Strip planking newbie question

Discussion in 'Wooden Boat Building and Restoration' started by JordieS, Oct 7, 2011.

  1. ancient kayaker
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    ancient kayaker aka Terry Haines

    - that sounds wasteful and a mess on the floor to clean up unless sawdust was laid down first to soak up the spillage, on the other hand for a large boat-building job it would certainly be hard work to do all those kilometers of seams. I will probably set up a small scale test first and try both ways out. I like to look for boat-building short cuts . . .

    BTW referring back to an earlier post suggesting the stripped interior is rough unless self-aligning strips (T&G or cove & bead) is used: I did not find this to be the case with my first stripper, using square edge strips. If the station molds are close enough the strips line up well: I used 8" (20 cm) centers. Biggest hassle is the glue squeeze-through inside, I would like to avoid that next time. The outside is far easier to sand.
     
  2. garren
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    garren Junior Member

    If your bevels are good and strips are "tight," do you need an adhesive for a boat living on a trailer? Could something sticky like a mixture of turpentine and pine tar (or something else) spread on the strips be used to minimize leakage?

    Gary
     
  3. LP
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    LP Flying Boatman

    The original strip-built hull did not use adhesives or sealers per se. Swelling of the strakes provided for water tightness.
     
  4. garren
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    garren Junior Member

    I'm curious whether boats that may not be in the water long enough to sufficiently swell tight, e.g., maybe a half-day river float, could benefit from some sticky sealer as mentioned above to minimize leaking. Its likely not a big deal if the boats leaks on such trips - bailing is not uncommon. Generally, would applying such a mixture between strips be deleterious?

    Thanks - Gary
     
  5. ancient kayaker
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    ancient kayaker aka Terry Haines

    If both sides of a stripper are covered in glass fiber then the adhesive between the planks merely has to hold it together while the glassing is done, carpenter's glue is often used.

    Obviously an unglassed stripper needs ribs for cross-grain strength, so does a lapstrake boat unless it's made with plywood planks per your thread on that subject, these can be fastened together with copper rivets and roves, or copper canoe tacks can be used, but that's a more challenging process than gluing.

    I haven't used them but the cost of the copper bits will surely exceed the cost of the epoxy.
     
  6. ancient kayaker
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    ancient kayaker aka Terry Haines

    A further thought; epoxy and other modern adhesives have a shear strength of around 4000 psi which is several times that of wood species typically used for strip building. If a stripper is going to be glassed inside and out, the glue between the strips merely has to hold the strips together during the handling and sanding prior to glassing. So I am wondering if something a little cheaper and easier to sand can be brushed into the gaps after dry-stripping the hull, thick shellac for example or even wood filler.
     
  7. rwatson
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    rwatson Senior Member


    a quote from another thread you may or may not have seen -

    "You may liketo check out this link for an interesting and easier way to strip plank"

    http://bowdidgemarinedesigns.com/Bow...ng_Videos.html

    he uses thickened epoxy with easy to sand fillers into a fully dry layup, but he doesnt put much twist on the planks.

    But doing that on a kayak or smaller boat may be trickier. I can remember when I had to wait till my Purbond Glue ( Gorilla Glue in the US) - which is really easy to sand after hardening - had to set first, to hold some radically twisted strips before I could go onto the next strip on the hull.

    For the few 'pennies' that you spend on the glue per craft ( I think $30 for glue on an $800 materials bill ) - it seems crazy to risk all that work on experimental products.
     
  8. LP
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    LP Flying Boatman

    I think Terry's goal(s) is/are to minimize the use of epoxies in his construction techniques and to also reduce the labor/time involved in strip building. I don't believe his perspective is from a financial viewpoint. I too am onboard with simplified strip construction.

    If I am remembering the proper video, he is using the strips as a core and has an FRG layup schedule that is the true structure for his build.
     
  9. ancient kayaker
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    ancient kayaker aka Terry Haines

    RW: I have seen that video. LP is correct, it isn't the cost that bothers me as much as as the effort required to sand the hull fair as the epoxy is much harder than the wood and the wood tends to get sanded away between the lines of epoxy unless considerable care is used. Your point about the ease of sanding fully set Gorilla Glue matches my experience with it - although it is not as good as the manufacturer's claims.

