Skin-on-frame canoe/kayak plan help

Discussion in 'Boat Design' started by Ruming Jiang, Mar 8, 2021.

  1. portacruise
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    portacruise Senior Member

    From RJ, #40,

     
  2. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Rumars,

    Your comments about SOF fabric is completely wrong.
    I have never put a seam in a kayak hull, it has always been one piece of cloth for the hull.
    Polyester fabric (un heat treated) stretches in any direction you pull but is limited in 2 directions at once.
    Then you heat shrink it.

    Its not good for you to give a description that is not true to someone starting out.
     
  3. Ruming Jiang
    Joined: Mar 2021
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    Location: Vancouver BC Canada

    Ruming Jiang Junior Member

    Wow, really another eye-opener. I'm not a big fan of getting feet wet but the weight is quite impressive.
     
  4. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Upchurchmr please be so kind an reread what I wrote. I specifically mentioned that fabric strech depends on the coating. You are not building with precoated fabric, you use raw of the mill fabric, strech and heat shrink it, then apply the coating, after wich the fabric shape is locked. While I believe you when you say you never put a seam on the hull, I can assure you that most people sew or staple the stem and stern shut when they build your way.

    I am pretty sure you don't build folders, otherwise you would know that they are normally skinned with precoated fabrics that have little to no strech, and are not heat shrinkable. To build a folder with raw fabric one has to use a coating that remains truly flexible forever, aka liquid rubber. It has been done, but nobody has yet found a good formulation that gives acceptable performance, and this method remains experimental. If you know of a product that has reasonable UV and abrasion resistance, forms a nice smooth skin when brushed on, and remains flexible enough to permit repeated folding of the skin for transport, I would be very much obliged if you shared its name with me.

    You also probably missed my statement that rigid SOF boats can be lighter then folders because of the way they are buildt.
     
  5. mitchgrunes
    Joined: Jul 2020
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    mitchgrunes Junior Member

    WARNING: I am not an experienced builder, or an expert in any of this.

    If you are going fairly slow, a boat as long as you want isn't optimal. If you make the entire length of the boat be at waterline, the boat doesn't need to be all that long - in fact it shouldn't be. See:

    Are Longer Kayaks Really Faster? | Guillemot Kayaks https://www.guillemot-kayaks.com/sea-kayak-recreational-kayak/petrel-play-petrel/are-longer-kayaks-really-faster?fbclid=IwAR2_2IYYTFuNvpSi4p0I4QVclTaaorowdczF8Mofk10dj9B9-S4hBY4UJtg

    The length you specify is probably too long to be optimal for whitewater play , by modern standards. Maneuverability is much more fun, and it is probably a good idea to make sure you can reach with your paddle past the front and rear of your boat, so you can pry yourself off of rocks. For safety, two people in separate boats are better, because you can do rescues - and that is just as true in flat and open water as for whitewater. In fact, larger groups of people, some well trained in rescue, are best. You also probably want a flat bottom, "planing hull*" playboat, so you can surf the waves. Such small boats can be close to your desired weight range, but will be much sturdier. I bought an out of date one used for $50. 25 pounds?? The paddle and other gear were more expensive.

    You may wish to consider different boats for whitewater, and for flat water and/or open water, depending on where you plan to live and play. Hang them from your walls. Or leave them on top of or inside of your car(s) if your wife has one too, though you may need to take them out for car repairs.

    There are boats almost as light as you talk about, in roughly the right size range. Most are race boats - reduced durability, but have been taken into class 2 whitewater - even more, by experts, who were willing to take risks. I'm not an expert paddler, but I used a couple 4 meter race boats for years, one of them for decades, almost every day after work, in class 2 and low class 3 whitewater. Both were in the 25 - 30 pound range, but they were larger than they needed to be, for me. They were not as safe in whitewater as modern plastic boats, and I avoided fast rocky locations, though I knew people who took similar boats into class 4, maybe even class 5 water. But one big rock hit could have destroyed them, and left the paddler in an untenable situation in the water. Also, whitewater boats do not handle well for extended periods in open water beam chop - I once got sea sick in a slalom boat on the Chesapeake Bay. Better to use a flat or open water boat designed for that.

    People sometimes sell the old 4 meter slalom race kayaks pretty cheap, including the price range you are talking about, though most are single person boats, and most are kayaks rather than canoes - even the "canoes" are closed deck. Some are fairly sturdy, as long as they don't hit something hard and fast. I think they were required to be a little over 20 pounds to meet specs - but you could certainly use a boat cart to transport them. But if you must buy or build new, we are talking about carbon cloth/kevlar cloth/vacuum bagged epoxy resin, possibly foam core. They aren't cheap or easy to make.

