Plywood Kits without stich and glue

Discussion in 'Boat Design' started by chris.dymond, Dec 11, 2013.

  1. chris.dymond
    Joined: Oct 2008
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    chris.dymond 4.8 metre Sailing Dingy

    I am redesigning a plywood kit I created some time ago.
    This time to reduce build time I am obsessed with clipping the hull panels together to remove stitch and glue - any ideas

    This is were I am up to......
     

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  2. michael pierzga
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    michael pierzga Senior Member

    i Dont understand...you mean eliminate the stich and only use a filet ?
     
  3. chris.dymond
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    chris.dymond 4.8 metre Sailing Dingy

    I'm sorry I should be clearer. Still glass tape and fillet, but no needing the wire or cable ties
    to hold it together. So.... using slots,tabs and wedges (or pins) that are later trimmed off
    Ive seen it used for other applications and one kit boat
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Chris, you're attempting what many of us have been exploring for some time. Interlocking seams, zipper and dog bone joints, etc. I don't use stitches very much in this type of build, though sometimes they are handy to pull something together. Your notch and tab approach looks like several other accessions to this set of issues, which work best in CNC format, naturally.

    The notch and tab technique does require a slight bit more room in the nesting arrangements in the cut file, but does work. I use a simple short block of wood, arranged along an edge, which the next panel rests against, before the seam is filleted and tabbed. I find this easy to place the usually 2x2 blocks (temporary attached hot glue or drywall screwed) and I can do most of the seam. Your technique, means the whole inside seam can be done in one shot (unlike my system), which is good. My block system permits the whole outside of the seam to be done at once, while yours requires some trimming first.

    As to which is more effective, particularly in light of the others also available, well this is probably pretty subjective, though the zipper seam does let you do both sides of the seam unobstructed.
     
  5. tom28571
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    tom28571 Senior Member

    Yes, that system has been around for a long time. Way before anyone thought of applying it to boats when paper dolls and toys were done that way as far back as the 1930s' in my experience. Some boat kit makers are doing it now and only CNC makes it practical. I can say that the number of tabs on your chines and other areas is not adequate and many more are needed to hold the boat in correct alignment to the design offsets.

    Maybe best not to be stuck on a single system and do what is most suitable for a given boat and part of that boat.
     
  6. midnitmike
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    midnitmike Senior Member

    I recently finished construction of a 13'6" hull that utilized no stitches whatsoever thereby eliminating all of the holes and stitches normally associated with this method. The panels were simply hot glued together along the seams on the outside leaving me free to apply a continous fillet and tape join on the inside surface. The main difference between our construction tecniques is that I used fiberglass flat sheets instead of plywood for my panels. A set of temporary plywood frames were installed in the interior to hold the panels in alignment until the transom and bow pieces were in place. Once all the hull panels were fitted and bonded together full length lay-ups were made along the sides and bottom to tie it all together.

    This is an experimental project that I under took to help me work out the bugs in the process before moving on to a slightly larger and more complex version.

    MM
     

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  7. messabout
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    messabout Senior Member

    OK I assume that we are talking wooden boats here. Ply skins almost surely.

    Curmudegeon that I am, I have long argued that S&G construction is a PITA. You can build a boat more accurately, and just as quickly the old fashioned way. Cut out some former/mould frames, Align them with easily achieved precision, (try that precision thing with precut panels that you hope will actually conform to the designed shape), nail some ribbands to the section formers, fair the ribbands as needed, Now the panels are easy to layout and can be marked off with high precision because the ribbands guide the marking. Staple or temporarily nail the skin to the frame/ribband structure.

    Yes we will use a fillet and glass ribbons on the inside when you remove the boat from the forms and turn it upright, with only ribbons on the outside. You epoxied the seams but only as the ply meets ply at their faying surfaces. You did put some simple wax paper over the ribbands where the epoxy will be, didn't you? That join is good enough until you get the filleting done on the inside joints. In some cases you will build an external former to hold the flare and the attendent rocker. Fasten that temporary former from the inside out with temporary screws. Turn the boat over and finish the inside.