    Experimenting is what I do, as I am always looking for improvements to the status quo. It keeps me off the streets . . .

    You other point about the difficulties with twisted planks is also something I am looking at; my recent designs minimize or even eliminate twisting. What I am looking forward to discovering, following launch of one or two boats, is the impact on the boat's characteristics.
     
  10. sabahcat
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    sabahcat Senior Member

    Have you tried it as per the comment?
    FWIW I did my hulls with straight resin (no fillers) and backfilled while green any lows with a Qcell & wood dust blend.

    I had no problems whatsoever sanding the hulls using 36 grit "Blue Magnums" on a 2 speed sander with absolute minimal timber being sanded away
     
  11. ancient kayaker
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    ancient kayaker aka Terry Haines

    Not yet: I was quoting what I had read by others, and a buddy found that sanding fairing epoxy was hard work on his boat but that may not have used the same type of filler. My current build uses Titebond III, which is also not an ideal adhesive for the job IMHO. A lot of people building strippers seem to use ordinary carpenters glue which I have found seems to smear and/or clog the sandpaper.

    If I recall correctly you were using a thin epoxy to penetrate deeply into the gaps between dry-assembled strips; that is something I would like to try in a future build - I am still looking for the best method for my purpose.
     
  12. rwatson
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    rwatson Senior Member

    You lead me astray by saying ..


    I would be interested in knowing if Gorilla Glue is the same as Purbond - I was very happy with its ease of use, strength and sanding qualities

    If it wasn't so wasteful in materials, I have often thought of doing strips of rods. It wouldn't matter which way you bend them, you would never have to worry about 'edge set', as they would always be perpendicular to the moulds.

    Maybe there is a species of grass or bamboo out there ...



    He does talk about his 'core treatment' of the 5mm gap, and 'layup schedule', but I have just been looking through his forums, and it looks like the coating of fibreglass is about as light as any strip planking I have seen. Given that a good glue job never can exceed 50% of the uncut woods strength, the task of the glue between wood strips cant be very onerous.

    Lets face it - every frameless strip plank job relies on the frp to hold it all together.
     
  13. ancient kayaker
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    ancient kayaker aka Terry Haines

    GG is a polyurethane glue, it expends into a foam if it is in a gap or escapes the edge of the joint. Working time is about ½ hour and it sets up enough for handling, if I remember (haven’t used it for a long time) in about 4 hours but needs longer to acquire full strength.


    I have often thought about the rod trick. I think it would be great with some kind of plastic foam that was epoxy compatible. Bamboo isn’t cheap, here at least, or easy to get in the necessary dimensions.


    Not necessarily. I don’t like plastering glass over everything so I have a glued canoe with ribs I have been working on; the ribs provide the crossgrain strength. I like the way it is starting to look, but sanding the inside is a bear. Next time I may try a double cedar boat; build the strip shell first and then glue cedar strips laid crossways on the inside. Again no glass. Not the fastest way to build a boat, but it’s a rare thing these days and a nice little nod to the accomplishments of the great canoe builders in Peterborough, Ontario (Canada) who used to do that back in the 1890's or thereabouts. I think my age is beginning to influence my design decisions . . .
     
  14. ancient kayaker
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    ancient kayaker aka Terry Haines


  15. rwatson
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    rwatson Senior Member

    Yup - thats identical to Purbond.

    Gotcha! ;) Thats why I said :-


    Sometimes, the problems associated with cleaning out the inside of framed boats while building, then become the problems of keeping the frames or ribs clean and mould/water free and the problems of the fasteners holding the ribs on letting in moisture.

    At least with canoes you can usually store them in dry places, unlike larger craft that have to live in the open.

    I have helped maintain traditionally built clinker sailing dinghys that get a lot of use, and all the problems are associated with the dirt and damp accumulating in the voids between ribs and planks, and various other attachments.

    The 'epoxy free brigade' have a case if they are allergic to the stuff, but I would rather spend half the time building, and one fifth the time in maintenance over the life of the boat than be able to claim smugly, it was 'all timber' construction.
     
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