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Thread: Can real wood replace ply?

  1. #1
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    Default Can real wood replace ply?

    I have used lots of 'marine' ply in repairs and new boats including my current build... but the ply on the market now in no way resembles the ply of 20 years ago, or even 10 years ago. Number of veneers are few, face veneers are paper thin, voids and overlaps abound. Today I cut into a sheet which turned out to have a few square feet of failed glue right in the middle of the sheet... if I was a bit disillusioned before... I am completely over it now.

    So now I'm dreaming of a ply free world. Is it realistic to build without ply? How could, for example, a watertight bulkhead be built from real wood (or at least not ply) without the job becoming an epic project?

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    Default Re: Can real wood replace ply?

    I guess the wikings could give you the best answer.

    I have buildt two (almost) boats using plywood, but having restored a "real wood" lapstrake boat, I now feel that the amount of work and maintance of a "real wood" boat is a bit exagerated. In my lapstrake boat I use boyancy bags because there is no watertight bulkheads. maybe it is possible to make a kind of customized box in shape of a bulkhead t.ex strip planked, and let the rest of the boat be buildt traditional? just a tought, but it needs to be removable in that case,,,

    My next project will be a "real wood" lapstrake build, and it will be interesting to see how much time I will spend compared to the plywood boats. My clinker lapstrake boat lives on a trailer, and she is taking inn some small amount of water when i am sailing, but not so much that it bothers me.

    If you dream about a ply free world, i recomend building a ply free design. In the last issue of Watercreft magazine Paul Gartside have some nice tought asbout this subject, and also a nice and simple real wood design to be buildt.

    What kind of boat are you dreaming about?

    Regards Fred

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    Default Re: Can real wood replace ply?

    In the process of building William Atkin Perigee with epoxy strip plank (see progress at http://geoffboat.weebly.com), but she does have ply bulkheads, deck, and cabinetry.

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    Default Re: Can real wood replace ply?

    No reason why not the watertight bulkheads on our old Danish trawler were effectively tongue and groove, 2" planks with 3/4" strips for the tenons rebated into the planks, a smaller scale system should work equally well.
    https://ich.unesco.org/en/USL/watert...se-junks-00321

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by Small boats rock View Post
    In the process of building William Atkin Perigee with epoxy strip plank (see progress at http://geoffboat.weebly.com), but she does have ply bulkheads, deck, and cabinetry.
    I am impressed, thats a beatiful design!

    I have sometimes considered, and also made a template with, just laying strips down flat, and fabric/glass on each side. If you do that in the recomended thicness, this could replace plywood. I guess the bulkheads have a flat surface,,,


    Fred

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    Default Re: Can real wood replace ply?

    Because most people do not want to pay for guaranteed quality plywood. Get what you pay for. You just need to find a reliable timber dealer who can supply the grade you want. Bruynzeel is as good today as it was 30 years ago......and just as expensive. How many other manufacturers guaranty their boards for 25 years?

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    Default Re: Can real wood replace ply?

    "Is it realistic to build without ply?" - Small boats rock

    Long before there was plywood, there were watertight bulkheads. The problem was that they were a bit complex and a lot heavy. Many of today's small boat designs are predicated on the structural strength and light weight of plywood, and cannot be replicated with solid timber construction. So, you have two choices: either select designs that are intended for solid timber construction and accept the design and weight limitations (and up your game of woodworking skills), or find a source of better plywood.

    Sorry to be blunt, but that is about the shape of the thing.
    Hope for the best, but plan for the worst.

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    Default Re: Can real wood replace ply?

    No matter how it is organized, a large panel must account for expansion/contraction with humidity variation. Plywood solves that problem with alternate cross planking. Solid wood panels usually do it with narrow planks that are individually joined and sealed to allow for the small movement between them. I once built a bulkhead with two layers of edge joined solid wood planks by orienting the layers at 20 degrees to each other. It has lasted for over 35 years as a stable panel but thelong grain edges did need allowance for the normal movement. The 20 degree offset prevented any splitting, allowed essentially identical movement as a single board and made the structure much more stable than a single thickness could.

    All bulkheads since have been of plywood for superior performance, time, cost and effort savings.
    Tom L

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    Default Re: Can real wood replace ply?

    Another point, albeit may be sidelong to your reference to watertight bulkheads; timber/ lumber floats; plywood barely floats.

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

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by Breakaway View Post
    Another point, albeit may be sidelong to your reference to watertight bulkheads; timber/ lumber floats; plywood barely floats.

    Kevin
    Not so - average density of decent ply is (say) about 530 g/m, much the same as solid timber ... which is not surprising considering it is made from timber. And most ply is actually lighter than many boatbuilding timbers.

