Slickest folder ever

Discussion in 'Multihulls' started by garydierking, Jan 14, 2012.

  1. dstgean
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    dstgean Senior Member

    Richard, any sneak peaks for your website? I'm thinking of doing a solo + boat (me + gear for a weak including fresh water or me and a passenger for a daysail). You work always inspires me, and I think a small tri might work well for a solo + concept. Will aux power be a paddle? Have you seen some of the boats being designed for events like the EC that are using the Hobie Mirage drive for aux power? Often in diminishing breeze guys will "motor" sail and pick up quite a bit of efficiency that way.

    Dan
     
  2. upchurchmr
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    upchurchmr Senior Member

    dstgean,

    You beat me to the request to Richard, of course he is a pro, sneak peaks might take food off the table, but I can ask, and he can decline, no problem.
     
  3. upchurchmr
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    upchurchmr Senior Member

    Frank,

    I might ask the same. You said you are already working on the next boat. How about an outline of your ideas for the next one?
     
  4. Richard Woods
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    Richard Woods Woods Designs

    My problem, as you say, is that I am a "pro" so I need to earn a living from my designs

    Unfortunately I will never do that with a 15ft trimaran, but I can with bigger boats. So my small boats are for my fun - which is why I build and sail them myself. Currently I am very busy with three large designs and my 15fter is something I do when I want a break

    I will post here when I have something. But for now my concept is to have a trimaran version of this

    http://www.youtube.com/watch?v=GtqkhF8BW5Y

    So as I say, something different from what DIYtri Guy is doing.

    On the aux power problem. I have got a Scullmatix see here

    http://www.duckworksbbs.com/gear/scullmatix/index.htm

    which I will try on my Strike 18 soon. But I have also considered this

    http://www.youtube.com/watch?v=ujSHHUlnk08

    rather than the Hobie flipper fins. I think its more efficient to rotate one legs like on a bike, rather than use a to and fro motion. And the propellor can go in reverse

    We'll see, it will be fun sailing and I do hope to get to the EC and Texas 200 soon.

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  5. WillyG

    WillyG Previous Member

    The Mirage can also go in reverse. Just lift the unit up, flip it around 180 and drop it back into its trunk. It will also work in much thinner water than will a leg powered prop.
     
  6. DIY Tri Guy
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    DIY Tri Guy Junior Member

    Wow, lots of strong opinions about leeboards! So many good points made on both sides. Thanks Richard for your kind words. Our water here is VERY skinny, expecially where we have to beach-launch. Often it's as shallow as 4"-6" for the first 100 yards. 3 feet would be a great luxury. I see monohull (and daggerboard) sailors having to walk their boats out a long ways before they can get in and sail. But my boats can sail effectively in 6" of water (Laura's boat in 4"!) It's kinda cool to be able to sail right by these folks :)
    OK, since I started this mess, I should probably respond to every point above, but I'll just make a few simple comments. If you are thinking about "Bolger style" leeboards, mine definitely aren't that. They are quite firmly attached to the side of the hull, well above the waterline. They don't flop, make zero noise either underway or at rest (other then a nominal splashing now and then), and slice through the water quite smoothly. They don't need weights to hold them down. I use a large friction washer to hold them exactly where needed, and they don't move from there unless they hit something solid.
    Yes, leeboards are wave-piercing foils. But it's amazing how smoothly they slice the water when angled back 30-45 degrees, which is where I normally keep them. And if you get them a few inches away from the hull, the interactive turbulence goes away, leaving you with a smooth, quiet, and dry experience.
    Now, I'm the first to concede that a daggerboard can be more effecient. Its location provides several advantages. If you have lots of deep water everywhere you sail, and you don't mind the other disadvantages, daggerboards are great. If you're into squeezing out every ounce of performance, then daggerboards are for you -- provided the hull and boat are professionally designed and you never plan to use more than one sail rig, as you are now stuck with a basically non-adjustable CLR.
    Ultimately, it's all about your individual priorities. Mine are: simplicity of construction and operation, quick & easy to rig, painless and exciting to sail, quick, dry ride, nimble, NO hiking out, smooth ride, and quiet (both main hull and amas).
    I don't pretend to be anywhere close to a professional designer or builder. I'm just a fascinated amateur. My boats are designed for my likes and for our local waters. They have evolved over the past 30 months to be pretty much optimized for both. Will they continue to evolve? Absolutely. Will my priorities change? Probably. Will they ever be intended for offshore or "hair on fire" sailing? I don't think so. I really don't enjoy the white-knuckle sailing experience, but I gladly leave that to you folks who do.
    So, for all the reasons noted in my article, I stand by my conviction to leeboards. For the kinds oif water we Gulf Coasters sail in, they just can't be beat. Of course, as I said before, a leeboard MUST be well designed and well built -- the subject of my next article.
    - Frank
     
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  7. WillyG

    WillyG Previous Member

    Sure


    Ask Google about foam sandwich construction. Drill in to the process of building foils and structural components with the use of vacuum infused resin and carbon uni cloth for load applications.

