need help in building a small catamaran

Discussion in 'Multihulls' started by yoram, Nov 18, 2010.

  1. yoram
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    yoram Senior Member

    thanks again, Manfred

    the design you have sent me is really very much like the one i want to build. i might do it. i want to get some experience in building a very simple and cheap canoe and then to see if i like the building process. if i do, then i would try something a bit bigger, like i wanted in the first place. so the plans you have sent me are good and simple and fit my needs. i am just a bit apprihensive about having the side of the canoe so low. 30.5 cm! and the canoe is open. even very low waves would fill it up with water, isn't it? i have no experience with it. beside extra weight, what are the disadvanteges of 40 cm side walls?
     
  2. yoram
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    yoram Senior Member

    do you have a photo of this canoe (cheap canoe from eboat.com) so i could see how it looks like?
     
  3. Manfred.pech
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    Manfred.pech Senior Member

    Fotos

    Yoram, when you look back, you will find fotos here from a similiar canoe: http://www.duckworksmagazine.com/02/projects/knudsen/index.htm

    If you want a somewhat more advanced but simple design, which has been used for multihulls already please look for the designs of Jim Michalak: http://www.duckworksbbs.com/plans/jim/larsboat/index.htm

    http://www.duckworksbbs.com/plans/jim/gizmo/index.htm

    http://www.duckworksbbs.com/plans/jim/trilars/index.htm

    Cheap Canoe is here:
    eboat.net.jpg
     
  4. michael pierzga
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    michael pierzga Senior Member

    Great thing about flat bottoms is they are simple, fast and cheap to build. Why not go to the model aircraft shop, pick up some thin modeling wood, superglue, a razor knife and begin to desgn your own ? Use the general plans from a site like duckworks to get you on the right path, then experiment with the size shape you need. Well its a little scale model it becomes easy to visualize how it will be built and how shear and rocker affect the looks.
     
  5. yoram
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    yoram Senior Member

    yes i remember this canoe from Denmark, the one that makes a catamaran when another canoe is join to it. it doesn't look much like the cheap canoe. it has also a deck. i am still thinking strongly to build the cheap canoe since it is very simple and would give me the practice of working with the stitch and glue system. btw, when the stitches are connecting the pannels, how do you applay the putty? don"t the stitches get in the way? and the same for the fiberglass tape, how can you put the tape when the stitches are in the way?
     
  6. michael pierzga
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    michael pierzga Senior Member

    Oh... the stitches pull the shape of the ply into a boat. then yopu use little blobs of epoxy to glue the plywood edges of the panel together....then remove the stitches, then fibreglass tape the seam. All you need is a little epoxy glue to hold the shape after the stitches are pulled
     
  7. yoram
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    yoram Senior Member

    thanks, i did it with some kind of material which is between paper and wood (do not know how it is called in english, like hardened cardboard) and made already two models of canoes and taped it with duct tape. i even put a manikan of the same scale to see how it looks. but these were canoe i have design which were design after examening all kind of other canoes. but i do think that taking already well proven design would be milion times better. Manfred send me the link to a very simple canoe plans and i think i would go with that.
     
  8. Manfred.pech
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    Manfred.pech Senior Member

    Model

    This is a good and helpful method. When you have a somewhat bigger model you can make tow tests (1:5, 1:3) at the waterside or in the harbour and you will find out what is really the best for you.
     
  9. yoram
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    yoram Senior Member

    but isn't the stiches disturbing in the way of glueing the lines where the boards are connecting, meeting? you have them every 15 cm along this line so do you push the epoxy putty under them into the connection?
     
  10. michael pierzga
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    michael pierzga Senior Member

    Best when working with a plywood design to use a stiff model material. Plywood cant compound bend. If you used a soft flexable material for your model you might design a compound bend into it that would be impossible to build with a sheet of plywood. Stiff cardboard works Ok for models. thin sheet metal is also good, same with the superthin modeling ply you can by at a model shop. Thin paper would be no good.
     
  11. michael pierzga
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    michael pierzga Senior Member

    The little blobs of epoxy would be similar to Tack welding a piece of steel. only a few little tack welds of expoxy needed to hold the panels in shape. Very few .. If you used a stitch every 20cm then a tack weld of epoxy every 20cm, between each stitch, would hold everything together fine.

    It will all become obvious well you make you scale model with superglue and thin wood
     
  12. yoram
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    yoram Senior Member

    no it is as hard as ply and i cut it with jigsaw. scale 1:5 and the second on was 1:6. it looks ugly because i connected the parts with gray duct tape but it gives an idea about how it should look. i could cover it all with duct tape and try it in the bath... the lake near by is frozen.
     
  13. yoram
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    yoram Senior Member

    Michael, i do not understand. i read on the net and see in youtube how they do this putty from epoxy and sawdust or other form of powder that becomes like peanut butter and they applay it along all the line where the 2 boards meet. so i do not have to do that only to applay it in between the stitches for bits of 20cm and then break for 0.5 cm for the stitch and then another 20cm epoxy putty and then break and so on? the idea is to keep it together in shape until i turn it up side down and put the glass tape on?
     
  14. yoram
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    yoram Senior Member

    Manfred, i got the photos of the canoe now. thanks. looks good and promissing.
     

  15. michael pierzga
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    michael pierzga Senior Member

    Well certainly you would apply the epoxy peanut butter to as much visable space between stitches as possible. Sooner or later you must fill the entire seam... 100 percent with epoxy peanut butter ...and build a raduised fillet to put your glass over. Sometimes its easier to use mini spot welds...remove the stitching then give the whole seam a smooth fill of epoxy. Depends on the shape of your boat.... many times complex shapes need many stitches to pull the ply in and some shapes need only a few.

    Many good acticles on the net concerning this construction as well as blogs of home builders actually doing it before your eyes and passing on secrets like a wooden dowel inside the joint and under a stitch to pull the ply even.
     
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