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Thread: Converting sheet plywood to strip planking

  1. #1
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    Default Converting sheet plywood to strip planking

    How reasonable would it be to convert a developable hull design from plywood sheathing to sheathing in strip planking? The hull is fully-framed which is not the usual for strip planking. But the topside and bottom panels, when when presented in a single plane, are somewhat straight linear shapes, requiring little or no side set, which would seem to be easy to duplicate in strip planking.

    I haven't tried strip planking as yet, so it would be a new skill to learn. Handling the strips would seem to be easier than the large plywood panels, and the sheathing could be done in one 1/2" layer rather than two 1/4" layers. Real wood is easier to obtain in Colorado than marine ply. Because no side set would be needed, the strips could be wider, something like 1/2" by 1 1/2". Either way, fiberglass and epoxy would cover the outside.

    Thus far, I have built a 3-foot-long model, easily sheathed in 1/8" ply. At 0.16 scale on the model, the 1/2" thick strips on a full-size hull should be easy to bend.

    https://4.bp.blogspot.com/-s4NTMW1Yb...0/DSC00962.JPG

  2. #2
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    Default Re: Converting sheet plywood to strip planking

    I think it could be done. I planned once to do something like this, as I have poor acess to marine plywood, and made a test-template. You could make the panels flat on a table with strips, and glass it on both sides. That would make a sandviched panel for sheating the hull. It would be important to glass both sides with no delay, to avoid warping.

    You could also check out this reply on an earlyer thread: http://forum.woodenboat.com/showthre...nker-lapstrake Might give you some ideas

    Quote Originally Posted by Gib Etheridge View Post
    Now your talking my language! I've laid up clinker planking out of strips on several boats. You can lay them up right on the boat or make a girder type spiling and lay them up on the bench.

    Here are a couple of pages of photos. You'll notice that there are no frames in this hull. Each plank is glassed inside and out, making them very unlikely to split.

    https://www.flickr.com/photos/48858202@N05/page1

    Laying up with strips allows you to follow the sweep of the plank with the strips, while at the same time allowing you to use narrow stock to your hearts content.

    I've never known anyone else to do it. Welcome to the very small and oh so exclusive (and elite ) club.

    Have at 'er, Bubba!

  3. #3
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    Default Re: Converting sheet plywood to strip planking

    If the panels are developable, you could increase the width of the strips, to say 4 or 6 inches wide.
    That would use a lot less glue.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Converting sheet plywood to strip planking

    Hi,

    this would be glued carvel then ...

  5. #5
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    Default Re: Converting sheet plywood to strip planking

    Quote Originally Posted by W Grabow View Post
    ... Real wood is easier to obtain in Colorado than marine ply. ...
    I know it's not the question you asked but perhaps for others in a search...

    Sears Trostel lumberyard in Fort Collins stocks 4,6,9,12,and 18 mm marine plywood. I purchased 6mm Hydrotek from there.

    Ken

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    Default Re: Converting sheet plywood to strip planking

    Quote Originally Posted by IHWillys View Post
    I know it's not the question you asked but perhaps for others in a search...

    Sears Trostel lumberyard in Fort Collins stocks 4,6,9,12,and 18 mm marine plywood. I purchased 6mm Hydrotek from there.

    Ken
    To pile on Ken's comment, I ordered occume from MacBeath, which has a location in Salt Lake City. My 11 sheets looked scary when it arrived at the Albuq. Truck depot, but was fully usable. If you are in the Denver area that is just one hop from Salt lake, which means shipping is cheaper and your load is less likely to incur forklift damage. -Dan

  7. #7
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    Default Re: Converting sheet plywood to strip planking

    I appreciate the information on Sears Trostel in Fort Collins and MacBeath in SLC. I still have three sheets of 6mm occoume from a previous big order I made from Noah's in Toronto, which would be enough to cover the deck then veneer with mahogany.

    Interesting idea to make sandwiched panels, but I 'm afraid that they would be at least as difficult to handle for placement as full plywood panels.

    Thanks to all for the ideas and information.

  8. #8
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    Default Re: Converting sheet plywood to strip planking

    I would cold mold the hull not strip plank. Actually a cross between cold molding and double diagonal. Two layers 1/4 planks set at 45. Planks can be as wide as you can get, and since the hull is fully developable the planks will go on easy with little spiling. They are also easyer to install than full lenght panels. Plastic staples will make everything a breeze.
    Don't know what wood is available to you but if you choose something that weighs the same as the plywood, weight will stay as per plan.

  9. #9
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    Default Re: Converting sheet plywood to strip planking

    Quote Originally Posted by Rumars View Post
    I would cold mold the hull not strip plank. Actually a cross between cold molding and double diagonal. Two layers 1/4 planks set at 45. Planks can be as wide as you can get, and since the hull is fully developable the planks will go on easy with little spiling. They are also easyer to install than full lenght panels. Plastic staples will make everything a breeze.
    Don't know what wood is available to you but if you choose something that weighs the same as the plywood, weight will stay as per plan.
    I like your idea. If the hull was finished natural, full-length planking would look better, but if painted this would be a nice option. I was thinking of using cypress for the planking which is fairly light-weight and bends easily.