    The real problem with ply is that there is a lot of cheaper stuff around that often has spurious marks on the boards – after all anyone can stamp BS1088 on a board – it's a British Standard and only enforceable in the UK. If you stick with reliable brands like Bruynzeel, you will get good quality ply; but it is expensive.

    As others have said it's hard to make bulkheads as light as ply – solid timber bulkheads (say tongue and groove boards) are probably going to be 20mm thick, while the equivalent ply bulkhead will be 10mm or 12mm. And it's hard to beat ply for decks and coachroof tops, both structurally and in terms of weight.

    But for hull skins, a cold moulded hull is great. And to a certain extent traditional construction hulls, either clinker or carvel, are not perhaps as difficult as they are reputed to be – though I accept that in very hot climates they are not very suitable for trailer-sailing. One needs also to consider that the majority of traditionally constructed boats are getting on in years now too - so the comparison is not entirely fair.

    I think you have to accept that ply (for boatbuilding anyway) is basically an expensive material if you want a long-lived boat.

    Cheers -- George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

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    Default Re: Can real wood replace ply?

    Plywood is an enormous cost savings over building a wooden panel. Even a top level of ply is cheaper then the materials and labor required to build a panel of equal capability.

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    Default Re: Can real wood replace ply?

    While I agree with you in principle, navydog, we must keep in mind that the majority of folks on this forum are amateur hobbyists, so labour costs are not a consideration. A realistic economic evaluation of any task or project must recognize this. If labour cost is omitted, the panel costs become much closer to equal.
    Hope for the best, but plan for the worst.

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    Default Re: Can real wood replace ply?

    Maybe you should try cold-molding with veneers. You're essentially building your boat out of plywood that is custom-formed to the shape you want. You are in charge of the quality of the plies and how well they are bonded.

    I've never considered it myself because of the high cost of veneer. large amount of epoxy required, and the un-fun work of gluing on the veneers.
    I will beg you for advice, your reply will be concise, and I will listen very nicely and then go out and do exactly what I want! (Apologies to Lerner and Lowe.)

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    Default Re: Can real wood replace ply?

    ^ But the strength-to-weight ratio is wonderful. However, veneer cold-molding of flat panels for bulkheads and superstructures is a bit of overkill.
    Hope for the best, but plan for the worst.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by mmd View Post
    While I agree with you in principle, navydog, we must keep in mind that the majority of folks on this forum are amateur hobbyists, so labour costs are not a consideration. A realistic economic evaluation of any task or project must recognize this. If labour cost is omitted, the panel costs become much closer to equal.
    lol ok, but I figure some people want to finish their boat so they can use it.

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    Default Re: Can real wood replace ply?

    I am by no means a boatbuilder but as a jack of all trades I have noticed that the unmanageable maintainence issue seems to come to traditional wooden boats with age and with too much paint and brightwork.
    The first 10-20 years seem to be rather unproblematic in a Nordic climate if you give the boat a good coat with a mixture of stockholm tar and linseed oil every spring and keep it in a well ventilated boat shed over the winter.

    If I ever get the chance to build a boat I want so use solid wood. Preferably from my own woodland where I have both planking and frames and ribs and gunwales and oars and stem and sternpost growing......... I rekon I could build a good boat ready to launch for less than others pay for the epoxy resin and fiberglass and plywood they need for a build the same size........ but I don't think I ever get the necsessary spare time to do it.
    Amateur living on the western coast of Finland

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    Default Re: Can real wood replace ply?

    The watertight bulkheads in the Harry Bryan designed Thistle I built were made from two layers of 1/4” Cedar epoxied together diagonally. So I guess I made my own 1/2” two ply plywood. Of course it’s just a 12’ double paddle canoe.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by alkorn View Post
    Maybe you should try cold-molding with veneers. You're essentially building your boat out of plywood that is custom-formed to the shape you want. You are in charge of the quality of the plies and how well they are bonded.

    I've never considered it myself because of the high cost of veneer. large amount of epoxy required, and the un-fun work of gluing on the veneers.
    Depending on the size and use of the bulkhead veneers would not be mandatory to construct a panel. A panel could be constructed using narrow (4" or less) 1/4 T&G or ship lap; edge glued and laminated in layers. Vacuum bagging would probably give the best results but other clamping methods are possible.

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    Default Re: Can real wood replace ply?

    Actually, navydog, in Post #15 you have rung the bell at the door of the biggest downfall of amateur boatbuilding - biting off more than what can be chewed. I read a statistic some years ago that said over 50% of all home-built boat projects go uncompleted. Time management - both in estimating the actual time that a project will take, and in maintaining the dedication and drive over a long period of time to complete a boatbuilding project - is the primary reason for not completing the boat. Further, it stated that boatbuilding projects that require two years or more to build have a non-completion rate of around 80%. Even small-ish projects - say a small cruising sailboat estimated at around 2,000 manhours - when translated into an average of three evenings a week plus a full day on weekends (some will protest that they can put in more time than that, but over a couple of years sickness, family commitments, vacations, etc., eat away at the actual hours available to spend on the project) translates into a 23 month job.

