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Thread: Ply v dimensional plank for hull

  1. #1
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    Default Ply v dimensional plank for hull

    I am building a 16 ft Wherry and am starting on the hull. I am dissatisfied with the quality of Douglas fir plywood available from local lumber yards (real suppliers not big box) that have in the past have been reliable for quality and availability. Reasons Iíve been told for this supply and quality decrease range from fires in the West to the commoditization of the supply chain.

    Because I canít find quality plywood Iím going to build the lapstrake hull from cypress planks instead. My question on this topic: What thickness of planking will be necessary to equal 9 mm ply in substitution for equal strength and durability?

  2. #2
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    Default Re: Ply v dimensional plank for hull

    As far as I know in most cases you can't just simply substitute real wood planks for ply. There are a gazillion plans for solid wood boats, and I have one that I restored and have been actively sailing for over 12 years, so why not build one the easy way -- to plans for the materials you want to use? There are a few plans that cover both materials, and if you're experienced with building you can convert some ply designs to solid wood (but not all), but it seems like a lot of trouble just to save money on plans.

    Alternately just order Occume or Meranti marine ply -- much better quality than DF marine ply, and it doesn't have to be glassed on both sides to avoid checking and splitting as DF ply does, resulting in a lighter, more responsive boat. That way you can build the boat you want using your current plans.
    Last edited by Thorne; 04-30-2019 at 04:13 PM.
    "The enemies of reason have a certain blind look."
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  3. #3
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    Default Re: Ply v dimensional plank for hull

    What design is it? Many glued lap boats are perfectly capable of being built in traditional lapstrake instead. Have you talked to the designer? Reaching out to them and telling them what you want to do would be your best bet. Aside from the planking change, you’ll be adding frames every six inches or so.
    -Jim

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    Default Re: Ply v dimensional plank for hull

    The planks don't offer the cross-grain strength and resistance to splitting that ply offers. Get plans for a traditional wherry. Talk to the designer, or check John Gardners books, as he published plans for a traditionally built wherry or two.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  5. #5
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    Default Re: Ply v dimensional plank for hull

    OTOH, Iain Oughtred generally recommends ply/epoxy construction of his boats, but also includes- at least with the Penny Fee plans I purchased from him- a materials list for "traditional construction."
    For ply/epoxy construction the plans call for 9mm (3/8") ocume for planking, and for traditional construction 1/2" planking- the species he says is largely dependent upon availability, but mentions larch, fir, spruce, SWP, Oregon pine, maybe others...
    pvg

  6. #6
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    Default Re: Ply v dimensional plank for hull

    Spoke to designer. This is a Wherry designed by Walt Simmons, ducktrap.com
    7/16 Planking can be substituted for 9 mm ply. Ribs at stations and roves, burrs and rivets instead of epoxy. Weight not significantly different from ply/epoxy construction.

    He too lamented the state of the wood supply business and the difficulty of finding quality ply suitable for boat building at any price today.

    So........ planking it is. Probably the entire boat will be Cypress.

    Do builders in the rest of the country and abroad have similar ply supply problems?

  7. #7
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    Default Re: Ply v dimensional plank for hull

    Cypress is a good choice. The only marine ply that’s available to me is the Doug Fir variety. But I prefer build with solid lumber anyway. Good luck on your project.
    -Jim

    Sucker for a pretty face.
    1934 27' Blanchard Cuiser ~ Amazon, Ex. Emalu
    19'6" Caledonia Yawl ~ Sparrow

    Getting into trouble one board at a time.

  8. #8
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    Default Re: Ply v dimensional plank for hull

    Builders in areas with no local supply of Occume or Meranti marine ply often order it to be shipped to them or drive to pick it up, and sometimes combine orders with other builders to save shipping or fuel costs.

    I'm sure you'll enjoy building with solid wood, and the result will be very traditional. My fir over oak dory skiff needs to be pre-soaked before trailered to the water and launched, and even after that will make a bit of water. Your trailer should be as lightly sprung as possible, as solid wood boats don't respond well to being bounced around on the usual over-sprung boat trailers with 2-ton springs designed for heavy fiberglass boats.
    Last edited by Thorne; 05-02-2019 at 10:17 AM.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  9. #9
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    Default Re: Ply v dimensional plank for hull

    The Doug fir ply I was able to obtain I suppose was good enough for cabinet backs or interior paneling that’s about it.
    Voids, cracks, splits. Often splintered and cracked when trying to use it for planking on hull. Definitely not suitable for boatbuilding and taking out on the ocean.

    Okoume when it’s available last quote $132/9 mm sheet. 18 mm N of $200. Order soon the price is going up.
    At that price it becomes cheaper to buy dimensional lumber and mill it yourself.

  10. #10
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    Default Re: Ply v dimensional plank for hull

    It is not cheap to build a wooden boat.

    I would still stress building with ply. but
    not fir.

    I'd make the trip/effort to obtain marine ply. CLC in Annapolis is a very very good source.

    Most if not all boats being built nowadays are going to be out of the water way, way, more then in the water.

    Planks will dry, and all the non-fun that comes along with movement.
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  11. #11
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    Default Re: Ply v dimensional plank for hull

    With the supply, quality, price and import problems with okoume, noted in other threads in this forum and related to me personally by suppliers, I wonder how CLC and other kit builders are going to deal with this problem. Do they have warehouses stuffed with inventory, or smart enough and have the cash/credit to take large forward contracts on the product?
    Forward contracts are worthless if you can’t get the product past customs. This would create whole other financial problems for contract holders.

  12. #12
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    Default

    Your building one boat, if the cost even doubles on plywood, it's still going to last longer than wood drying and swelling in storage over the years.


