Dinghy Design: Birth of Two Raceboats-K3 and Shaw4.0

Discussion in 'Sailboats' started by Doug Lord, Feb 25, 2013.

  1. Doug Lord
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    Doug Lord Flight Ready

  2. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    Shaw 4.0

    This dinghy is being pushed by one guy-"Fraser"- who has assembled a team from designer to builder and who has tried to involve others in the design on Dinghy Anarchy. Build photos and more on website: http://www.shaw4.org/

    The Design and Build Team

    Rob Shaw of Shaw Yacht Design
    In recent years Rob Shaw has proven himself with an array of very successful designs. He boats are both extremely fast and very well behaved both upwind and down.

    Robs sport boat designs are cleaning up everything and his boats are ‘giant killers’. Rob Shaw has a special eye and knowledge of what makes a boat fast. He is, on one hand conservative but he is also looking for every advantage as defines and refines the design.

    Alex Vallings of C-Tech
    Alex’s company C-Tech is a well-known carbon mast maker. His masts have won many national and world titles. Alex is an 18 footer sailor and recent won the Nespresso 18ft Skiff title in San Francisco. We all know how important the mast is in performance and Alex has the experience, knowledge and capacity to deliver.

    Andrew Wills & Derek Scott of North Sails
    Andrew is a World Champion sailor and coach, Andrew has raced one design boats since he was eight years old, moving from an Optimist through the National classes to the Laser Olympic class, winning many titles along the way. He has in September won the North American Etchells championship.

    Derek is the current 3.7 single handed skiff national champion and North Sails one design specialist.

    North sails are an impressive organization that has the technical skills and resources backed by talented people. These people live and breathe sailing.

    Craig Partridge of Partridge Yachts
    Craig is the ‘Master of Carbon’ coming from a boat building family and the builder of choice for hi-tech carbon racers. Craig owns and races the Shaw design ‘Animal Biscuits’ Craig of Partridge Yachts can do anything with carbon. His work is nothing short of stunning. The build quality he will deliver will create a world class boat.


    click--
    Pictures-two renderings and a very recent picture of the prototype and the Sail Plan:
     

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    Last edited: Feb 27, 2013
  3. Doug Lord
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    Doug Lord Flight Ready

    Shaw

    Boat is painted-looking good:
    click-
     

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  4. Doug Lord
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    Doug Lord Flight Ready

    New Shaw pix today:
    click--
     

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  5. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    Shaw 4.0

    Here are the first pictures of the new carbon unstayed mast-amazing how it strikes you the first time-looks good!
    click for larger-
     

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  6. Petros
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    Petros Senior Member

    on one of the videos you posted the designer made a statement I would like to elaborate on. He said since these boats almost always planing he eliminated the rocker out of the hull. looking at the lines it indeed looks like it is almost a straight line from the bow to the stern on the bottom.

    It appears he expects it to come up on plane faster without any rocker, if that is true why would you put any rocker in a racing dingy? would no rocker make steering it as low speed slow/draggy? I always understood rocker to help maneuverability, but now that I think about it, it also allows the water to move around the hull better when in displacement mode (lower speeds). So would having no rocker mean it will not perform as well at slower displacement speeds?

    Anyone want add anything, or correct my assumptions about the design of the is hull?
     
  7. Doug Lord
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    Doug Lord Flight Ready

    Both Steve Killings 14 and Shaws 4.0 dinghy have what seems like minimal rocker. Now, whether or not that affects manouverability or not is going to depend a lot on the shape of the rest of the hull and its sailing weight and how far(if any) the ends are immersed. It's known in dinghy design that less rocker coupled with a relatively flat planing surface should lead to early planing. But the I-14(the only one with videos) is generally speaking a displacement hull upwind though it is "assisted" by the Bieker foil. That coupled with the rounded sections aft(see middle video) should allow for good manouverability upwind between 6 and 9 knots*, it seems to me. Without knowing how much the ends are immersed its hard to comment-its doubtfull the 14 or Shaw has zero rocker.
    The Shaw doesn't have the athwartship roundness aft of the I-14 but the bottom is turned up a bit on each side.

    * Upwind top(more or less) speed
     

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  8. sean9c
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    sean9c Senior Member

    Are you saying that I14's don't plane upwind? If so, I don't think that is correct.

     
  9. Doug Lord
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    Doug Lord Flight Ready

    I-14

    =====
    Bieker says:
    D/L ratio=97
    SA/WS=4.3
    Approx. speed upwind in breeze =9knots(S/L ratio=2.4, Fn==.72
     
  10. Doug Lord
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    Doug Lord Flight Ready

    Shaw 4.0

    Fraser is about to test sail the new Shaw 4.0-hopefully tomorrow in the Bay of Islands near Auckland. Should have pictures and video in a couple of days.
     
  11. Skyak
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    Skyak Senior Member

    I think the reduction of rocker goes with the high average speed of the design or race. The sail area is so large and controllable that more races will be won based on planing performance than on displacement performance. The T-foil rudder allows them to dial in trim so the flat bottom can generate maximum lift. I wonder what the minimum wind is for a race? I also see on the I-14 that there is no place to sit on the rail -I think in those conditions they sit on shore.

    Higher speed and long high aspect ratio foils on short hulls means that rocker is not needed to improve tacking. I think the tricky part on these boats is keeping the boat upright so you continue planing through the tack or gibe. It has to be fast but you have to maintain balance while you move from one trapeze to the one on the other side of the boat.

    I am not surprised by the lack of rocker. At this point I wonder if a completely flat aft is desirable.
     
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  12. Doug Lord
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    Doug Lord Flight Ready

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