    Steven & navydog, there is a size limit to thick-stock laminated bulkheads. Beyond a certain point, the swelling and shrinking of the stock will cause buckling, warping, and cracking. Wood has got to move. Laminating and sealing with epoxy will slow it down, but it will eventually move. This can be accommodated, but it has to be understood, planned for, and built properly.
    Last edited by mmd; 03-02-2018 at 11:45 AM.
    Hope for the best, but plan for the worst.

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    Default Re: Can real wood replace ply?

    I'm thinking that about 4'x4' would be max without problems. Permanently sealing the edges would help a lot.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by mmd View Post
    ....."when translated into an average of three evenings a week plus a full day on weekends (some will protest that they can put in more time than that, but over a couple of years sickness, family commitments, vacations, etc., eat away at the actual hours available to spend on the project) translates into a 23 month job.
    I doubt many amateurs can average 20 hours a week building their boat. Probably more like 8-10 hours, and then all of it is not productive. The moaning chair I have been reading about is not time well spent, even if it's needed. All the more reason to be efficient and effective with time and materials.

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    Default Re: Can real wood replace ply?

    (Post #20) You are probably right, for a bhd that size. That would be in the ballpark for a 17 - 20 ft. trailer-sailer. Bump up to a 24 or 26 ft. boat with standing headroom (think Flicka), and you are flirting with disaster, IMHO.
    Hope for the best, but plan for the worst.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by mmd View Post
    Actually, navydog, in Post #15 you have rung the bell at the door of the biggest downfall of amateur boatbuilding - biting off more than what can be chewed. I read a statistic some years ago that said over 50% of all home-built boat projects go uncompleted. Time management - both in estimating the actual time that a project will take, and in maintaining the dedication and drive over a long period of time to complete a boatbuilding project - is the primary reason for not completing the boat. Further, it stated that boatbuilding projects that require two years or more to build have a non-completion rate of around 80%. Even small-ish projects - say a small cruising sailboat estimated at around 2,000 manhours - when translated into an average of three evenings a week plus a full day on weekends (some will protest that they can put in more time than that, but over a couple of years sickness, family commitments, vacations, etc., eat away at the actual hours available to spend on the project) translates into a 23 month job.

    Steven & navydog, there is a size limit to thick-stock laminated bulkheads. Beyond a certain point, the swelling and shrinking of the stock will cause buckling, warping, and cracking. Wood has got to move. Laminating and sealing with epoxy will slow it down, but it will eventually move. This can be accommodated, but it has to be understood, planned for, and built properly.
    Forum member Suzy J, who was very competently building a Welsford boat (I'm not sure what happened to her), said one of the most true things I've ever read. When complemented on her craftsmanship she claimed she was just stubborn. I think there is a bit of truth to this.

    But she was also very talented!
    Take Care,
    Steve W

    Honeoye Falls, New York
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    A little video of the Suzy J and my youngest son

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    Default Re: Can real wood replace ply?

    FWIW, a couple years ago I replaced the deck on my 19' Ralph Stanley sloop. It was originally two layers of 1/4" ply covered by canvas. I don't like ply for any number of reasons, so I decided to do the job the hard way and laminated the new deck of four layers of 1/8" veneer. I used resorcinol glue and vacuum bagged it, glueing up one layer per bag session. It wasn't as simple as just slapping down some ply, but I was able to use top quality wood and good glue, I know for absolute certain there aren't any voids, and I was able to laminate the four layers with the grain running in three directions, for stability and stress distribution (parallel to keel, 45 off to stbd, 45 off to port, parallel to keel). And yes, I then covered it, as original, in canvas. I built the coachroof the same way.

    Only time will tell if it lasts the same thirty years as the original deck, but I'm pretty confident in it. So I would say that yes, it is definitely realistic to build without plywood.

    Alex

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    Default Re: Can real wood replace ply?

    Realistically once your up to 24' water tight bulkheads are not in the plans for cruising boat, not any Iv'e been around.

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    Default Re: Can real wood replace ply?

    With respect, navydog, there are some. It depends on the design and what the boat is used for, of course.

