Sango ripoff

Discussion in 'Multihulls' started by guzzis3, Sep 17, 2018.

  1. guzzis3
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    guzzis3 Senior Member

  2. VadimGo
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    VadimGo Junior Member

    is it not the price for the whole shebang with the molds and the property in? "couse otherwise the finish on those hulls should be awfully good for that amount?
    (Not that relevant, Boatsmith was quoting Wizzer hulls foam-glass primed, for under 30K US, 5 more for the trailer, 10 for the greatest folding mechanism... still well below...)
     
  3. waikikin
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    waikikin Senior Member

    I dont think Chris has ripped anything off there Guzzis3...

    Potentially the other way round in the greater scheme as has more production multis under the belt than the average designer.

    All the best from Jeff.
     
  4. guzzis3
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    guzzis3 Senior Member

    I'm not talking about the hulls, the hulls are irrelevant. How much is a set of 28' hulls ? $15-20k ?

    Mr Woods built the savanah and developed the wizard in the early 90's. To my knowledge no one had done anything like it previously. Using buoyancy to lift the hulls is genius and wizard sango require just 2 bolts tightened to lock the hulls in place.

    That thing takes a great idea and adds complexity expense and removes durability. How long are those rams going to last getting washed each launch and recovery ? Look at all the work to lock it up once the hulls are lifted. Really terrible.
     
  5. waikikin
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    waikikin Senior Member

    Then there's this

    & this
    this
    And the various iterations of folding tris.
    The approach of the hinged flange is similar to some folding masts it's good that some are having a crack at developing this "holy grail" solution to the inconvenience of transport.
    I had a close look at some of this stuff a decade or a little more my personal solution & not enacted was that simplest best to go demountable rather than folding and invest the time into the trailer- derrick and slide out cradles where the material cost was lowest to fabricate- the bolted beams in matched deck saddles with generous shaped washers. We had some reasonable interest but with the economic clock ticking loudly at the time and some variance in either cat v tri expectations v cost didn't proceed- looking back with some wisdom. Again my personal view was to develop the cat at around 7.5m as tooling costs very much lower. There's been some similar developed but again this dilutes and was unfolding at the same time & a very tumultuous period in Aussie boat building- had some vague offerings to assist some bigger players but took the safest employment path back into the commercial/work boat and larger charter repairs- that stuff is always there at good rates.
    All the best.
    J.
     
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  6. guzzis3
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    guzzis3 Senior Member

    I am familiar with Len Surtees boat and the cat2fold. Not sure what the third one is, I assume sliding beams.

    The issue I have with the boat I pointed to is it's a close ripoff of the Woods system, with no acknowledgement of Mr Woods work, but rather than being any sort of improvement it's a massive step backwards.

    I am right now modeling up a trailer with swing wings to spread the hulls and a central lifting platform ala sango to lower the bridgedeck into place. The beams will need to be moved by hand as will the mast but the idea is to have the outboard permanently on the bridgedeck and as little setup and manual labor as possible. The other thing about this idea is the boat once assembled can be lifted on the central platform, the swing wings folded in and the boat dropped to the ground or an inch off the ground during launch, providing for launching in thin water. Once I have a model done I'll post pics here.
     
  7. jamez
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    jamez Senior Member

  8. waikikin
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    waikikin Senior Member

    Hi Guzzis3, the third video I thought I was lining a collection of folders- this may be it here folding trailerable cat - YouTube https://www.youtube.com/playlist?list=PL67lRWoHk_mzVZuW3G-RBcj7lb8uF_Rwi
    The word ripoff may be far from fair & the efforts of Chris Williams may well outdate the evolutions of others systems- this I don't know for fact but old workmates spoke very highly of him. I'd have some misgivings around lots of folding systems and the potential for human interaction with pinch points within the various parts of system. Looks like some potential for that in the Surtees, Woods & the Albatross under discussion the X 2fold cat looks pretty gentle in action with out potential for gravity taking over and stored energy unleashing havoc.

    Looking forward to see what you're developing in the model- a great way to convey the ideas method & geometry. Are your trailer swing wings pivoting on a vertical axis? This seemed one of the best options when investigating the trailer geometries.. single pivot arms or double as can make some difference to trailer weight/balance through operation.

    Jeff
     
    Last edited: Sep 20, 2018
  9. guzzis3
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    guzzis3 Senior Member

    It is not clear to me whether Chris Williams developed the folding system or just the hulls. As I said I am not aware of an earlier folding cat that uses the Woods system but that Tennant does so if it dates from the early 80's then is is the earlier boat.

    The swing wings work like a parallelogram that spreads to a rectangle. So the trailer chassis has side rails. There are 2 bolts per side going vertically through these. There are 2 arms per side pivoting off the rails. Outboard the arms have another vertical bolt each which is connected to a cradle supporting the hull. Folded in the arms are near parallel with teh trailer side rails, folded out they are perpendicular. Yes it moves the hulls aft about 5' while splaying them 5' per side and shifts the center of gravity aft, but it also puts the boat further into the water as you back down the ramp and a tail heavy trailer at ramp speeds isn't dangerous. I guess the tow ball coupling could pop apart on a really bad day. Given the C of G should be fairly well forward for towing the forces should not be large.

    I'm doing proper engineering on this, first time I've bothered to do full calcs in decades, so it's taking a while. Had to blow the dust off my text books...so it will take a while to get it done.
     
  10. jamez
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    jamez Senior Member

    I found the article; its Feb 1982. In the article Malcolm refers to an American Viva design that folded down the middle (like the Maine Cat 22) to trail, but suggested that the hull folding under style should be quicker to set up as equipment in the center pod, nets etc could stay in place. He also designed a couple of 7 meter trailer cats with telescoping beams, but few were built. I spoke briefly with him about one of these, the Chevron (a handful of which were produced in glass here), he reckoned the electric telescoping trailer they built for the prototype almost cost as much as the boat!

    I don't think there is much that is completely new and suspect most of the folding cat variations have been tried more than once........
     
    Last edited: Sep 22, 2018
  11. guzzis3
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    guzzis3 Senior Member

    Yep it's been a topic of discussion for a long time. As you know I've been a big fan of Sango for a long time. Mr Woods got the details right which is the hard thing. Anyone can draw a hull and some beams, but getting the fiddly bits right...
     
  12. Clarkey
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    Clarkey Senior Member

    The Kelsall 'Amkats' have been around for decades too:

    [​IMG]
    [​IMG]
     

  13. waikikin
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    waikikin Senior Member

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