  10. #10
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    Default Re: Converting sheet plywood to strip planking

    You certainly could convert. But why would you? Each has its own advantages, and you are jumping to the labor-intensive, time-consuming, adhesive-intensive ways of strip-planking to make a hull that could more easily be done in sheet goods. And you are building that developable hull... which likely comprosed/simplified in order be buildable with sheet goods and using a technique that WOULD allow you to build something more shapely/sophisticated. My advice is pick one or the other.
    David G
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    Default Re: Converting sheet plywood to strip planking

    + 1

  12. #12
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    Default Re: Converting sheet plywood to strip planking

    Good point, but if you are looking at douglas-fir plywood, you have a choice between checking and glassing. So with DF, you still have the labor-intensive, time-consuming, adhesive-intensive job of covering the fir with glass.

    For a 1/2" thickness, you might want to use more than 6oz glass. The transverse strength of plywood is part of the design, so you need to compensate with the glass.

    Edit:

    Since it is fully framed, the glass is not as much of a factor as it is not needed on the inside. The strength of plywood in the short direction is similar to the long direction where the strips are twice as strong lengthwise and very weak transversely, so the glass is significant on the outside. I understand that a point impact on a flat surface loads the inside in tension, so glass would help more on the inside for impact. There will always be some uncertainty with forum expertise. So if dry wood runs around 10000 psi tensile strength, plywood should be around 5000 psi, and since wood is a mass of defects, working loads run closer to 1000 psi, so maybe 2 layers of 6oz cloth which runs around 300 pli should be enough for 1/2 in thick strip plank panels. Unless it isn't. Correct me as I am wrong. (didn't say if) I know the question, but the answer might need some thought.

    Another opportunity for strip-panels is brightwork. If you want some nice looking topsides, there are possibilities.
    Last edited by MN Dave; 05-11-2017 at 11:18 PM. Reason: last in line, why double up?

  13. #13
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    Default Re: Converting sheet plywood to strip planking

    Quote Originally Posted by W Grabow View Post
    I like your idea. If the hull was finished natural, full-length planking would look better, but if painted this would be a nice option. I was thinking of using cypress for the planking which is fairly light-weight and bends easily.
    How it looks unpainted depends on the design and the viewer. If you want natural finished full lenght planking optics you can always veneer the hull up to the waterline with whatever wood you like. It would involve a lot of work and a lot of maintanance, but it's certainly possible. I would not do it unless I would own a floating boat garage on a lake. Otherwise it's just to much work for me maintaining it, especially in a high UV zone.
    What design are we talking about anyway? A description or link would be nice.

  14. #14
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    Default Re: Converting sheet plywood to strip planking

    I appreciate all the various ideas presented; much more to learn. In the past I have built mainly with plywood, then adding 5-6mm thick planking to give a conventional planked appearance. Strip planking looked like something I might be interested in trying; just to do something different without plywood. I thought that, with good interior framing, the inside probably wouldn't need to be glassed; although I have glassed some bottom areas in the past (between frames) to provide extra strength. Labor-wise, Strip planking (or double diagonal) is more labor intensive, but could be done a section at a time. Plywood, which I do alone, requires that the large panels go up quickly: exact positioning, scarfs, bonding, clamping, temporary staples, clean up, all at high speed. I've seen some beautiful boats with painted bottom and topsides with deck finished bright; which is what I would shoot for. No DF plywood being considered; too stiff, heavy, and hard to sand, plus checking.

    Design-wise, part of my hobby is creating shapely designs that are developable. Below is the location of a image showing a model view from developable-surface-boat-designs.blogspot.com

    https://3.bp.blogspot.com/-PP4iH7HEs...0/DSC00971.JPG

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    Default Re: Converting sheet plywood to strip planking

    Nice boat. To me it looks predestined for double diagonal. If you want you can do the first layer diagonal and the second longitudinal on the topsides, and the bottom double diagonal, your framing looks like it wold allow it. But if you are going to paint it both layers at an angle is easyer, no plank beeing longer then 3 ft. The inside would only need epoxy coating.

    Bowdidge Marine is the only one I know of who strip builds powerboats like this, but he does it over molds, glass inside and ads the framing after.

  16. #16
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    Default Re: Converting sheet plywood to strip planking

    Strip planking works best when in a curve. plywood and lumber work better when used as planking as shown in your choice of boat. unless I'm seeing it wrong you have a shallow vee hard chine hull.
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  17. #17
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    Default Re: Converting sheet plywood to strip planking

    Yes, it is a 14 degree deadrise hard chine hull.

  18. #18
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    Default Re: Converting sheet plywood to strip planking

    Don't do it. See #10

  19. #19
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    Default Re: Converting sheet plywood to strip planking

    Whether you build it from plywood/ glassed over or strip plank glassed over, get rid of most of that framing for starters. Either build it in the traditional way or a modern way. Don't mix the two. Waste of time and money
    Here's a photo of one of our designs that was built a while back. She's the Pro Tournament 26. Note the framework within and how many bulkheads there are. And this is engineered to commercial standards !!