    In all this you have not had to lay out some hopefully correct shape on scarphed panels, drilled a zillion holes, pulled a zillion wires, or eyeballed the wire joined panels into hopefully correct shape. Few if any holes to fill.

    Suppose you want to build a flat bottomed or vee bottomed hull with radiused chines. No problem. Round the chine areas on the station moulds and strip build the radii. After that, proceed with marking out your ply panels right on the form, and go for it. Can't do the radiused chined with conventional stitch and glue. This is still an epoxy/glass reinforced joining scheme and it is simple. Clean interiors a bonus.

    You get a very good grasp of this method in Tom Hills nice little book; Ultralight Boatbuilding.

    The alternative to the pain of lofting or laying out a series of S&G panels, if you are determined to use a micky mouse stitch and glue method, is to bite the bullet and buy kits from Chesapeake LightCraft, Guilemott, or other precut panel sellers. You still have to drill a lot of holes, pull a lot of wires and all that. Better to have been building the boat in a time tested but slightly modified way. I have done it both ways. No way I'll do another stitch and glue boat. The older way is faster and much more rewarding.

    Rant conclude. I hope it might engender a modicum of consideration.
     
  8. tom28571
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    tom28571 Senior Member

    You could possibly make your points and advance your preferences without putting down other methods you may have inadequate experience with.

    All boatbuilding methods have their good and less good points. I have used them all, sometimes in various parts of the same boat. Calling S&G "micky(sp) mouse" runs counter to the experience of thousands of other home and professional builders. While all of my designs use epoxy/glass/plywood for most joins, not all are S&G. I do also enjoy making shavings and agree that it can be most rewarding but will usually opt for the most appropriate method for each task.

    Even a curmudgeon can and should maintain an open mind.
     
  9. lewisboats
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    lewisboats Obsessed Member

    Lots of "Stitch and Glue" designs have little or no need for "stitches" A gentle easy curve can be held in place with Duct Tape or a cable tie every foot or so. Hot gluing is another option as is pinning in place with small finishing nails. It is only necessary to use closely spaced holes and lots of ties or wires when pulling together tough bends and when warping or torturing the ply into difficult shapes. I have seen people stitch together box boats with 1 stitch every 3 or 4 inches... ridiculous! A stitch or tie every couple of feet and some duct tape to keep things aligned and away you go. 90% of S&G builds I have seen have had 2-3 times as many "stitches" as was actually necessary to hold the panels together long enough for the fillets to cure. Lofting panels is just as easy and going through setting up build frames, and cutting and fitting all the rest of the pieces of wood that have been mentioned in order to get the shapes. A combination square, a 4' metal rule and a decent batten and you can lay out a panel in 15-20 minutes from offset #. All it is is plotting a curve on a graph... except on plywood instead of graphing paper.
     
  10. michael pierzga
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    michael pierzga Senior Member

    I still cant visualize a technique to hold the panels stationary and to shape without some kinda stitch.

    As was mentioned hot melt glue as the stitch sound ok for a boat with little shape.

    A basket mold might be worth thinking about.
     
  11. rwatson
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    rwatson Senior Member

    The use of tabs to accurately position frames, bulkheads etc is very commendable.

    Trying to remove the use use of wire ties etc, just for the sake of it, is not a valid reason in my eyes. They are a very useful technique in the right situations, as others have explained very well.
     
  12. latestarter
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    latestarter Senior Member

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  13. michael pierzga
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    michael pierzga Senior Member

    Well the tape is acting as a stitch......

    The hot melt glue stitch sounds doable.
     
  14. Milehog
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    Milehog Clever Quip

    Super glue too.
     

  15. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    I wonder if these might work, they're called hog rings and hog pliers. They are used in upholstry, for one thing.

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