Small Kayak - Under 13 feet - Stability?

Discussion in 'Stability' started by millionswords, Dec 16, 2008.

  1. ancient kayaker
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    ancient kayaker aka Terry Haines

    Go for it MS: and you will need all those tools, I'm betting. Remember sharp tools use less forces so they are much safer than blunt ones, just in case you are inexperienced at working wood. Also, no reason why you can't have both ply and bamboo frames.

    Messy: I hadn't heard of the yuloh and I thank you for the information. I did a net search and it is an interesting idea; it seems to be optimized for a standing sculler but can be adapted for ue in a coracle/parisal I imagine.
     
  2. millionswords
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    millionswords HomeMade Kayak?

    hi AK,

    I can have both ply and bamboo, but Ply beats my budget.
    When using Ply I need marine ply. Which is expensive and not my kind of budget for the frame at this point. More over, ply makes building work easier, but takes more to get it cut, and drilled etc. Also I want to make it as traditional as possible keeping the challenge involved in it. Just like the Johansen Kayak, I want it to be a replica in my adapted design.

    Once this is done and a success, I would be making two or more boats for friends that has to go company with me. During these building a composite off Ply cross-sections and bamboo will be employed. There is scope for improvement always!

    This project - till frame is done and saran wrap test is over will be a prototype test for me. Once that is done, I might think of investing on ply to make it look better either! Lets see first how things turn out!
     
  3. ShagRock
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    ShagRock Junior Member

    This is a fascinating thread! Bamboo was used extensively in boats and ships particularly in countries in southeast Asia, India, Indonesia and China etc. Extensive sea trade was highly developed in ancient times. paraws, proas come to mind. I don't where I found this photo of the lovely white canoe, but it may be in India??. I believe it is a SOF canoe with Bamboo frames (please correct me if I'm wrong here) - note the black burn chars on the ribs from heat bending. Also, neat use of small blocks as separators to make the lashing easier. For comparison sake, I included its western cousin:)

    Bamboo is poor for nailing, but your ladders were interesting. What if the kayak stern was an triangular piece of wood (or some shape) that had holes drilled in the aft side to receive the ends of bamboo stringers. Glue them tight! Bamboo also has good flotation potential.

    Also, would it make any sense to look at monofilament linefor lashing - it's now being used in some strip-plank boats to avoid dents in the wood from edge-nailing. Real curious to see how you make out!

    Newfie
     

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  4. millionswords
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    millionswords HomeMade Kayak?

    Some updates

    Hi Ak, Alan ans Messabout...

    I dunno if this is the right section to make the updates for the building WIP.
    Any how as this is where we discussed a lot about the kayak, I post here.

    I started to buy tools and hunt for bamboo poles one by one, and collected them over the past few weeks, ad mist other work. I bought a Power Drill and some saw, wax, thread etc etc. When I thought it is all what I needed, I started out to put things together, and here is what I did yesterday afternoon.

    1. cut miters for the poles on the stern side, joined them temporarily with rubber tube strings.
    2. inserted a temporary stringer in the Half-Mark and drilled it to let the string go through, tied it in place with Hemp-String.
    3. now I joined the bow side, again with rubber tubing.

    The bow side has the sleeker side of the Bamboo pole.
    As I searched for bamboo poles, I found either they are grown crooked at the top or at the bottom, and only very few about 50 in 1 grow straight from the bottom to top in a almost straight line. I found some grow like a big curve of about 17 feet tall. I picked one of these thinking they will any way be bent, so the already present bend would help. But seems it proves wrong, because I need the poles to bend evenly.

    More over in yesterday's exercise I learned how a inset infected bamboo would behave and look., partially green, partially yellow and pale in color, partially patchy and very uneven colouration. I worked hard on a pole and it broke after a few minutes of bending and lashing.

    I have to replace the left side pole with a much straighter stern side. Will look for some in the market today or so.

    1 doubt.