    Alex, would you be able to tell us how many manhours it took to veneer-laminate the deck?
    Hope for the best, but plan for the worst.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by mmd View Post
    Actually, navydog, in Post #15 you have rung the bell at the door of the biggest downfall of amateur boatbuilding - biting off more than what can be chewed. I read a statistic some years ago that said over 50% of all home-built boat projects go uncompleted. Time management - both in estimating the actual time that a project will take, and in maintaining the dedication and drive over a long period of time to complete a boatbuilding project - is the primary reason for not completing the boat. Further, it stated that boatbuilding projects that require two years or more to build have a non-completion rate of around 80%. Even small-ish projects - say a small cruising sailboat estimated at around 2,000 manhours - when translated into an average of three evenings a week plus a full day on weekends (some will protest that they can put in more time than that, but over a couple of years sickness, family commitments, vacations, etc., eat away at the actual hours available to spend on the project) translates into a 23 month job.
    This is an excellent post! You should copy it over on the "work-to-reward ratio" thread in the "Misc Boat Related" section.

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    Default Re: Can real wood replace ply?

    Feel free to quote me, Dave.
    Hope for the best, but plan for the worst.

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    Default Re: Can real wood replace ply?

    debenriver
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    Re: Can real wood replace ply?

    Originally Posted by Breakaway
    Another point, albeit may be sidelong to your reference to watertight bulkheads; timber/ lumber floats; plywood barely floats.

    Kevin



    Not so - average density of decent ply is (say) about 530 g/m, much the same as solid timber ... which is not surprising considering it is made from timber. And most ply is actually lighter than many boatbuilding timbers.

    The real problem with ply is that there is a lot of cheaper stuff around that often has spurious marks on the boards – after all anyone can stamp BS1088 on a board – it's a British Standard and only enforceable in the UK. If you stick with reliable brands like Bruynzeel, you will get good quality ply; but it is expensive.

    As others have said it's hard to make bulkheads as light as ply – solid timber bulkheads (say tongue and groove boards) are probably going to be 20mm thick, while the equivalent ply bulkhead will be 10mm or 12mm. And it's hard to beat ply for decks and coachroof tops, both structurally and in terms of weight.

    But for hull skins, a cold moulded hull is great. And to a certain extent traditional construction hulls, either clinker or carvel, are not perhaps as difficult as they are reputed to be – though I accept that in very hot climates they are not very suitable for trailer-sailing. One needs also to consider that the majority of traditionally constructed boats are getting on in years now too - so the comparison is not entirely fair.

    I think you have to accept that ply (for boatbuilding anyway) is basically an expensive material if you want a long-lived boat.

    Cheers -- George

    My comment was made based on observation only. I defer to your experience and expertise, George.

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

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by navydog View Post
    Realistically once your up to 24' water tight bulkheads are not in the plans for cruising boat, not any Iv'e been around.
    My 26ft boat from 1964 was built with watertight bulkheads, apparently to confrom with Junior Offshore Group (JOG) racing. I never tried them out, but there was a certain added bit of peace of mind being offshore and seeing so much junk at sea. I would build watertight bulkheads/compartments in any boat i would consider taking offshore, rather than buy a liferaft.......the boat your on is the best bet.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by navydog View Post
    I'm thinking that about 4'x4' would be max without problems. Permanently sealing the edges would help a lot.
    navydog, It would be well to do some study of wood properties. The last several posts show a real lack of fundamental understanding of the subject. I recommend Hoadley's "Understanding Wood" as a source for determining how much a 4' solid wood panel will move across the grain in the normal exposed environment of a boat.
    Tom L

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by Breakaway View Post



    My comment was made based on observation only. I defer to your experience and expertise, George.

    Kevin
    Even more informative to make a basic calculation Kevin. Almost all boatbuilding lumber is heavier than the usual plywood used.

    My comments are not meant to seem like a lecture but rather to encourage individuals to do their homework prior to posting comments that are wrong and may mislead those less informed.
    Last edited by Tom Lathrop; 03-02-2018 at 03:01 PM.
    Tom L

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    Default Re: Can real wood replace ply?

    Well Tom it depends on what species of lumber it's built from doesn't It? After 40 years of working with wood I think I have a pretty good grasp of it's properties.
    Last edited by navydog; 03-02-2018 at 03:21 PM.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by skaraborgcraft View Post
    My 26ft boat from 1964 was built with watertight bulkheads, apparently to confrom with Junior Offshore Group (JOG) racing. I never tried them out, but there was a certain added bit of peace of mind being offshore and seeing so much junk at sea. I would build watertight bulkheads/compartments in any boat i would consider taking offshore, rather than buy a liferaft.......the boat your on is the best bet.
    I can't see how a boat built for Jr racing has much to do with cruising boats I referred to in my comments.

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    Default Re: Can real wood replace ply?

    Quote Originally Posted by Tom Lathrop View Post
    Even more informative to make a basic calculation Kevin. Almost all boatbuilding lumber is heavier than the usual plywood used.

    My comments are not meant to seem like a lecture but rather to encourage individuals to do their homework prior to posting comments that are wrong and may mislead those less informed.
    I think your comparing apple's to oranges Tom. How could Sapele plywood be less dense than a sapele board or doug fir ply less dense than doug fir solid lumber?

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