    Sent from my LG-M430 using Tapatalk
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  13. #13
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    Default Re: Ply v dimensional plank for hull

    Denise: I was remarking on the boat in a box kit market which CLC and others serve. I imagine this market is quite price sensitive. Doubling the price of the kit would probably cut demand for kits significantly, hitting the bottom line of the kit builders hard. Those CNC machines ain’t cheap!

  14. #14
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    Default Re: Ply v dimensional plank for hull

    Quote Originally Posted by Arlc View Post
    Spoke to designer. This is a Wherry designed by Walt Simmons, ducktrap.com
    7/16 Planking can be substituted for 9 mm ply. Ribs at stations and roves, burrs and rivets instead of epoxy. Weight not significantly different from ply/epoxy construction.

    He too lamented the state of the wood supply business and the difficulty of finding quality ply suitable for boat building at any price today.

    So........ planking it is. Probably the entire boat will be Cypress.

    Do builders in the rest of the country and abroad have similar ply supply problems?
    Any amount of good plywood available here, most comes from Indonesia, Maylasia or the Phillipines, renewable plantations of Meranti and Okume are coming on line, pretty ok quality. You get what you pay for, and I find that its worth paying a little more to get product that makes a good boat.

    John Welsford
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  15. #15
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    Default Re: Ply v dimensional plank for hull

    I hope I'm not hijacking the thread, but I'm planning a similar project and am asking for a bit more detail.

    I, too, am planning to build a boat, a Whitehall, from the plans in John Gardner's book. Cypress seems to be the best local wood. And I would expect this boat to spend most of it's life on dry land, here in New Orleans, waiting to be used.

    Mr Gardner writes that Whitehalls are traditionally carvel planked, save perhaps the sheerstrake and possibly even the strake below that.

    Am I pursuing an unwise choice in making these plans? Are plywood planks and strakes always better than solid lumber for a boat that lives on a trailer?

    Is there any way to make lumber a feasible application?

  16. #16
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    Default Re: Ply v dimensional plank for hull

    Quote Originally Posted by chollapete View Post
    I hope I'm not hijacking the thread, but I'm planning a similar project and am asking for a bit more detail.

    I, too, am planning to build a boat, a Whitehall, from the plans in John Gardner's book. Cypress seems to be the best local wood. And I would expect this boat to spend most of it's life on dry land, here in New Orleans, waiting to be used.

    Mr Gardner writes that Whitehalls are traditionally carvel planked, save perhaps the sheerstrake and possibly even the strake below that.

    Am I pursuing an unwise choice in making these plans? Are plywood planks and strakes always better than solid lumber for a boat that lives on a trailer?

    Is there any way to make lumber a feasible application?
    Carvel planking for a boat that's going to live out of the water? It will need time to soak up each time you launch it.

  17. #17
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    Default Re: Ply v dimensional plank for hull

    Quote Originally Posted by john welsford View Post
    Any amount of good plywood available here, most comes from Indonesia, Maylasia or the Phillipines, renewable plantations of Meranti and Okume are coming on line, pretty ok quality. You get what you pay for, and I find that its worth paying a little more to get product that makes a good boat.

    John Welsford
    What price do you pay for quality ply in your neck of the woods?

  18. #18
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    Default Re: Ply v dimensional plank for hull

    Quote Originally Posted by chollapete View Post
    I hope I'm not hijacking the thread, but I'm planning a similar project and am asking for a bit more detail.

    I, too, am planning to build a boat, a Whitehall, from the plans in John Gardner's book. Cypress seems to be the best local wood. And I would expect this boat to spend most of it's life on dry land, here in New Orleans, waiting to be used.

    Mr Gardner writes that Whitehalls are traditionally carvel planked, save perhaps the sheerstrake and possibly even the strake below that.

    Am I pursuing an unwise choice in making these plans? Are plywood planks and strakes always better than solid lumber for a boat that lives on a trailer?

    Is there any way to make lumber a feasible application?
    A couple of things you can do that will help are;

    Use vertical grain lumber for the planking. It will do most of it's shrinking and swelling thickness wise. If you build with very well air dried lumber and bed the laps and garboard to keel joints in Sika 251 then seal it very well with epoxy and paint and store it under cover you may not have any problems at all.

    For added protection you can fiberglass each plank inside and out with 4 oz. cloth in epoxy. If you do that you can lessen the thickness a bit thereby compensating for some of the added weight. Glassing the faces stiffens the planks considerably and makes them far less likely to split.

    If you like varnishing you can apply and maintain enough coats to protect the epoxy from UV, but paint will do that better. A good compromise would be bright sheer planks and paint the rest. Dry fit the plank, remove it and over bend it to approximate shape plus some on the bench then glass the inner face. Flip it and glass the outer face. Make sure to glass the bevels, that way they won't split if it does ever move some. Paint the inner face before applying the plank to the hull, that way you have sealed and protected under the ribs. I built a clinker 21 foot double ender with no frames at all by glassing each plank inside and out with 6 oz. No problems at all, ever.

  19. #19
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    Default Re: Ply v dimensional plank for hull

    Quote Originally Posted by Arlc View Post
    With the supply, quality, price and import problems with okoume, noted in other threads in this forum and related to me personally by suppliers, I wonder how CLC and other kit builders are going to deal with this problem. Do they have warehouses stuffed with inventory, or smart enough and have the cash/credit to take large forward contracts on the product?
    Forward contracts are worthless if you can’t get the product past customs. This would create whole other financial problems for contract holders.
    Someone needs to manufacture 100% WRC ply to BS 1088 or BS6566 specs right here in N. America, or with Spanish cedar to the same specs down in S. America. It would be about as light as Okoume and much less prone to rot. Best of all would be if the veneers were VG.

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