    I happen to notice the stern side with the ROOT side of the bamboo would grow more heavy as I build the kayak. What about the weight ratio between the Bow and stern?

    Should i reverse the bamboo direction so as to place 1 root on either side?

    Looking forward, to hear from you guys!

    MS
     

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  5. alan white
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    alan white Senior Member

    Weight difference between bow and stern will not be enough to notice. Please keep up the photos--- it's an interesting project to watch, and no doubt useful to others who will be working with bamboo.
     
  6. robherc
    Joined: Dec 2008
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    robherc Designer/Hobbyist

    I agree with A.W. ... and even if it is noticeable, a slight amount of bow-up trim shouldn't hurt you much (at least not nearly as much as the opposite would).
    Also, I think this is the perfect place for you to post updates. Keeps all the info. on this project organized :)
     
  7. millionswords
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    millionswords HomeMade Kayak?

    Sure will keep updating here!!

    Oh k,

    Weight difference might be very little, as the bamboo dries, it will be least noticeable. But I can balance it with root to tip; root to tip combination, if you people think it is necessary.

    Sure will keep updating the progress here in this thread, this thread has helped me decide on many things while planning, and I owe this to the thread and forum.

    Thanks for the support robherc, welcome aboard to the Bamboo Kayak project!

    Have you guys noticed this little zig-zag bend in the stern side here:
     

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  8. millionswords
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    millionswords HomeMade Kayak?

    Deck Stringers Getting ready...

    Here is the set of Deck Stringers getting ready.
    I might need to attach two bamboo sticks to achieve the knee bend or employ some other method. Any ideas welcome...

    Thygesen made it all look so easy!
    Here is his Knee Bend Stringer in the last picture!

    ----------------------------------

    Update: I went out to get some ply and cut some Jigs out of them so that it can hold better than the rubber tubes.
    It worked just fine, will update with pictures of how it is installed 2morro.

    Now will post the Jigs and how the deck stringers are cut and ready for lashing.
    If time permits, I shall drill holes and lash them tomorrow, and hopefully the deck will be ready by the end of day!

    Here are the pictures from todays work...
     

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    Last edited: Feb 4, 2009
  9. ancient kayaker
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    ancient kayaker aka Terry Haines

    It's nice to see you making progress. I would suggest keeping the root ends together at one end of the boat. There's a trade-off for each end.

    You can put the root ends towards the bow for strength. That would tend to make the stern portion curve more than the bow causing the maximum beam to shift aft, which results in a faster boat.

    However, when carrying kayaks I find the bow always wants to hit the ground because the cockpit is behind the balance point and putting the root ends towards the stern would compensate for that.

    Your choice, I don't think it matters much unless there's a huge differnce between the 2 ends of the bamboo, in which case it might be wiser to splice them to get a more even distribution of stiffness.

    I think you should try out the heating method for bending bamboo, using it to straighten the kinks that some of the pieces seem to have.

    Keep posting pictures as we are all learning from this.
     
  10. millionswords
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    millionswords HomeMade Kayak?

    AK,

    Splitting the bamboo will expose it, and treating it will become mandatory.
    Will Keep this in mind, once some portion of the deck is set up, I will make sure I check if the Bow and Stern are some what balanced, with various methods to compensate it.

    What I have in mind:

    1. Join the root ends, make the Gunwale.
    2. Join the Root ends reverse it and make the stringer portion,
    3. Reverse the root end and lash the Keel

    Which will balance the overall weight.
    As bamboo dries, the weight factor will balance itself to a certain extent which will help me a bit too. So building with Gunwales reversed to the Stringer poles would do the job.

    Will update as I progress..
     
  11. ancient kayaker
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    ancient kayaker aka Terry Haines

    Sounds OK, but I did not mean split I meant splice which is a method of joining 2 lengths of bamboo. I think that a scarf joint would work, that would involve selecting 2 pieces of bamboo to be joined together, cutting the ends at a fine angle, perhaps 1 in 10, and then joining them either with glue (epoxy suggested) or lashing them together. If they are lashed it might be a good idea to ensure they do not work apart, by drilling a hole across the joint and inserting a dowel. However, if the bamboo is long enough you may not need to do that.
     
