position. I have thought about a bigger boat, but that comes much later.
  3. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    having to move the masts before folding is a real bummer. Why don't you just place them over the pivot point of the forward beams, or better yet, mount one mast on the forward beam ?
  4. spidennis
    Joined: Feb 2007
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    Location: south padre island, texas

    spidennis Chief Sawdust Sweeper

    What i'm using amounts to windsurfing gear so that's pretty light, it's also freestanding so no rigging of any kind. Being biplane rigged means I can go smaller with the sails. Initially I'm going to use a Hobie Tandem Island sail, and if I can find another to borrow then I can test out a pair of them.

    I could mount the mast base on the outside of the hull and pivot in the middle so that the beams would miss the masts, it's just one of several different combinations that I've played with. Playing with the model helps see what's what.

    Per the rulz I have to be able to reef and rolling furling makes that easy, but not an optimum sail when reefed, it's just easy. I'd really like to use windsurfing gear and I can get a 8.0 sq meter sail size fairly easy enough but it doesn't reef so can't use it.

    attached is a pic of a guy using both hobie sails, the bigger TI up front and the AI behind it.

    Attached Files:

  5. bill broome
    Joined: Jul 2008
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    Location: sydney

    bill broome Senior Member

    it's fun to try and square the circle, but the truth is, in the 6-9 meter range, folding tris are the way to go.
  6. Wynand N
    Joined: Oct 2004
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    Location: South Africa

    Wynand N Retired Steelboatbuilder

    Jeez Fanie, why not just float a large caravan with top deck fitted for the braai (bbq) and beers:D You surely want to pack a lot on the boat and then expect it to fold up in a suitcase, double berths et all :confused: And if I may ask, why the double berth when go fishing with a pal :confused::D

    I have an idea; why not build the deck rigid consisting of two parts 2.4m wide that pivots along the centreline to fold. This will give you the required 4.8m beam and still be legally trailer-able. Another spin of this it will be easier to fold the interior away as well in two large "deck shells".

    What about the hulls I hear you ask? Simple.....
    Make two inflatable pontoons (like rubberduck but larger) and glue the onto the perimeter of the decks (folded open) longitudinally. When transporting the contraption the pontoons are deflated and basically stows away flush on the deck edges - one below on half and the other on top of other half deck when folded. The best part of this method is the the overall height of the "boat" towed when folded is relatively low and will tow easily and much lighter since it has no rigid hulls. And the folding mechanism is a simple hinge affair with positive lock.
    A small electric battery driven pump will fill the pontoons in no time and you can have a few flotation chambers in the pontoons to make it safe.

    But I would rather have my boat loaded with other comfort features when going fishing - see pic below :D:D

    Attached Files:

    • Boat.jpg
      File size:
      39 KB
  7. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    One of the likings (for me) of the mast right at the back is it is really easy and simple to put up or remove. We visit different venues and not all are suitable for sailing, nor is there always wind.

    On some venues you would defenately leave the mast and sails at home and just use the iron sail(s). Other venues the sails is a bargain if you want to travel longer distances without the fuel expense, or simply for sailing for the fun of it.

    I built a tri, and it was ok, but cats give a different (more) comfortable space which I like more. A tri is too much like a mono that is wide.

    Ah you see Wynand, no space for you on that boat ! Nice picture, one day when I'm big I'm also going to have a crew like that ! If anything that was a nice motivation to get the boat going ;)

    One thing that frustrates me on narrow multihuls is you have little moving space, especially when you're fishing. Rough water is also less of a problem on wide cats.

    On the tri-yaks, I could have put them side-by side, but stability wouldn't be the same, not even close. Beeg difference betwen 1m600 and 4m !

    I actually had a look at a 5m hobie over the weekend. The thing is only 2m wide (why ???) I was thinking if it was foldable and 3 or 4m wide you'd spend less time righting the damn thing since it won't get blowed over so easily. Some probably like the risk of capsizing so why not make them 1m wide :D
  8. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    One more thing, inflatable hulls are not an option, I want to berth (sleep) on the boat. The hulls are the best space since a hull is a rigit and more ideal place for berthing. Tents are noizy and cold in bad weather, they're just ok for shading the sun.

    Even if the weather turns for the worst you can just anchor the boat, and retire to a comfy horizontal position, gooi 'n dop and watch a nice movie, read a book, catch up on some sleep or waste cropped up energy on the crew members :D
  9. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Redheart Rum & Coke ;)
  10. rayaldridge
    Joined: Jun 2006
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    Location: USA

    rayaldridge Senior Member

    This is only true if ease-of-engineering is your main design goal. In most other respects, cats make better cruising machines. That's why an inexpensive trailerable cruising cat is the Holy Grail of small multi design. As I see it, the main advantages that folding tris have are:

    1) Much easier to devise a folding mechanism that works well, can be folded for use in narrow slips, allows for dry sailing (storage with mast up), and is inexpensive to build.

    2) Cabin sight-lines. Because of the limitations of highway trailing beam, cats suffer from the infamous tunnel hull syndrome, which makes trailerable cats claustrophobic.

    These problems have yet to be solved in cats much over 6 meters, but it's only through the efforts of guys like Fanie that these problems ever will be solved, which is why I applaud his efforts, and pay attention when he posts stuff.
    1 person likes this.
  11. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Thanks Ray, but I don't have any money :D

    I'm in the school just like every one else, but thanks for the compliment anyway. I was rather hoping one of you guys would come up with the best solution, and save us all a bunch of time ;)

    I'll ask the wife. She knows everything LOL.

    What irritates the daylights out of me is every now and then someone comes up with a very simple solution that works exceptionally well. How can you have missed it, it's so logical...
  12. oldsailor7
    Joined: May 2008
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    oldsailor7 Senior Member

    Yeah! Like in Cats---the Jarcat.
    In Tris ---the Nugget.
  13. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    What width for a hull is too narrow ? I know it's a relative question, but there should be a rough approximate where it would be considered acceptable.

    Then the next question would be what can one do to make a hull appear wider or feel less claustrophobic ?

    No, mirrors above the berthing won't do it :D
  14. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    Any news on this design issue?

  15. prograd
    Joined: Oct 2012
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    prograd Junior Member

    Maybe you could make 2m wide flare to bridgedeck, and then fold the other hull under the first one. This way you could double the space in one hull, but the other one wouldn't be useful anymore.
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