    Many people have cut kayak - and probably canoe - hulls, into 2 or 3 and added screw-together bulkheads. The pieces can be under 20 pounds, and could easily be carried individually, but the total would almost certainly be over. The results could fit into a small car with a liftback, and have also been shipped by air. The previous poster showed a picture of a boat designed that way in the first place.

    BTW I love light weight boats. They are a real joy to handle, especially if they are low enough to the water not to get blown all over the place. They often seem to move almost effortlessly, and, properly designed, they float over the waves instead of bouncing through them. E.g., I took a 30 pound 19"x19' SOF sea kayak into 6.5' wind waves, partially breaking waves, (under controlled near shore cove conditions, that I was fairly certain I could swim out of if I had to), and was astonished at how easy it was to handle in those conditions. It did exactly what I wanted it to, responding immediately to my paddle strokes (done, of course, at the top of waves), whereas my slightly less long but heavier (42 pound) and wider Current Designs Caribou fiberglass boat would have been bouncing all over the place. Since that is substantially longer and possible wider than you probably need, and did not use any fancy materials, just wood, urethane coated nylon, and something like nylon string (I didn't make it myself) I don't doubt that 22 or 23 pounds would be achievable - though maybe not as a folder, and maybe not cheap.

    And BTW, Dyson's website is

    A Builder's Journal • Dyson, Baidarka, and Company http://gdyson.com/a-builders-journal/

    He has also published at least one book on traditionally baidarka - arctic open canoes, though he sometimes calls them kayaks, which some would say should be reserved for "closed deck" boats.

    But, after looking at it, I came to the conclusion that his now-advocated construction techniques require a number of specialized tools, e.g., to bend the aluminum tubing, which will increase your costs. He was looking to create extremely lightweight craft using aerospace age materials.

    Some cars are lower than others. Lifting a heavy boat on top of a high vehicle is hard, but not all vehicles are high. My Venza - a station wagon, maybe too long for you, and the windows offer lousy visibility - has a roof height of about 66", a little more with roof racks, and fits in parking garages without difficulty, yet has good ground clearance, AWD, and lots of space for small boats (or car camping) in the back. Insert a steel pole out to the sides of the front roof rack tube, pull the kayak on a cart up to it, and you could lift one end of the kayak onto the pole, then shift it onto the front rack. Then lift the other end of the boat onto the rear rack, and you need never lift more than half the weight of the boat. I've never owned an 80 pound boat (OK, I once had a plastic 2 person canoe, and hated it), but something somewhat lighter wouldn't be that hard to lift using the cart and the trick I just described. Even easier if it were a two piece boat, and you only had to put it in the back. I think a van or RV could have a lot more space inside, and carry something bigger.

    All and all, I suggest you re-evaluate your needs. Look at different ways of carrying and storing the boat, so weight and packability isn't that high a priority. Decide whether you really need just one boat.

    *"Planing hull" doesn't mean the same thing to everyone. To the ship designers in these forums it means a hydrofoil hull that comes completely out of the water - as with the Flyak, leaving only a thin lifting wing in the water - actually requiring more power from the paddler than human powered aircraft. Materials and design have come a long way since Da Vinci, but humans still have a pretty low power/weight ratio, so hydrofoil use is only possible over a few hundred meters, even for elite young athletes. But to people in the whitewater and surfboat play communities, a planing hull is a relatively flat-bottom hull that develops some lift as it moves through the water by pushing the water down, and consequently turns best if you lean INTO the turn (highly desirable in whitewater). Whereas displacement hulls, which is probably what you want on flatwater or open water, because they are faster or require less effort over long distances at normal human power levels, push water out to the sides, then pull it in again, sink deeper as the move, and typically turn best if leaned OUT OF the turn. (Slalom race boats, Downriver boats, and I think most Creek boats, are mostly displacement hulls, for speed, but require considerable skill, and don't "play" with waves as easily.)
     
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  6. BlueBell
    Joined: May 2017
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    BlueBell "Whatever..."

    RJ,

    Find a plan that is well regarded (has numerous successful builds and sea-trial reports)
    and does what you need it to do (meets your SOR).
    Buy them and build it (or them).
    Take lots of pictures of the build(s) and post them here.
    Then take good quality video of it/them in action and post it here.
    Best of luck.

    BB
     
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  7. mitchgrunes
    Joined: Jul 2020
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    mitchgrunes Junior Member

    Oh - I'm sorry - I see you have already selected your vehicle, so my remarks on that are irrelevant - but it is still true that poles and carts can make rooftop boats more practical, because you only lift half at once.

