Minimum cruising cat-size & cost

Discussion in 'Multihulls' started by Alex.A, Feb 24, 2010.

  1. Alex.A
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    Alex.A Senior Member

    Doc - thought of going that route but your gains for size are what? Costs of mooring etc go up and accomodations etc get smaller - what about deck? Then there's the thing of having your weight in the centre and high up.... not good?
    I think for a podcat to have enough space - useable space - it needs to go BIG and that defeats the cost/simplicity concept.
    If willing to go to that length you'd be better off with a proa/tacking outrigger type boat.
    After much thought i am still "stuck" on a 9m cat being my best bet for now.
    Looking at a voyaging canoe style for simplicity.....
     
  2. Milan
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    Milan Senior Member

    Have a look at the Steve Dashew’s Beowulf VI, a lot to like and learn.

    http://setsail.com/catamaran-history-the-early-days/#more-10047
    http://setsail.com/multihull-history-how-cruising-started-for-us/#more-9951

    It is also simply and inexpensively constructed – hulls – 6 mm ply, square, box sections with semi circular foam bottoms. Crossbeams - standard aluminium extrusions.
     

    Attached Files:

  3. dacarls
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    dacarls Junior Member

    The Gougeon Brothers, JAn and Meade, have designed and built these boat types already.
     
  4. oldsailor7
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    oldsailor7 Senior Member

    Phil (Catsketcher) said:- As to speed - why bother. Speed is a furfy. Any well designed cat will go faster than the crew can take in 15 knots offshore. After this you will be slowing the boat down. You want a fast light wind sailor and a nice controlled boat in higher winds. You don't cruise fast so why the necessity to change?
     
  5. rob denney
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    rob denney Senior Member

     
  6. Gary Baigent
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    Gary Baigent Senior Member

    Thanks for the wonderful stuff by Steve Dashew, Milan. Those two downloads have filled in a few gaps of history. Steve's "philosophy" had a great influence here in NZ in those days, especially on Malcolm Tennant, maybe David Barker and Ron Given - and me too. The Bamboo Bombers and Great Barrier Express designs were following his Beowulf V and V1 approaches, as also were the Mickey Munoz surf cat designs.
     
  7. DocScience
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    DocScience Wishful builder

    RE: your truss beam for a 12m cat

    Could you give some more information about this "truss beam for a 12m cat." and what was involved in joining ??
    Do you have pictures posted somewhere ??



    There has been so much good information given by everyone, it takes a little time to read it all.

    I liked this vidio put in by rob denney post #158
    http://www.youtube.com/watch?v=8chR6DAFjGA
    It is just so amaizing to see what people have thought of.

    The folding cat would help with width, but length is still big for berths.
     
  8. Alex.A
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    Alex.A Senior Member

    Rob - it's the cost - not necessarilly of build - of length that is the problem. Ideally we would all want a 40'-50' boat - whatever type.
    Looking at Gaia's dream - gaia2 was close to what i was thinking but not much info on why he went back to his original thinking on design with the final boat.
    G2 was 12m/9m.
    Glenn Tieman built his Tama Moana for $14,000 - supposedly. 37' cat but not to everyones taste......
    Doc - have you seen Pookie - a Schacht concept proa - modern take on a Tepuke. Not sure about the inflatable tubes but i like the design concept.
    What about K-proa?
     
  9. captainsideburn
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    captainsideburn Junior Member

    Attached Files:

  10. rob denney
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    rob denney Senior Member

    Can't find any useful photos, nor a video of W (name of the boat) sailing. There is one on You Tube, but I don't know where. Sorry.

    W has a single beam and the hulls are free to pitch. The beam has bearings on each end so the hulls can move fore and aft relative to each other. The boa is adjustable from 7m-4m. Half the beam is a tube, the other half a truss, with bearings for the round beam to rotate in.

    The truss lengthwise and sheer pieces ares built from 19mm diameter pultruded carbon rod (ex sail battens for Tokio, the Whitbread 60). They are joined with carbon brackets we built in a home made autoclave using silicon moulds. As the truss part of the beam tapered, each of these was slightly different, so the mould had to be variable. We could have used much bigger pieces (basically a triangular piece on each side of each joint), but this would have added to the windage, and detracted from the fun. It is attached to the mast with multiple wraps of carbon tow.

    W is in Auckland NZ but has had a whole lot of extranei=ous stuff added to it so looks very different to what it originally was. The beam is still there, and still works.

    Trusses are great, but I doubt the extra work, and potential for failure from so many joints is worth the weight saving on a cruising boat. Easier to make a box or triangular section.

    rob
     
  11. rob denney
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    rob denney Senior Member

    Glad you have done your homework! ;-)

    Guess it depends whether you are going to live in marinas or not. For what it is worth, my boat has removable ends. It will break down to 7m long x 2.5 wide. This is for trailering, but it is a simple alteration to make it fold on the water. Not as simple as the Farrier method, but easy enough.
     
  12. Alex.A
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    Alex.A Senior Member

    Hi Rod - internet is a wonderfull place to look at boats and dream - but the more you see, the more you change your mind....all very confusing!!!
    No matter how much you trawl net - there's always more -aargh!
    Then to marry the budget to what you would like, compromised to what you can really have.....
    I live too far from the sea to trailer - for now at least. Working on that problem . Getting the design/build bug tho' ...... infectious i think - especially hanging around forums like this - full of "diseased" types :)
     
  13. Roger L
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    Roger L oldengineer

    In analyzing structures, solid-walled sections like the rectangular or triangular box beams can be viewed simply as surface trusses with the voids filled in.

    It's true that engineers are often taught truss analysis first because the countable joints make them easy mathematically. That is, the joints make trusses statically determinate. Conversely, any small section of a real box beam is indeterminate, and could be more complex except that if they are stiff enough we can make the approximation that the beam acts as one complete continuous shape.

    I'm with Denny. Box beams are better. Easier too.
    Roger L.
     
  14. oldsailor7
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    oldsailor7 Senior Member

     

  15. DocScience
    Joined: Apr 2010
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    DocScience Wishful builder

    trusses

    I have read these a couple times.
    Some things are difficult for me to visualize without a picture or diagram.

    Is it possible to either draw a few brief sketches on a piece of paper, scan it into a file on your desktop, and post it, or use "Paint" standard program on your computer, to make a rough drawing and post ??

    It would really help me, and maybe even a couple other people on this thread.

    Thankyou for the description.
     
    Last edited: May 6, 2010
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