stitch and glue + -

Discussion in 'Boat Design' started by William C. Wins, Dec 29, 2011.

  1. Milehog
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    Milehog Clever Quip

    Built something like this perhaps? CLICKY
     
  2. upchurchmr
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    upchurchmr Senior Member

    Sounds like it from the description. Wish they showed at least one section so I could see the shape. Do you know if this is sharpie like (flat bottomed) or a shallow V?

    My personal bias is aimed at a trimaran so much narrower on the bottom.

    Marc
     
  3. Milehog
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    Milehog Clever Quip

    IIRC it is a sharpie with a relatively tight strip planked bilge radius.
     
  4. ancient kayaker
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    ancient kayaker aka Terry Haines

    For S&G you must have the plank developments; are you paying the designer extra to generate those and adapt the design to suit the S&G method? With S&G you will be handling full length planks, worrying about temperature, fast and slow mixes, glue working time and batch size. A large epoxy mix can set up smoking hot in seconds. S&G is lighter but Iā€™m wonder how relevant that is to a tug unless you plan on towing it.

    With ply-on-frame you can build the frame from the offsets that you already have and plank up one ply sheet at a time, butt or scarf joining as you go. The frame needs marine quality material unlike the throw-away station molds required for S&G, but there will be bulkheads so you might not save much. The extra cost of the chine logs will likely be less than the cost of the epoxy filleting material, and you can work at your own pace with no worries about temperature, work time of adhesives and so forth.
     
  5. rwatson
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    rwatson Senior Member

    Cant see what you are getting at here. You don't have to do the whole lot at once - you can do it in small sections.
     
  6. marshmat
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    marshmat Senior Member

    The only fibreglass work in S&G that really ought to be done in one shot is the final outer skin. You can do everything else by yourself, one seam at a time.

    Don't fret about epoxy working times or batch sizes, it's pretty simple to keep it under control. Mix at most a half-litre (two cups) of the stuff, use it, then mix more. If it's going off too early, it's because
    (a) you made far too much (only make more than a half-litre if you're going to dump the whole bucket out all at once), or
    (b) your glue guy sold you the fast/winter hardener when he should have sold you the slow/summer stuff. (Make sure you get the right one the first time.) I just always use the slow kind and find something else to do while it sets.

    As for wood/epoxy composite versus traditional: I tend to pick the epoxy-composite version, because I prefer the resulting lower-maintenance hull (and the ability to cover up occasional sloppiness during the build without any adverse effects). Unsealed wood and mechanical fasteners are perfectly fine, if you like taking care of a traditional wood boat. The choice is, of course, up to the builder, and both methods- if done properly- are plenty strong and safe.
     
  7. ancient kayaker
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    ancient kayaker aka Terry Haines

    - must admit I haven't had those problems myself. I don't do S&G, just passing on potential problems based on what I've seen and read of other's experience. I'm not tryng to promote traditional methods either - I don't do that as I'm more into the wildly experimental . . .
     
  8. rwatson
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    rwatson Senior Member

    That's true - and even the final skin can be done in a progressive manner.

    You can start at one end, and by the time you get to the other end, the first bits may be going off, but it doesn't matter.

    Even the outer skin can be done in sections on big boats. There is always overlapping sections, and you can do one complete 'sheet', and overlap the next one on a later date.
     
  9. michael pierzga
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    michael pierzga Senior Member

    Another detail that's troublesome with stitch and glue is the size of the plywood panels. Difficult for a one man boatbuilder to handle floppy 20 ft long ply panels in a small shop. Takes patience and many coffee breaks.
     
  10. ancient kayaker
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    ancient kayaker aka Terry Haines

    That is what I understood and was referring to in my earlier post, but more recent posters seem to have said otherwise. I don't see how planks can be applied one sheet at a time in the S&G method. From my own experience helping a buddy with a S&G build, it can be difficult to handle full-length planks alone without breakages, depending on their shape and thickness.

