Pikku-ee, new rowing/sailing dinghy design

Discussion in 'Wooden Boat Building and Restoration' started by jarmo.hakkinen, Aug 18, 2016.

  1. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    This little rowing boat will be made of 6 mm Vendia Marine Plank and Finnish pine, frames and knees of birch plywood. It is still under design process, hopefully we will be able to start building the prototype later this autumn, to have it ready next spring, when the lakes are free of ice.

    As usually, scantlings will be according to ISO-standards, as will flotation too. Boat measures 4,6 x 1,5 x 0,15 meters with two persons on board. All major structural components will be CNC-cut, as will templates for lesser parts, in the wake of the Niko -fitness rowing boat.

    To be modeled before starting the build:
    - frames
    - thwarts
    - rudder and centerboard
    - flotation modules
    - sails and rig
    - and...

    I'll post some pictures and write a few lines every now and then. Here's a link to a short animation: https://www.facebook.com/276355705854620/videos/642442125912641/?pnref=story
     

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    Last edited: Aug 18, 2016
  2. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    Some progress...
     

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  3. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Jarmo; That is a fine looking boat. It is a classical type, not surprisingly from a Scandinavian drawing board.

    Since you specify a 6mm skin, it seems that you may be giving some attention to weight. The drawing appears to show batten seam construction which adds weight and extra building labor. Have you considered glued lap strake that will eliminate the battens and also produce a cleaner interior? If 'twas from my drawing board it would have inwale stringers for additional sheer stiffness
     
  4. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    Hi, Messabout

    And thanks for the compliments. The weight considerations are there, but not first on the list. The main goal is to design a boat that would be easy and relatively fast to build at boat building courses, like Niko (https://www.youtube.com/watch?v=h8NxchEC5x4). 6mm planking (with Vendia) is sturdy enough, yet light and easy to work with. And 1/3 cheaper than 9 mm stuff, which would be the choice if the boat is to be used heavily.

    The boat could be built considerably lighter and still durable enough, if the ISO-scantlings were forgotten. But that was one of the requirements in the design... (the minimum design pressure of 5kN/m^2 makes it heavier than required for stiffness).

    About the labor, I think that the battens are easier to shape for the first-timer, than the gains (in lap strake method) in the plank ends in thin planking material. I might be wrong, of course. The battens are a nuisance when varnishing or washing the interior, that's true. When one bows to one direction, at the same time he bends over to another.

    The inwale stringers (with a capping to form a narrow side deck to sit on) will be an option, if the boat will be fitted for sailing. For rowing only, it is stiff enough as it is in the picture.

    I have been busy with another project, so not much of a progress here. The sail plan and the appendages are under work now.
     

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    Last edited: Sep 7, 2016
  5. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    The structural design is just about finished, here's how it should go together:
     

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  6. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    The building of the prototype has begun. I'll add some photos here every now and then. Here are the frames, knees and stem, and some templates for the transom and planking. Hopefully everything clicks together nicely.
     

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  7. SukiSolo
    Joined: Dec 2012
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    Location: Hampshire UK

    SukiSolo Senior Member

    Nice job Jarmo, well done. I personally would add some good size limber holes though so water drains through and can be removed properly. These will not be easy to 'retrofit'!
     
  8. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    Hi SukiSolo,
    The limber holes issue was solved by making the frames 10 mm off the planking, they are not attached to it. It also excludes the possibility of the "hungry-horse-look", when the frames can't be left proud and produce kinks to the planking.
     
  9. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    Here are some pics of stem and knees under fitting. There is also a more traditional version under design process. It will be of carvel or clincker pine planking over steam bent oak or ash frames.
     

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  10. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    The frames and the stem were erected on the jig last week. She's starting to show her shape. Fitting the stringers is the next job.
     

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  11. tmark
    Joined: Sep 2006
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    Location: Stratford

    tmark Junior Member

    I like this rendering a great deal. Did you generate it? If so, I'm curious what program you were using.

    Edit ... hmmmm ... my comment didn't seem to pick up the picture I was referencing ... its the black and white perspective drawing in post 2
     
    Last edited: Jan 27, 2017

  12. jarmo.hakkinen
    Joined: Jun 2007
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    Location: Kerkonkoski

    jarmo.hakkinen Junior Member

    TMARK,
    Yes the renderings are made by me. I use Rhinocecros 5, that rendering mode is one of the standard ones, "pen". There is a lot you can adjust, background, shadow density or style, line widths, jaggedness... And you can create your own modes of display too. And get a set af jpg:s for making an animation, see this: https://www.facebook.com/jarmo.hakkinen.1/videos/1213906745354444/
     
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