paddleboard and kayak teardrop shape

Discussion in 'Boat Design' started by Alwaysthinking., Sep 5, 2019.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    Ah, a wise old head !
     
  2. Alwaysthinking.
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    Alwaysthinking. Junior Member

    Here's another way of looking at it.
    White water kayaks and canoes have blunt ends with rockered keels.
    Touring kayaks and canoes have pointed ends and straight keels.
    If you cut the first couple feet off the touring boat and replaced it with the first couple feet of the whitewater boat, you'd have something close to what I'm thinking about.
    I've spent many, many, many hours in canoes. If you've not spent much time in a canoe, you might not know that they don't like to go straight. Being long and narrow, you'd think they would but they don't. You are constantly battling to keep them going straight. Loading them a little stern heavy helps, but they still want to turn. I won't go into the relative effect of bow and stern paddlers. If you get up a good head of steam and then stop paddling, a canoe will go straight for a few seconds, then start to turn. Slowly at first, then more sharply.
    This is messed up. A boat that would go straight when you wanted it to, but turn easily when you needed it to, would save a lot of energy and frustration. I'm hoping my design would help. There are already canoes and kayaks with subtle hints of my idea, but I want to take it a couple steps farther.
     
  3. gonzo
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    gonzo Senior Member

    I think you may have been on badly designed canoes that won't go straight. I can paddle a good canoe alone without it turning out of control.
     
  4. portacruise
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    portacruise Senior Member

    How about an inflatable kayak that can change its shape as you add or remove air with a mouth tube? That way you could have the best of both worlds.
     
  5. Squidly-Diddly
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    Squidly-Diddly Senior Member

    my fave thing about my old Aquaterra Prism SOT was that I could sit up on deck directly behind the seat OR get up on my knees (that put weight a bit forward but still OK on flat water) to work diff parts of body.

    I hear one of the big problems/issues with paddle-boards is y0u are stuck in that rather athletic pose, and can't use the vessel for more relaxed configs.

    So you might be on to something.
     
  6. Alwaysthinking.
    Joined: Sep 2019
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    Alwaysthinking. Junior Member

    I knew someone was going to say something like this. I can keep a boat going straight too, but not without using J-strokes, ruddering, or switching sides frequently. A canoe doesn't want to go straight. Any canoe. I have a We-no-nah, a Mad River, and a Swift. I've owned Daggers and Old Towns. They all want to turn. Stop paddling and they quickly start turning on their own.
     
  7. Alwaysthinking.
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    Alwaysthinking. Junior Member

    I downloaded Shape 3D, a surfboard design program. I'm not sure it will let me do the things I want to and it'll take me a while to get it figured out. I'm not that computer savvy. Or maybe I'm just not terribly bright:(. Either way, it might take me a while to come up with a drawing, then it may not be possible for me to post the file on here. I'm working on getting another program, one I'm more familiar with, installed on this computer. I'm hoping I don't have to pay for it a second time.
    After I get a CAD drawing, there are companies that will mill out the design in foam. I then just have to cover it in glass.
     
  8. Heimfried
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    Heimfried Senior Member

    This is a very likeable approach to me and I wish you luck.
     
  9. Alwaysthinking.
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    Alwaysthinking. Junior Member

    I was thinking (there I go again). Regarding the original America's Cup race. I think the British boat has gotten a bad rap Most likely the American boat was faster. And most likely the "fish" shape of the British boat had something to do with it. But the British must have thought it was a fast boat or wouldn't have entered it. I doubt if they said "This things a slug, but let's enter it anyway because it's shaped like a fish." I think it would be a huge oversimplification to say that the American's won solely because the British boat was shaped like a fish. You could put me in the fastest sailboat on the planet and most of the people reading this could beat me with a garbage scow. I doubt that the fish form of the British boat was the only factor in their loss. Might not have even played a major role.
     
  10. gonzo
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    gonzo Senior Member

    The story of the America's win is easy to find online. There was some element of luck with one of the faster boats getting damage. However, the America was a radically different design from the plank on frame British yachts. Depending on weather conditions, one is faster than the other.
     
  11. Dolfiman
    Joined: Aug 2017
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    Dolfiman Senior Member

    I like the spirit of your approach, Amateur has the privilege to think different and to experiment out of the box, which is a lot less easy for Professional who should deliver within the current state of the art. Yet, take care of your savings for a long happy retirement. Attached my quick and dirty tentative illustration of your starting ideas ;)
     

    Attached Files:

  12. upchurchmr
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    upchurchmr Senior Member

    One thing to think about is that neither subs or aircraft (thinking subsonic commercial planes) are actually tear drop shaped.
    Both have a significant portion of the length which is a constant thickness.
    Meaning they have a bulb (sort of) shaped bow, a long tube, and then a tapered stern.

    Please also look at pictures of a submarine on the surface. It has a huge bow wake, possibly 3x the width of the sub. Subs are terrible for drag on the surface.
    The shape has been designed to be best below the surface, and not when close to the surface.

    Good luck with your development. A kayak or paddleboard is relatively cheap for experimenting.
    Please come back and show us what you get. Many posters with "new" ideas simply disappear from the thread.
    When I was trying to build a short rowing catamaran, it took 3 iterations to get something that actually worked OK, but did not beat anything I was comparing against.

    Please also think of what experiment will show your benefits against current versions.
     
  13. Alwaysthinking.
    Joined: Sep 2019
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    Alwaysthinking. Junior Member

    Shape 3D tutorials.
    Shape3d : Surfboard Design Software http://shape3d.com/Support/VideoTutorials.aspx
    Looks like Shape 3D has some good tutorials. Unfortunately, the guy has a thick French accent and goes pretty fast.
    I got the free download. I might have to pay for the full version to be able to do what I want, but I think it will let me do it and maybe faster than it would on a boat CAD program rather than a surfboard specific one. It is obviously intended for making surf skis and stand-up paddle boards etc.
    I've played with CAD boat designs quite a bit and my thinking is often shaped by the process. Do you guys find that to be true too?
    So, what I had in mind originally, might end up quite different. I'm already leaning toward something that looks more like a surfboard or paddleboard and less like a kayak. If I end up with a design that looks like something I can order, pre-made, online, that's probably what I'll do.
     
  14. Alwaysthinking.
    Joined: Sep 2019
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    Alwaysthinking. Junior Member

    Yes, I'm aware of all that. I'm considering two additional things. One is that a submarine is hugely heavy for it's size, meaning it doesn't actually float on the surface the way a glass covered foam core sit-on-top kayak would. Second, I'm going to try and keep the center of buoyancy aft by rockering the front of the boat and keeping a flat keel aft. I think most of you are picturing something far different from what I'm picturing in my head.
    If I had more money and was less afraid of putting my body through more exposure to epoxy and sanded fiberglass, I would probably make two boats, one with a pointed bow and one with a blunt bow and compare the two. I've considered trying to make a test tank and models, but that probably won't happen.
     

  15. Alwaysthinking.
    Joined: Sep 2019
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    Alwaysthinking. Junior Member

    Something I'm also considering and will learn more as I actually go through the design process, is that, with the rockered bow I'm planning, I may be able to have a very pointed bow, but the shape of the hull where it hits the waterline would be very rounded. Like I said, I think most of you are picturing designs far different from what I have in my head. I'm no genius, just ask my brother who is, but I'm not actually as stupid as I look or sound.
     
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