    My own method is to glue inwales and chine logs to the sheer planks while they are flat which makes them stronger and easier to handle; the bottom plank is wider and easier to handle and the bilge planks can be added in sections. This works well for small boats and thin (3-6 mm) ply but, since thickness of ply and chine log both increase, in a larger boat the resultant plank becomes too stiff to bend without breakage.

    Also, in a large, robustly-built S&G boat the planks must surely get rather heavy and an awful lot of space is needed to join the sheets into a full-length plank and leave room for a partially-built boat . . .
     
  11. michael pierzga
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    michael pierzga Senior Member

    Yah..Its a skill. Its doable without a doubt...just intimidating when you build your first 20 footer.

    I think all boat building is intimidating your first time.

    Saturating glass cloth ? Yikes !! Not difficult, every builder can do it, but its intense, arms flying, stand aside or lose a limb work.
     
  12. upchurchmr
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    upchurchmr Senior Member

    Michael,

    Have you ever done S&G?

    I have only done a kayak which is rather small panels, but "arms flying"??? Sounds like you had a bad dream not a real experience.

    "Saturating glass" is the simplest most trivial job I had on S&G or on strip planked (kayaks).

    Why does anyone need to hurry? Just keep working from one end to another with deliberate (reasonable) speed leveling the epoxy as you go. No need to get excited since if the first end is curing while you are finishing the final end - what do you care? This would be the best possible scenario since you need to add a second coat to fill the weave while it is not fully cured.

    Same comment about floppy panels, but this probably would be more difficult in a large size boat. But still, making this stuff sound like it should make or break the choice of method?

    Perhaps you should look at the Core Sound build sequence - doesn't look too difficult to me. There also was a recent post about a scaled Phil Bolger single handed schooner - wasn't any evidence of loosing limbs there. ( actually that was the next post down as I was reading - a great build sequence).

    The reality about S&G is it gets choosen because of its apparent simplicity - it is a great way to get started.

    Marc
     
  13. PAR
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    PAR Yacht Designer/Builder

    Once a builder gets a handle on the procedures and processes in a taped seam build, there's no more difficulty then with other methods. Handling large panels isn't especially difficult. I've hung 24' plywood planks, all scarfed together by myself with little issue. Lifting one over your head, just to keep the ends from dragging on the floor can be an issue, but not an insurmountable one (wrap the ends). In craft less then 20' long, this isn't a problem at all. The planking or panel thicknesses in these sizes are thin enough so the weight isn't an issue.

    As Marc has mentioned, most taped seam designs have you assembly and fold the pre-joined "plates" on the floor or a "buck" (jig), which greatly simplifies the tasks. The hard part is getting enough seam reinforcement on and "squaring up" the hull shell so it's reasonably symmetrical, when the internal stiffeners go in. It's this last point that I see the most problems for the home builder. They assembly the raw shell, but it's a floppy and warped assembly of panels until the seat boxes, bulkheads and other stiffeners go in. Getting it into a building jig or cradle, that's level and forces the floppy panels into proper alignment is crucial for a symmetric hull. Sheathing is fairly easy for most folks, assuming some procedural steadfastness.
     
  14. rwatson
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    rwatson Senior Member


    Yes - you are right. The long panels are awkward, and require planning to assemble. They can also be heavy when doing the larger sizes of plywood - as you would use for a tug.

    One web site explains how the builder created rolling stands to hang the panels from, to present them to the frames.

    I am relying on a 'basket' to retain the panels, and an overhead hoist to lift them off the assembly table.
     

  15. eyschulman
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    eyschulman Senior Member

    If you look at picture of my earlyer post of Sam Devlins crew putting 48ft+ ply plank on my boat notice wood supports off bulkheads to hold plank and considerable bend in 8mm ply. I would think on a 20ft boat two could easily use this method. A few temp. screws into bulkhead and some wedges on support wood from bulkheads to get the plank where it can be wired and glued. A secound set of ply planks sl thiner was placed over the first layer with temp fastners and blocks as below. It must work Sam has built like 400 boats the larger ones probably use this method and they hold up well as far as I am aware.
     

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