    If you assemble a foil and its trunk in this fashion and engineer it to be strong as well as light, you will see that there's little difference in the overall weight needed to mount a leeboard to one's boat.

    It's critical to understand that a surface piercing foil, like a leeboard, is only supported at its pivot point. DIY stipulates that he likes to move the foil away from any hull generated turbulence for his best performance. This means that the board is unsupported for virtually its entire length above and below the surface.

    When the sail is heavily powered-up, this generates a large lateral load on the boat, the mounting structure and down through the foil. That load has to be absorbed in some fashion. Typically, it is partially absorbed by the hull itself at the mounting point, (however that may be effected design-wise) then the pivot point locus and then lastly, the foil span and section thickness.

    The bigger the sail and the heavier the boat's displacement, the stronger all of these items need to be in order to prevent failure. By far and away, the majority of leeboard setups I have seen are fashioned from solid wood.

    Let's assume that the board is made of White Ash, that the leeboard thwart (if that is the chosen method for mounting the board to the hull) is also Ash, or White Oak, the mounting hardware for the fastening of the thwart and the pivot bolt/washer, etc. Well, all this stuff adds-up to a substantial piece of weight. There are other methods for building and fastening a leeboard, but they require that the boat builder allow for the high, point loading effect on the hull at the location of the pivot mount. Either way, It can be a large load being generated. If one were to add the effects generated when sailing in larger swells and heavily gusting conditions as multipliers, (the regular stuff one sees in the typical EC) then the loads being pushed through the leeboard mount point can get extremely high.
     
  8. ImaginaryNumber
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    ImaginaryNumber Imaginary Member

    1 person likes this.
  9. WillyG

    WillyG Previous Member

  10. spidennis
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    spidennis Chief Sawdust Sweeper

    Well I don't think it's exactly a "Tribal Menace" like the designer predicted and if the end result is the XCR then it seems like a simple enough design to keep complications to a minimum for such a "challenge", though I do look forward to it actually finishing an EC this year. It's been 7 years now since the writing of this article and I wonder why the designer Chris Ostlind himself hadn't yet entered an EC himself to prove his theories? He seemed so dang sure it was gonna just kick everyone's butt! Though I doubt he planned on the likes of Randy Smyth to enter the picture and smoke any and all challenging competitors. Like I said though, I do look forward to the xcr actually finishing but it's mostly up to the competitor himself and as he reports as of a few days ago he's gun-ho for the finish line this year!
     
  11. Richard Woods
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    Richard Woods Woods Designs

  12. upchurchmr
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    upchurchmr Senior Member

    Richard,

    Will the 15'er have enough sail to be on a similar edge? Hopefully it will have enough sail to give a real thrill. Probably 2x due to the increase righting moment on the tri?
     
  13. rayaldridge
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    rayaldridge Senior Member

    This is not necessarily true. Leeboards, for example, can have their pivot point below the gunwale, and be supported at the gunwale by a structure that sandwiches the top of the board between a rail and the hull. Very strong, very light, and the structure need not be very long, since the board's top does not rotate very far away from the pivot point. Michalak's Laguna design uses a system like this, I believe.. If the pivot area is reinforced as part of, say, a thwart or a frame, then the extra weight required to mount a leeboard is very small indeed.

    Other kinds of surface-piercing foils, such as a central board on a cat, can be as well supported as a conventional centerboard.

    Whether or not a foil is surface-piercing has little to do with how easily it's supported against lateral forces. Consider, for example, an outboard rudder.

    My personal opinion is that leeboards are inferior to daggerboards in performance terms, but there may well be practical reasons for accepting less efficiency, as Frank says.
     
  14. rayaldridge
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    rayaldridge Senior Member

    I don't.
     

  15. Richard Woods
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    Richard Woods Woods Designs

    Currently the drawings shows a 10.8 sqm mainsail and a 3.8sqm jib on a 6.5m mast

    That's as big as I want to go bearing in mind I expect it to be sailed as a singlehander as well as with a crew. So its actually less sail than the B14 I showed you earlier. More on the lines of a RS400, which I have sailed at 15 knots.

    Dinghy mainsails get to be a handful if over 10sqm (especially at my age) and a 4sqm jib is about the max before you need a 2:1 jib sheet

    I don't consider taking out a drive, turning it round and putting it back in as a "reverse" gear. But I suspect I'll start with the Scullmatix in part because I've always wanted to try a yuloh

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
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