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Thread: Skin on Frame Peapod

  1. #1
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    Default Skin on Frame Peapod

    My current project is a 12ft Skin on Frame Peapod. I want a light weight boat that is economical with the materials easily available in the UK. I have discussed construction here:
    http://forum.woodenboat.com/showthread.php?240158-Construction-method-costs


    The final method chosen being SOF with 4 or 5 frames and 4 stringers per side. Frames, Keel and Gunwale will be 12mm ply. I will need a whole sheet and optimise the design to fit on this one sheet. Other timber will be Ash

    Ball park DelftShip design

    LOA 3.6m > 11’ 10”
    Beam 1.2m > 3’ 11”
    Draft 0.1m > 4”
    Displacement 140kg > 308lb
    Midships depth 0.4m > 1’ 4”


    The boat will be symmetrical fore and aft as per this discussion
    http://forum.woodenboat.com/show-thread.php?240131-Double-ended-dinghy-symmetry

    The rig will be a modest balanced lug so CE forward and the dagger board and mast partner can be easily tied together




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  3. #3
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    Default

    Lots of improvements to hull shape required but CAD model enough to try and nest all the 12mm ply onto one sheet



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  4. #4
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    Feasibility layout of ply as a test done
    Proves can all be got from 1 sheet 12mm ply
    Space to join the frames ie port and starboard frame would slot into keel, not separate as drawn
    Plus gunwales and boards etc



    Modifications required to the actual hull shape next and then lots of detail design work




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  5. #5
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    Default Re: Skin on Frame Peapod

    Wow, looks fancy! How much do you reckon the bare hull will weigh?

  6. #6
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    Default Re: Skin on Frame Peapod

    Cool Tink, looking forward to your build.
    "Yeah, well, that's just, like your opinion man"
    -The Dude-

  7. #7
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    Default Re: Skin on Frame Peapod

    What I have at the moment is 20kg (44lb) I figure 30kg without the skin and removable bits.

    Thinking a sheet of proper Okoume (£112)
    Timber Ash if I can get it some a reasonable price, or construction grade pine est (£50)
    Removable PVC skin (£40)

    So £250 - £300 > US$330 - US$330

    Lots of detail now but happy with the concept

  8. #8
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by Small boats rock View Post
    Wow, looks fancy! How much do you reckon the bare hull will weigh?
    Thanks, long way off a build. SOF may be quick build but it is very time consuming to CAD up compared to S&G.
    I will want to make an accurate scale model to find any errors before committing. Time rich at the moment due to a few health issues so keeps me in the game.

  9. #9
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    Scrap concept model of the frame to keel join.

    > allows building without any form of frame
    > despite slot strength of frame and keel maintained
    > allows for non epoxy construction
    > plans for ‘what if’ frame not stiff enough, additional stiffening can be added



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  10. #10
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    Probably about 5 hours of work in this one photo

    Lots of accurate detail behind the seen




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    What I get up to
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  12. #12
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    Default Re: Skin on Frame Peapod

    The keel stiffener might be easier to fit if you make it one piece with a shallow lengthwise slot to fit the keel. It will also provide a wider flat surface that will be easier on the skin than a narrow keel.

    EDIT: Yes. Exactly as pictured in post #13.
    Last edited by MN Dave; 06-26-2018 at 11:16 AM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  13. #13
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    Default

    Quote Originally Posted by MN Dave View Post
    The keel stiffener might be easier to fit if you make it one piece with a shallow lengthwise slot to fit the keel. It will also provide a wider flat surface that will be easier on the skin than a narrow keel.

    Yes a nice idea, I resume you mean something like this




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  14. #14
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    A day on the design while recovering from an operation was VERY tough but helped




    https://tinkboats.wordpress.com
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    What I get up to
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    https://youtu.be/oni-3rJzxqQ Sail Canoe
    https://youtu.be/eW078PPgJak Proa

  15. #15
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by tink View Post
    A day on the design while recovering from an operation was VERY tough but helped
    Whatever the op was for, I hope you recover quickly and well.

    Nick

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    Thanks Nick

    Today’s effort, gunwale, board trunk and thwart in.

    Going to calculate weight and then probably start removing bits



    https://tinkboats.wordpress.com
    http://proasail.blogspot.co.uk
    What I get up to
    https://youtu.be/X9NZEyvpb_Y Streaker dinghy
    https://youtu.be/oni-3rJzxqQ Sail Canoe
    https://youtu.be/eW078PPgJak Proa
    Last edited by tink; 06-28-2018 at 06:34 AM.

  17. #17
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    Default Re: Skin on Frame Peapod

    Big spread sheet produced current material on frame 30kg (66lbs). Not bad but lots of improvements possible
    > Replace side deck with better, lighter ‘ladder construction’
    > Review solid timber flexural rigiditity vs weight - WRC, Doug fir, Ash
    > Scantlings of solid timber especially gunwale
    > Make dagger board off center to retain keel stiffness
    > Review board sides material / thickness

    Confident that I can get down to 25kg

    Metarials bought for accurate 1/12th scale model

  18. #18
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by tink View Post
    Big spread sheet produced current material on frame 30kg (66lbs). Not bad but lots of improvements possible
    > Replace side deck with better, lighter ‘ladder construction’
    > Review solid timber flexural rigiditity vs weight - WRC, Doug fir, Ash
    > Scantlings of solid timber especially gunwale
    > Make dagger board off center to retain keel stiffness
    > Review board sides material / thickness

    Confident that I can get down to 25kg

    Metarials bought for accurate 1/12th scale model
    This is about 30 kg.