    It is hard to plan for 30 years in the future. Better, stronger, lighter materials and building techniques may be available, completely outdating anything we consider now. E.g., maybe Dyson's aluminum/plastic designs will be modified to a packable tent-like folder that doubles as a camping tent. Maybe some form of neo-carbon-fiber-poles, or some kind of mono-molecular skin material, will be much stronger and lighter than anything we have now. Use a lightweight inflatable bladder to stiffen it, and you might have exactly what you want. Or maybe the strongest, lightest materials will come down in price. Maybe YOU will design it.

    An incredibly lightweight energy source or battery type may convince you that you don't need to power the boat entirely by yourself - much as some people are moving to battery assisted bicycles and scooters. If cold fusion had worked we might be there now. A cheap abundant energy source might reduce the cost of the lightest, strongest engineered materials.

    For that matter, whether stiffer is always faster is at least a little up for debate. Right now the fastest human powered kayaks and canoes are all fairly stiff. But it is possible that under some wave conditions, a boat that conforms to the waves might not have to fight them as much. The fastest sea creatures are flexible - though they use their muscle-driven flexibility for propulsion, so that doesn't count, unless we find an efficient way to transfer human muscle power to fish-like movements. (Wouldn't that be cool? You move in normal ways, the hull distorts in wave-like motions to push the water along, just like most fish. That which constitutes an efficient boat shape could change significantly, because you would want to maximize wetted surface and interaction with the waves that drive you, instead of minimize them. :) )

    You may decide you want to live somewhere else, which may constrain what types of boating are possible, how big the waves are, how many rocks there are, etc. E.g., a surprising number of one-time whitewater boaters near have moved to fair weather sea kayaking. The types of boat that are ideal for that are substantially different from those that are fun in whitewater, though there is some overlap.

    You and/or your spouse may have health problems that constrain paddling as well.

    You may live in a retirement community, which disallows boats of any type, or has no space for cars or boats.

    We may gain synthetic bodies, that remain forever young.

    Global warming, and/or Antarctic melting, may flood your planned retirement home, or we may run out of land-space because of a flood of forever young retirees, and send most of us into a maritime existence.

    Anyway, science fiction aside, I suggest you design and build or buy for now, rather than the distant future.
     
  8. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    One fairly comfortable solution to wet feet, is stocking foot featherweight breathable waders. Alternatively, wearing ventilated, quick drain and quick dry shoes like crocks produces dry feet in a few minutes each time they are placed atop an out of water crossbar or stirrups. Either might be more preferable to marinating feet in a puddle of muddy water or repeatedly sponging out, while sitting in a canoe shape. There is a a smaller version of the same 8' boat which is the 6' aircraft float tube and wt. around 3.5 pounds....

    Here's one of the lightest rigid boats I have seen, but they may have gone out of business in the last year or so?

    Aquacruisers Poke Boat | Ultra-Lightweight 12-Foot Sit-in Kayak, 18lbs | Cheap Kayaks https://cheapkayaks.net/aquacruisers-poke-boat-ultra-lightweight-12-foot-sit-in-kayak-18lbs/
     
    Last edited: Mar 11, 2021
  9. Ruming Jiang
    Joined: Mar 2021
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    Ruming Jiang Junior Member

    Found the conditions it should meet: The skin can only curve in one direction at a time. It doesn't have to be chined, although it helps with my origami.

    Anyone can help put this into a canoe design? Thanks

    paper hull.jpg paper hull2.jpg
     
  10. Ruming Jiang
    Joined: Mar 2021
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    Location: Vancouver BC Canada

    Ruming Jiang Junior Member

    That's where takedown comes into play.
     
  11. Ruming Jiang
    Joined: Mar 2021
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    Location: Vancouver BC Canada

    Ruming Jiang Junior Member

    Thanks BB. I didn't find anything good enough so far. It probably doesn't exist. Learned a lot from the thread here. Will come back with pictures and video.
     
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  12. Ruming Jiang
    Joined: Mar 2021
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    Location: Vancouver BC Canada

    Ruming Jiang Junior Member

    It hurts. [crying]
    cheap.JPG
     
  13. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Re #54.
    Paper is not like fabric or many other plastics.
    Fabric certainly can bend in two directions at once.

    Have you ever even seen a SOF in person?
     
  14. Tiny Turnip
    Joined: Mar 2008
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    Tiny Turnip Senior Member


    If you are now considering a folding boat, I suggest studying the oru kayak set up videos closely for inspiration. (the coroplast polypropylene is rated at 20,000 fold cycles, btw, and I'll guarantee you'll not be taking it out that many times ;) )

    https://www.youtube.com/results?search_query=oru kayak setup

    Making paper models is exactly the right way to explore the method.

