Solitude - Modelling a Sit-on-Top Stitch and Glue Kayak

Discussion in 'Boat and Accessory Building' started by mick_allen, Feb 12, 2008.

  1. Roy222

    Roy222 Paddler

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    That is one really cool Kayak - WOW - WOW
    It is a fantastic work of art, in every sense.
    You have broken open a whole new world of Kayak Design!
    That bow is crazy cool.
    If vikings had Kayaks, Viking kayaks would look like the WAVECREST !

    Can you just imagine showing up at a Chesapeake Light Craft event with that Kayak!

    ( actually CLC's build method is an ideal construction method for that design)

    That Kayak has to be built - it just does!
    Your Wavecrest could raise a lot of attention and money for bcmarinetrails!
    That design would draw people to bcmarinetrails, who normally would care less about boating and remote camp sites!

    "Just Build It"
     
  2. JohnAbercrombie

    JohnAbercrombie Paddler

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    Mick:
    Do you print the panel shapes (plans)?
    On paper or Mylar?
    Yourself or at a jobber?
    How thick is the plywood that you use? And what type of ply? How do you get it to twist so sharply? Heat?

    Inquiring minds want to know!!
    :)
     
  3. mick_allen

    mick_allen Paddler & Moderator

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    I found it very difficult to develop that kayak in a usual 3d method because of the difficulty of keeping fairing control when surfaces stepped down or up and panels crossed fairing 'lines'. So it was mostly developed by a classic 2d approach with plan/elevation/section/endview first - and from that setup 3d sections were developed.

    So doing it that way, NO panel shapes were drawn or developed first - only forms. The forms were then erected on a typical internal spine - and from that setup spiled cardboard [for both model and full-size] and then doorskin patterns were derived [for full size only] which were traced onto dark stained ribbon grain mahogany 1/8" thick ply [the model used .06" styrene sheeting]. A slight variation on an old traditional wood boat strake shape approach.

    The design aesthetic is to exaggerate the lapstraking as that was what reveals the form. So although 1/8" ply, all joints were raised by epoxy mush and wood bits to achieve the min. 1/4" lapping approach. [I remember calculating that the overall weight hit would be in the order of 1 lb or so]. The bow underneath has wonderful deeeeeep reverse lapping [that lines up and meets the deck traditional lapping] that was achieved by injecting foam in the lap, smoothing off the lap face and putting black epoxy [ie shadow lines] over just the lap. All laps used black epoxy filler to maximize the effect. The unbelievable twist was achieved by glassing the ply face and locally routing off all the non face veneers rendering a literal piece of spaghetting at that location on the panel. But I would have just made one or several cross panel seams if it looked like it wouldn't have worked.

    The tail was/is the most difficult as single panels curve up and around the whole kayak shape and so major veneer removal was used . . . when split, these areas will be backed up with a multitude of extra layers of glass. There are lots of errors in this location unfortunately.

    For most of my models [1/4 full size], I use a print service that I'm fairly familiar with - and because I have a little foreknowledge of print variability, I have no qualms with paper prints.

    Oh yeah, edited to add: that kayak is not a serious kayak to anyone except myself: although the bow and stern is blunt there are lots of little edges to catch, the entry is bluff, there is minimal rocker except at the ends, knee/paddle position is wide, strakes don't butt but are relieved, strakes end in reverse curves, hatches match cockpit shape, it'll be a slammer, etc. etc.
     
    Last edited: May 27, 2019
  4. JohnAbercrombie

    JohnAbercrombie Paddler

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    Thanks, Mick-
    That idea of erecting forms and then spiling the panels has been used by some builders to 'convert' strip designs to S&G - I think the Black Pearl has been built this way, with ply (before the S&G models were developed) or with 'panels' made from strips. It's difficult to get hard chines with ordinary strip construction.
     
  5. mick_allen

    mick_allen Paddler & Moderator

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    lo and behold, I actually have one spiled card panel pattern left from the facetious build. It's not a very good one for demonstration as it is that last panel to the straight centreline and derived from the edge of the panel before. The idea is that the pattern is made smaller than the gap and is pieced together to follow the lines of the vessel/positive shape, then little legs are extended out to be flush to the surface of the previous panel. Then is overlaid on the actual building sheet, that is marked with darts from the ends of the card extensions, and using french curves or other fairing devices all the dots are connected and then the panel is cut out. I just used a dozuki saw and cut just outside the line and planed or drum sanded down to it.

    Facetious-spiling.JPG

    And that's how I made facetious back in the day before I was familiar with a usable surfacing program. So drawn in 3d, but only could use 2d take-offs. So forms were erected from the 3d drawing and as you state above, spiled panels were taken from the progressive construction on the build. Soon after that I had a good surfacing program and derived digital panels and made a 1/4 full size proof of concept model to assure that it works just as well that way.
    Facetious-model.JPG
    [the model is styrene plastic but paper covered and quite grubby now after all these years, but it is a true demonstration of the reality of use of this digital approach]