  12. millionswords
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    millionswords HomeMade Kayak?

    Update Progress...

    Oh, K

    That way eliminating the uneven bamboo issue.
    Well, Will keep that in mind, I'm going ahead with what ever the single bamboo length offers. Dunno how good will a scarf joint work with bamboo, I have seen Wood Scarf joints, that stay goo enough. But Bamboo being fibrous, unlike wood, will give way for peeling over some time.

    Updating now with the progress made this morning, in the past 3 hours.

    1. Cut the rest of the deck stringers.
    2. Drilled holes in them,
    3. Attached the middle deck stringers, with waxed hemp.
    4. Cut the stern end and drilled holes, lashed them with hemp string.

    Todo: attach the rest of the deck stringers, and have a look at the finished deck side frame!
     

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  13. millionswords
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    millionswords HomeMade Kayak?

    Miter of Scarf Joint - what is it?

    Issue1:

    [​IMG]

    If you look at the image above,
    When I try to hold the two miter-cut ends there is enormous elastic strength from the bamboo, and hence i don't get to join them right.

    As compared to what Thygesen has achieved, what I get to see is pathetic. I'm doing it all alone, dunno if that is the reason, will get help from a friend on Saturday, shall update after I do so. Meanwhile, any ideas welcome.
     
  14. ancient kayaker
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    ancient kayaker aka Terry Haines

    Can you fit a dowel into the center hole to help join the two pieces? Also, I can see why a simple scarfed joint doesn't work, you have round elements to join and the scarf joint is intended for flat planks. A scarf joint can bear loads in only one direction and the bamboo has to bear loads in all directions. So you will have to cut the ends straight across. A dowel may not have as much strength of the bamboo. Perhaps the traditional craftsmen have already worked out a method. If not, perhaps a thin sleeve over the joint in addition to the inner dowel will work; it is important to fill all voids with epoxy to ensure that the strain of bending is taken up evenly by the dowel and the sleeve at the same time, or one will bear all the strain and fracture, followed by the other. It would be best if the parts fit well without the glue, so the dry joint has some rigidity, then the glue can be added.
     

  15. millionswords
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    millionswords HomeMade Kayak?

    Hi AK,

    I started to dream about the next project already, a wooden Kayak that is. :)
    I checked with the timber merchants, and found the prices to be alright because I may need just very little timber, for the stringers and the ribs. Some what under $20 I can get red cedar some 80 to 100 feet in total length.

    Guess working with wood will have less complications, and innovations, and will be a very heartening project. Well that is for later, what I did yesterday was to remove the lashings, and do it all again with more strength and perfection. A friend came by to help me out holding and lashing. Upper deck is done, with all deck ribs lashing with waxed hemp string. [spent about 3 hours]

    We will continue today and try to finish the stringers and the hull ribs, need to check is the bamboo poles that I have will be pertinent to the hull stringer. If, it is, we shall complete the lashing of hull stringer, and ribs, and keep the keelson lashing for another day.

    Keelson lashing will need a little bit of innovation so as to achieve a little rocker in the bottom, dunno what challenges await me.

    I was in the meantime, taking serious consideration for your idea of bending ribs AK, but without making drills in the gunwale we cannot keep it tied in shape. If holes are drilled throughout the Gunwale the bamboo would loose the longitudinal strength and will break in the weakest section!!

    Instead of taking the risk, I thought let me continue the building and experiment with this idea at a later time! [what do u think AK?]

    I also started to cut flat strips of bamboo, about 1" in width, but they too need to be inserted into the gunwales with grooves chiseled in them, spoiling the longitudinal strength of bamboo. I some how dropped the idea of bending stringers fearing this, and continue to lash the ribs.
     
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