Guest Joe Nelson Posted December 21, 2002 Report Share Posted December 21, 2002 Anyone else have trouble with their side stringers not being level at the middle of the boat (core sound)? I installed the side bench longitudinal nailers level from the ends of the side stringers (from the fore to the aft bulkheads). I am about 1.5" low at the center of the side panel stringers. Everything on the hull is already glassed, so I am stuck with what I have. I figure that it is a function of the bottom shape and side flair. The natural tendancy of the sides was to flex out and I have a couple inches if extra beam. So I think I have slightly more rocker and more flair to the hull than designed. It may be a little slower but should also be a little more sea worthy as a trade off. I figure on just adding some additional nailers to the hull side panels so that the benches will be level. (fortunately the old stringers will be below and sealed out of sight) But this also complicates the building of the centerboard case (additional height). But I think the centerboard as designed should be fine without modification. The benches will be more comfortable due to the additional 1.5" in height. I built on cradles and in hind sight, I think that building on the floor would have produced a flatter hull. Unless a center mold could be made and oriented vertically (no lines or dimensions provided to make this possible) I think it best to build without a cradle. Any comments? Joe joe_nelson22@hotmail.com Quote Link to comment Share on other sites More sharing options...
Guest Terry Dunn Posted December 22, 2002 Report Share Posted December 22, 2002 I suspect I will have the same problem. My sides are also flexing out. I also built the hull on cradles. I suspect the position of the cradles had more to do with the result than anything. One cradle at the stern and one at the forward bulkhead. I probably should have placed them closer together. Terry terryplay@msn.com Quote Link to comment Share on other sites More sharing options...
Guest Brent Sparsk Posted December 22, 2002 Report Share Posted December 22, 2002 Well, this is indeed interesting. I spent yesterday building the cradle to build my CS20 in. I planned one support just under the forward bulk head, another 2" aft of the temporary support, and a third at the aft bulkhead. But maybe I will reconsider. I am glad this forum is available to share experiences. As I really dont want to do all the stitch work kneeling, I am looking for an improved solution. I am envisioning a two by four support along the keel line running between cradles to keep the boat from 'bananaing'. I might need some small blocks on top of the two by four to deliver the designed in rocker. Thanks for giving us the benefit our your learnings. bljcatsparks@earthlink.net Quote Link to comment Share on other sites More sharing options...
Guest Joe Nelson Posted December 22, 2002 Report Share Posted December 22, 2002 To me, the ultimate solution would be for Graham to provide a dimension relative to the vertical placement of a third cradle at the temporary mid frame. We already have the dimensions of the hull at that point. All you would need is a figure as to how far down to locate it in relation to a level line from the for/aft bulkheads height (such as...locate the fore/aft cradles level with each other and drop the center cradle X"). Then you could snug up the bottom panels right down to the center cradle and know it is perfect. I made my cradles so that the center of the vee is at 24" and that is a great working height most of the time. Joe joe_nelson22@hotmail.com Quote Link to comment Share on other sites More sharing options...
Guest John Burritt Posted December 23, 2002 Report Share Posted December 23, 2002 Look at the profile plan of the boat. The waterline should be shown. Measure the distance down from the waterline to the keel at each point of interest. Use the scale shown to translate that into actual distances. This gives you the relative heights of the different points. Use these to set up your cradles. Joe, just looked at your "stitching party" picture showing the temporary bulkhead in place. How did you get extra beam? Have you installed the inwales yet? If not, they will staighten the sides a bunch (scientific term) and draw them together. Also, if you haven't installed them, do them both at the same time so that the boat isn't pulled out of shape. This is another opportunity to give your buddies some hands-on experience. Interesting problem. jbncb@coastalnet.com Quote Link to comment Share on other sites More sharing options...
Guest Joe Nelson Posted December 23, 2002 Report Share Posted December 23, 2002 Inwales are already installed. Keel batten is also installed. The keel batten helped. I am not worried about my situation. It may be a slight departure from the ideal or designed shape, but I dont think its enough to make a big difference in performance. If it were a class boat that is measured for racing, it could be a problem. But thats one reason you dont see boats like Lightnings without frames. joe_nelson22@hotmail.com Quote Link to comment Share on other sites More sharing options...
Guest Graham Byrnes Posted December 24, 2002 Report Share Posted December 24, 2002 The plan has 1/2" of rocker in the side stringers and you apparently have 1 1/2". Extra flair in the sides will add more rocker to the side stringers. I measured the keel rocker between the bulkheads for the height of a center frame for the cradle and it is 1 7/8" below a straight line stretched between frames set at the fore and aft bulkheads. I don't know if a center frame will solve the problem but it can't hurt. The blue CS20 that you have on your web site has extra rocker, he told me that deliberately induced it by pulling the sides out. It does't seem to hurt speed as he won the last Great Race. Quote Link to comment Share on other sites More sharing options...
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