    Also, for general discussion, materials and technique, not necessarily actual designs, try Christine De Merchant Corrugated platic such as coroplast, corplast, plaskolite are used for lightweight boat building, bike cowlings and model airplanes https://www.christinedemerchant.com/corrugated-plastic-coroplast.html

    Boat Designs made from Coroplast and corrugated plastic sheets https://www.christinedemerchant.com/boat-styles-coroplast.html

    who also has a great deal of material on take apart and ultralightweight boats. Take Apart boats save space and are easy to transport https://christinedemerchant.com/boat-styles-take-apart.html

    Ultra Light Boats https://christinedemerchant.com/boat-styles-ultra-light.html

    Paul Elkins is also worth a look: Coro Kayak | Elkinsdiy https://elkinsdiy.com/coro-kayak/

    Coroplast is pretty cheap, pretty light and pretty tough.
     

  15. mitchgrunes
    Joined: Jul 2020
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    mitchgrunes Junior Member

    It depends a lot where you go in your retirement years. :)

    Pool floats:

    www.usatoday.com/story/tech/reviewedcom/2020/05/21/15-best-pool-floats-summer-2020-funboy-sunnylife-ban-do-and-more/111832370

    www.funboy.com/collections/inflatable-pool-floats

    With a little work, you could figure out how to make your own, by sewing and or melting together plastic sheeting. (Many people fabricate their own flotation air bags - I assume the techniques are similar.) Add your own artwork.

    Many surfboards and body boards and sailboards would easily fit in the back of your car, and are also easy to lift on top of your car. I've seen an inflatable stand-up paddleboard. It was inflated tightly enough to actually work on the finger lakes, and looked rather cool. I think it had an adapter kit for sailing too.

    It's actually pretty easy to make a junky boat.

    How about this: take 2 ($1-$2) pool noodles (some have 200-300 lbs flotation each, so you don't need more). Place a rigid plastic or waterproof-coated plywood sheet on top. If you want to get fancy, contour it with bumps for your rear end(s), like a surf ski (or cop out and use seats from old toys - ugly!), and or have a flat area to use it as a stand-up paddleboard, and maybe a pole mount for a sail mast. Lash together into a catamaran with rope. (Or use a cheap foam surfboard instead of pool noodles, and forget the lashing together.) Maybe you could do it for under $100, and the pieces, and maybe even the assembled version, could be very light and be very, very fast to fabricate. But forget whitewater and surf - I assume you will live near a lake or pond.

    For that matter, look up

    DIY kayak

    or

    DIY kayak folding

    on youtube. You will find lots of easy to fabricate examples, some of them light. E.g.,

    www.youtube.com/watch?v=mYqiFbz4tFQ

    www.youtube.com/watch?v=kvA-0DXq2Qs (a folder/break apart boat, that would probably meet all your criteria except whitewater)

    Another cheap easy to build folder, this one on folded plastic and zip ties - you would probably want one longer, and add seat cushions for two.

    www.youtube.com/watch?v=KH08YQet1Fo

    Similar:

    www.youtube.com/watch?v=KH08YQet1Fo

    www.youtube.com/watch?v=3VcTRHdDFPc

    www.youtube.com/watch?v=FihMcHTKo9Q

    and so on.

    And there are lots of boats put together from PVC tubing. Some close off the PVC for flotation. I'm not sure if there is a way to put together PVC that you can take apart again.

    So yes. You can make something crude that floats, you can pack it into or onto your car, and the pieces can be light. But there is no point. With all these boats, something fundamental is missing.

    A boat should be a work of art. It should look and FEEL right, and flow almost silently through the water. Play with it. Lean with it, into turns. Turn around on a stroke or two or three. Push an edge underwater, and make it stand on end. Move it, turn it, maybe roll it, with your hands alone. Touch the water lightly, and feel yourself move. Feel the water and waves and currents interacting with you and your paddle in subtle ways. Along with the well designed boat boat, get or make a lightweight paddle. Used right, a simple Greenland stick will work as well as anything fancier, unless you need very fast acceleration, and lets you play around in ways no European paddle ever will.

    A cheaply built ugly boat, ultra-light or not, compact or not, that can move if you really work at it, simply isn't the point. You may as well go to a gym, or lift weights.

    If you have an 80 pound open canoe, you are already missing that. Hardly anyone uses big open canoes anymore. There is no way to make that fun. It's the equivalent of a moving van, barge, or garbage scow. Lots of exercise, and can carry a family, or haul out trash, but it cannot create joy.

    Go to a boat store, and try some lightweight well shaped boats out. Or borrow from friends. Experience the joy of beautifully made craft.
     
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