    All glassed in






    Here's the Sea Strike 18.
    Once again, note how many bulkheads/ frames are within the boat. Again..engineered to commercial standards





    Just a suggestion
    Last edited by Mark Bowdidge; 05-14-2017 at 05:09 AM.

  20. #20
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    Default Re: Converting sheet plywood to strip planking

    I was thinking about that in the last few days.
    there's a nutshell thread (I'm nutshell focused at the moment) where the interior is finished bright - it appears to show off a striped hull. Or striped bottom at least.
    ply is beautifully simple and strong, but striped planking gives a lovely looking bright finish.

    Do you have to glass inside and out with strip built?
    if the strips are glued with epoxy maybe not......?
    It's all fun and games until Darth Vader comes.

  21. #21
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    Default Re: Converting sheet plywood to strip planking

    If you check out this link, here we have Jarrett bay boats building game boats from 30 ft up to 90ft. See how they are made from ply/ glass both inside and outside. Note how many bulkheads/ frames there are. AND...these are wooden boats. I guess what I'm trying to get at here is..just because its a wooden boat, doesn't mean we have to use a zillion frames, silicon bronze nails and all that rubbish. We past all that now..its the 21st century. Its just wood, epoxy and glass and we end up with a structure that is equally as strong, if not stronger, but with less weight. Overall this means less Hp, meaning greater efficiency with less fuel consumption
    Check it out
    http://www.jarrettbay.com/carolina-c...ction-gallery/

  22. #22
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    Default Re: Converting sheet plywood to strip planking

    Two reasons I use so many frames: 1) they define the shape of the hull. I don't know how to produce flat panels in the exact shapes I want which could be used for a S&G technique. 6mm plywood can deviate slightly if supports are spaced too far apart. 2) Like studs spaced at 16" centers for a house, I use the frames to support any and all interior pieces- seats, decks, engine controls, battery & fuel tank supports, transom bracing, deck gear, etc. On this model, the frames are grossly over-proportioned for simplicity; its just a model. On a real hull, I can build heavier or lighter frames depending on what their internal function will be.

    Mark, your photos are so outstanding; you make it all look easy.

  23. #23
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    Default Re: Converting sheet plywood to strip planking

    Quote Originally Posted by gypsie View Post
    I was thinking about that in the last few days.
    there's a nutshell thread (I'm nutshell focused at the moment) where the interior is finished bright - it appears to show off a striped hull. Or striped bottom at least.
    ply is beautifully simple and strong, but striped planking gives a lovely looking bright finish.

    Do you have to glass inside and out with strip built?
    if the strips are glued with epoxy maybe not......?
    There is strip built from thin strips held together by glass (usually small boats and conoes) and there is strip built from thick strips held together with edge nails.

    Thin strips held together with glass need glass on the outside and can have either glass on the inside or a lot of frames. This is an example of the frame inside/glassed outside construction: https://adirondack-guide-boat.com/pr...dar-guideboat/

    Thin strips are weak laterally, so they need to be supported on both sides.

    Thick edge nailed strips don't need fiberglass at all.

  24. #24
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    Default Re: Converting sheet plywood to strip planking

    Thick edge nailed strips don't need fiberglass at all.
    Don't agree with this comment at all. Think abrasion. If your out and about and you hit something, your going to dent the strips, even if resin coated. This will then cause all sorts of issues down the track with rot. Even if you glass with with 6oz or similar, at least its some sort of protection. In tropical climates, you've then got the problem with worm eating your hull. Ok if its a trailer boat, however..the faster you go, the more protection you need.
    Mark, your photos are so outstanding; you make it all look easy.
    It is that easy mate LOL

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    Default Re: Converting sheet plywood to strip planking

    Quote Originally Posted by Mark Bowdidge View Post
    Don't agree with this comment at all. Think abrasion. If your out and about and you hit something, your going to dent the strips, even if resin coated. This will then cause all sorts of issues down the track with rot. Even if you glass with with 6oz or similar, at least its some sort of protection. In tropical climates, you've then got the problem with worm eating your hull. Ok if its a trailer boat, however..the faster you go, the more protection you need.

    It is that easy mate LOL
    The need for and problems associated with sheathing are a matter of scale. Your designs are predicated on FRP reinforced wood strip, and it looks like you have it nicely dialed in. The OP seemed to need some feedback as to how much glass is needed on 1/2" (12mm) strips, and I suggested that someone with more experience in this area than myself could recommend the appropriate amount.

    Mr. Smith, I believe, has a much thicker edge nailed or possibly just epoxy bonded strip planked hull that has been coated with epoxy, but not fiberglass. It is in good condition after 30 years, much of it in the tropics. If I am mistaken, Bruce will correct me, again. For worms, the modern equivalent of cascover might be ballistic Nylon, Dynel or polyester coated with a hard, say Shore D 50 PU.
    For additional opinions on sheathing strip planks:
    http://forum.woodenboat.com/showthre...erglass-sheath

    Abrasion:
    http://forum.woodenboat.com/showthre...ion-Resistance
    http://forum.woodenboat.com/showthre...olyester-cloth

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