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Cash prize of 250 GBP - Dinghy Design Competition

  • 01 Apr 2022 11:58
    Reply # 12689886 on 10211344
    Anonymous member (Administrator)

    Graeme wrote: I still think ply is better than fibreglass for a dingy, Arne.»

    I don’t disagree, for sure. In addition to being lighter, they are also easier (or more inviting) to be modified or customised. It is super easy to increase or reduce the beam of the pram type plywood dinghies, to suit the needed carrying capacity. As shown earlier, I now aim on fitting enough frames (elbows) to secure the shape of the boat without structural thwarts, and thus be free to fit whatever interior one fancies.

    Arne


  • 01 Apr 2022 10:54
    Reply # 12689829 on 10211344

    Perhaps Arne had in mind the rotomoulded and vacuum formed dinghies (eg Sportyak) and sit-on kayaks - that is how to mass produce a robust knockabout boat. But they are all heavier than GRP, which is heavier than plywood.

    CNC cutting is the way for cash-rich but time-poor folks to build a plywood boat. And I suspect that many of the clients of the likes of Jordan Boats, Fyne Boats and other kit boat suppliers are first time builders who are not confident enough that their lofting and cutting abilities are up to the task.

    Last modified: 01 Apr 2022 10:58 | Anonymous member
  • 01 Apr 2022 10:12
    Reply # 12689826 on 10211344
    Anonymous member (Administrator)

    Arne wrote: "However, no method beats plastic when it comes to stamping out dinghies, these days."

    I still think ply is bettere than fibreglass for a dingy, Arne. For "stamping out" perhaps fibreglass suits production better, but not for using. A good dinghy is a light dinghy. Plywood dinghies can be and should be light.

    Any fibreglass dinghy I have had (and I still have one that the grand kids fool around in occasionally) has been nice and durable, but too heavy to be convenient.


    Last modified: 01 Apr 2022 10:23 | Anonymous member (Administrator)
  • 01 Apr 2022 09:55
    Reply # 12689824 on 10211344
    Anonymous member (Administrator)

    Something in between CNC-age and stone-age...

    I think it was unfortunate that the competition was started without a firmer set of specifications.

    Still, from those loose specs it did not appear that the design was to be optimised for mass production. Computer-designs resulting in dxf-files for a plotter or CNC-cutter is fine if one wants to sell kits. For one-offs, I felt it was better to take one step back in technology. My designs were meant to let someone follow a few sheets of building plans without needing computer tools or skills.

    Still, my designs like Halibut and Medium Boy, are actually sitting in dxf-format in my computer. If I had a CNC-cutter shop available nearby, I could easily show up there with a memory stick in hand and have most of the planks cut out for me. That would ensure accuracy and save heaps of time. (..I guess I would just have the planks cut out from thin, cheap plywood and use them as patterns so I could build another few dinghies on demand...).

    I have just borrowed a biography about E.G. van de Stadt. He produced a great number of plywood designs in the forties and well into the sixties, both for professional building and for homebuilders. Even kits. However, no method beats plastic when it comes to stamping out dinghies, these days. Plywood is, with few exceptions for the home-builders.

    Arne


    Last modified: 01 Apr 2022 09:57 | Anonymous member (Administrator)
  • 01 Apr 2022 08:50
    Reply # 12689771 on 10211344

    Would have been interesting if there had been a stipulation that the tender had to be built on a beach with only hand tools that were carried on the mothership (I know of one such case). Different designs would have resulted.

    Would have been interesting if [insert theoretical stipulation here]...

    But there were no such stipulations. Only loose guidance.

    How far back would you like to wind the clock, Jan? Is pre-21st century far enough, so as to preclude modern, fast, efficient ply boatbuilding methods? Or must we go back to pre-20th century methods, and fell trees and cut and shape planks with axe, handsaw and adze? 

  • 31 Mar 2022 21:35
    Reply # 12689237 on 10211344

    Would have been interesting if the first stipulation of the dinghy design competition was that the design had to be presentable as a table of offsets. 

  • 31 Mar 2022 11:06
    Reply # 12688405 on 10211344
    Anonymous

    Thank You very much, these pdfs are perfect an in the meantime I found out that the company where I bought my first class Okoume marine plywood sheets can cut them with your DXF files. I am just waiting how much that will cost before I have it done and save myself a lot of plotting by hand.

  • 31 Mar 2022 09:45
    Reply # 12688361 on 10211344

    Yes, it's tedious to dimension something as intricate as this, which is why I don't want to do it! If I built one, the first step would be simply giving the DXF file to a CNC company such as Jordan Boats, in the UK.

    I'll see what I can do to provide PDF files that will help you. JPG files aren't much use, as they aren't really to scale.

    Try these PDFs of the ply panels at 1:5 scale

    https://app.box.com/s/tl3oy9wag6l0rkj5p1zpcmp9s5p6efbu

    3 files
    Last modified: 31 Mar 2022 10:16 | Anonymous member
  • 31 Mar 2022 09:16
    Reply # 12688339 on 10211344
    Anonymous

    Hi David, Quite easy to make your tender to Sibling with the slots provided to put it together. I do have LibreCAD on my PC but I am hopeless in using it. Is there an easy way to find out the dimensions from the dxf files ? I tried with the dimension tool from one point to another but this is tedious. Earlier on you uploaded besides the dxf files also JPG and PDF formats of the three plywood panels which I could easily print on my A4 printer. I wonder if I have some scale of a nested panel ( 250 x 125 cm ) it should fit onto 6 A4 pages in poster mode printing. I am keen on getting the dimensions which I then could plot by hand onto the plywood panels. Maybe You can give me some hints.

  • 30 Mar 2022 19:49
    Reply # 12687509 on 12672539
    I wrote:

    Karl, I should say that I never completed the details on these drawings, just the basic shapes. There will at least need to be slots added so that the longitudinals and athwartships components will engage with each other. If anyone makes a positive commitment to build, for sure, I'd be happy to do some more work; but really, this is a "sketch of a design", as it stands now. 

    Well, having no other projects on the go, I've spent some time adding the detailing that is needed to build a full-size boat:

    https://app.box.com/s/1vb1yasdmpfqlx7x4iqc9k5g1fjfnw85

    It should be fairly quick and easy to slot it together. 

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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