    • Length: 10'
    • Beam: 50"
    • Weight: 60lbs
    • Walnut Transom & White Oak Frames
    • Easy to maintain oil finish
    • 9oz ballistic nylon skin


    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  19. #19
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    Default Re: Skin on Frame Peapod

    Nice, is that yours? Reworking the CAD, editing it is a time consuming and laborious task

  20. #20
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by tink View Post
    Nice, is that yours? Reworking the CAD, editing it is a time consuming and laborious task
    Would it be easier to go for steamed ribs, instead of plywood frames?

  21. #21
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by sailnstink View Post
    Would it be easier to go for steamed ribs, instead of plywood frames?

    Based on the availability of suitable timber in the UK (or at least that I can find) bent frames are an very expensive option. I also believe that the plywood frame method is a much quicker build at the expense of a complex design process. At the moment I have lots of free time hanging about with my iPad so can explore the and optimise the CAD design and I am enjoying the process.

    Aesthetically I do prefer the bent ribs method and a have found a mill nearby that sells Ash planks and a do plan to go an see what they can offer

  22. #22
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by tink View Post
    Nice, is that yours? Reworking the CAD, editing it is a time consuming and laborious task
    No, I only cut out the blanks for the seats and made the oars. There was a link to the boat: "This is about 30 kg." I thought it was sold, but apparently it is still there.

    I googled 'ash wood planks for sale near newcastle upon tyne' and found several suppliers in that area.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  23. #23
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    The accuracy of Google is not close to what it promises. The bottom one one the google list a carpet shop.

    I have been through every result for ‘Timber’ within fifty miles and have one good lead and semi good lead I just need to get out and visit them. This is the most promising and I will visit soon.

    For the moment I am a bit restricted in what I can do physically so enjoying the mental work out of the ply frame design.





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  24. #24
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    New gunwale design and stringers now 3/4 x 3/4 Doug Fir which is 1.4 times stiffer than 1 x 3/4 RWC.
    Whole boat timber and ply 23kg 50lb.




    https://tinkboats.wordpress.com
    http://proasail.blogspot.co.uk
    What I get up to
    https://youtu.be/X9NZEyvpb_Y Streaker dinghy
    https://youtu.be/oni-3rJzxqQ Sail Canoe
    https://youtu.be/eW078PPgJak Proa
    Last edited by tink; 06-29-2018 at 03:26 PM.

  25. #25
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    Default Re: Skin on Frame Peapod

    Douglas fir is stiff and strong, however in my experience it is best suited to straight components. Not that Douglas fir can not be made to take a curve, but there might be better options. Can you source yellow cedar by any chance?

    Whatever the case, your design detail is looking terrific!

  26. #26
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by Small boats rock View Post
    Douglas fir is stiff and strong, however in my experience it is best suited to straight components. Not that Douglas fir can not be made to take a curve, but there might be better options. Can you source yellow cedar by any chance?

    Whatever the case, your design detail is looking terrific!
    Thanks, I will take what you say on board, hoping to souce ash just need to get to a mill I have found on the net.

  27. #27
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    Board support and thwart etc added, lots of work required to get it all to fit on one sheet which is my challenge





    https://tinkboats.wordpress.com
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    What I get up to
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    https://youtu.be/oni-3rJzxqQ Sail Canoe
    https://youtu.be/eW078PPgJak Proa

  28. #28
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    Bit of a rethink
    Played about with separate frame halves which structurally and build complexity I don’t like.
    Still won’t t all fit on one sheet and doesn’t include anything for the rudder.


    Looks like I would need to go to 1 1/2 possibly 2 sheets and if that is the case I have to benchmark against all ply construction

    I have plans for Selway Fisher Swapscott 12
    “The first Fisher Swampscott 12, with a length of 12ft and beam of 4ft 2 inchesand narrow tombstone transom and with 9mm bottom and 6mm planks (lightweight Gaboon ply), with 6mm ply for the seats etc, came out at just 66 lbs. in weight and took only 30 hours to build (including all marking out). She took just 2 sheets of 9mm and 2 sheets of 6mm exterior or marine ply plus a few lengths of Douglas Fir. Because of her light weight, she was easily car topped”
    http://www.selway-fisher.com/Other1013.htm

    And the Arch Davis Maine Peapod has a lot of appeal

    “The peapod uses three sheets of 8’ x 4’ x 4mm marine plywood for the planking, 1 sheet of 1/2inch plywood for the station molds, some lumber, epoxy resin, fastenings, and some hardware”
    http://www.archdavisdesigns.com/davis_peapod.html
    This can’t include ply for foils I am sure

    SOF - 2 sheets 12mm £192
    Ply design
    3 sheets 4mm - £129
    2 sheets 6mm + 1 sheet 9mm - £179

    So putting the SOF on hold until I understand what I can accomplish with 3 sheets of ply.


    https://tinkboats.wordpress.com
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    What I get up to
    https://youtu.be/X9NZEyvpb_Y Streaker dinghy
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    https://youtu.be/eW078PPgJak Proa
    Last edited by tink; 07-01-2018 at 02:53 AM.

  29. #29
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    Default Re: Skin on Frame Peapod

    here's some further inspiration, prehaps. I spotted it by the harbour the other day. only about 6-8', and that's cotton canvas on there.


  30. #30
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    Default Re: Skin on Frame Peapod

    Lovely. Watching.

  31. #31
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    Default Re: Skin on Frame Peapod

    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  32. #32
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    Default Re: Skin on Frame Peapod

    Quote Originally Posted by MN Dave View Post
    thanks, that is very impressive, as a design do feel it is not the most effective use of plywood

  33. #33
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    Default Re: Skin on Frame Peapod

    No, Stefan is the most efficient.
    http://flo-mo.weebly.com/three-sheet-boats.html
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  34. #34
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    Default Re: Skin on Frame Peapod

    True

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