New design, 15' cat ketch

Discussion in 'Boat Design' started by 176inches, Apr 24, 2012.

  1. 176inches
    Joined: Apr 2012
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    176inches Junior Member

    A year ago I started building a 15-foot open sailboat that I designed myself, using Carlson Design software and lots of calculations. It is constructed of marine plywood, cedar and oak, using broad lapstrakes (4 strakes per side) glued and nailed. The rig is very traditional: cat ketch with short unstayed wooden masts, standing lug sails and sprit booms. I constructed the spars and sewed the sails, and made a pair of poplar 9-foot oars also.

    Aerie is now ready except for the running rigging. For those so inclined there are plenty of photos and commentary on my blog (http://176inches.blogspot.com). The handle is from the length of the boat per the plans (the finished length is closer to 179 inches).

    Any questions or comments welcome.
     

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    Last edited: Apr 24, 2012
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  2. Doug Lord
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    Doug Lord Flight Ready

    Thats a sweet looking little boat! Congratulations! Have fun....
     
  3. Wayne Grabow
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    Wayne Grabow Senior Member

    Well done. Plenty of steps there, and you did it all yourself. Isn't it a great sense of accomplishment to see it through from a vision in your mind to a finished product you can use and appreciate?
     
  4. 176inches
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    176inches Junior Member

    Thanks, Wayne. That was the whole reason for embarking on the project. Now I have to see how she sails...
     
  5. 176inches
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    176inches Junior Member

    Thanks, Doug. Can't wait to see how she behaves in a good breeze.
     
  6. Tad
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    Tad Boat Designer

    There's the rub........good luck.......do report on how she goes......
     
  7. messabout
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    messabout Senior Member

    Nice looking job. Congrats for finishing the project so attractively.

    From the pix here and on your blog, the boat looks narrow, high sided, heavy, and maybe tender. What does the mid section look like? Flat bottom steeply beveled chines?

    Sprit boomed lug is out of the mainstream but I think some of the Aussie and Kiwi boats have used that rig, but not usually in split rig planform. The mizzen pole looks pretty tall. That implies that it will have a good sized sail and that you will use it for drive as well as trim.

    We await your reports about sailing quality.
     
  8. 176inches
    Joined: Apr 2012
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    176inches Junior Member

    All this may be just effects of the camera angle (the cross-section gets steep and narrow near the bow). The beam is a full 6 feet (compared with 15 feet LOA). The sides are rather high but I wanted lots of freeboard for Lake Erie, which can get rough, and ultimately for the Aegean Sea, plus good displacement (it's about 950 lbs at the design waterline). Tender? I'll have to find out; but the righting moment is at least 550 foot pounds (per the design software, depending on load), and the 50 lbs of lead ballast along the keel batten should help a lot. I still don't know the weight (around 350 lbs with ballast I would guess); looks could be deceiving since almost all but the frames is 1/4 inch plywood. The basic section profile is very well-rounded, with a shallow V bottom (garboards are each about 8.5 degrees off the horizontal). This basic 3-view from the software should give you a better idea.

    As for the rig, yes, getting a balanced helm dictated a large and functional mizzen sail (only 7% smaller in linear dimensions). The low centers of effort and gravity of the rig should help stability too. And I designed her for beauty, tradition and leisurely sailing, not racing. It all remains to be seen.

    Thanks for the constructive comments and questions.
     

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    Last edited: Apr 25, 2012
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  9. 176inches
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    176inches Junior Member

    Two more photos will illustrate what I said above. Four of us lifted Aerie
    very easily--of course I added decking, flooring and ballast since, but still. And the profile and width are much clearer.
     

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  10. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    looks like a really nice boat and rig.

    Just don't understand the need to put roach in the leach of the sails.
    Unless the battens to hold that roach are full length, they may make furling and reefing more difficult.

    And the roach doesn't add sail area to a rectangular rig like it does with a triangular one.
     
  11. PAR
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    PAR Yacht Designer/Builder

    A hull of those general dimensions, if well thought out, will weigh about 300 to 350 pounds. You can get this down to 200 to 250, but it takes some design skill and risks some durability.
     
  12. 176inches
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    176inches Junior Member

    Thanks, PAR. I expect you are right I'll have it weighed at a quarry nearby as soon as I get a license plate for the trailer. I am very curious. I think it will be nearer 350, what with the ballast, benches and cedar plank flooring.
     
  13. 176inches
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    176inches Junior Member

    Good questions that I considered at length myself. Well, the inspiration was from John Welsford's Houdini, which has even more roach. Reefing should not be a problem: the lowest batten is above the reef line. As for furling, the battens are arranged radially so I am not worried too much. It does in fact add quite a bit of area by making the lower trapezoid (up to throat level) wider at the top. I like the way it looks too.
     
    Last edited: Apr 26, 2012
  14. 176inches
    Joined: Apr 2012
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    176inches Junior Member

    I had accidentally started two threads (because I thought the first one had not gone through) and couldn't shut one down. By now an administrator has consolidated the two into this one and closed the other. Apologies to all.

    I do promise to keep you posted on how the boat performs. First I have to do a very small amount of detail work on the sails, and then install the running rigging. Then (or simultaneously) I will test the boat for flotation, stability, and sculling/rowing performance at the city reservoir (it's only one square mile). Then I have to get it inspected, titled, taxed and all that. Then it will be off to Sandusky or Maumee Bay on Lake Erie for the first sailing test, hopefully with a very experienced friend. So do keep checking both here and at my blog (http://176inches.blogspot.com). Thank you all for your encouragement and curiosity.
     

  15. 176inches
    Joined: Apr 2012
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    176inches Junior Member

    I have finished the boat's rigging. Check out my blog at http://176inches.blogspot.com. This rig is so old-timey I wonder how many boats there are in the world like it.

    Hoping to have it inspected, titled and registered in the coming week. I will then report on how it sails, fingers crossed. The masts are slender and bend a lot. The mast design software says they should be safe for inshore cruising but we'll find out!
     

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