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Thread: Cosine Wherry

  1. #1
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    Default Cosine Wherry

    In reading "Rip, Strip & Row" , has this boat ever been constructed with tounge & groove strips? In my read, the book does not mention t&g application.

    JLDunn

  2. #2
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    Default Re: Cosine Wherry

    Perhaps no one had thought of T&G for stripping hulls in 1985.
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: Cosine Wherry

    The problem is the strips are not exactly in line with each other. Considering it is wood used in the construction, at many points in the build you would shear off the tongue or the edges of the groove. T&G is suitable for constructing a flat surface, but not a curved surface. I suppose if you milled a lot of slop into your tongues and grooves you could get away with it.

  4. #4
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    Default Re: Cosine Wherry

    The material exists https://www.maritimewoodproducts.com/hull.html . It has been around for quite a while,but you may have to get creative to use it for the entirety of a hull surface.

  5. #5
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    Default Re: Cosine Wherry

    Welcome to the Forum.
    When you say "Tongue and groove" are you referring to traditional T&G as found in home construction or are you referring to strips with 'Bead and cove" as is used instead of square edged stock for strip building such as in the Cosine Wherry? If it's 'bead and cove" then yes you could use that. Bead and cove wasn't in popular use back when that book was written.
    I was born on a wooden boat that I built myself.

  6. #6
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    Default Re: Cosine Wherry

    Quote Originally Posted by Rich Jones View Post
    Welcome to the Forum.
    When you say "Tongue and groove" are you referring to traditional T&G as found in home construction or are you referring to strips with 'Bead and cove" as is used instead of square edged stock for strip building such as in the Cosine Wherry? If it's 'bead and cove" then yes you could use that. Bead and cove wasn't in popular use back when that book was written.
    Bead and cove is midway between square edge and T&G


    As John says stuff like speed strip is one version of T&G, made with enough play to allow for the hull curvature.
    It really is quite difficult to build an ugly wooden boat.

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  7. #7
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    Default Re: Cosine Wherry

    If you can build it with square edge or bead and cove you can build it better with T & G.

    We were building epoxy cold moulded 40'+ hulls with T & G strips in the 1980's for goodness sake – there's nothing new or unusual about it.

    The big advantage of T & G strips is that they run fair and flush to each other better than any other profile, without the feather edge of bead and cove, so the skin stays fair between frames (or moulds) very easily.

    T & G for strip planking is not the same as T & G flooring etc. The fit is slightly looser and shallower and the tongue has a rounded edge, which allows it to rotate slightly in the groove. You generally build with the groove uppermost so the thickened epoxy can be poured into the groove.

    In my experience it's the best strip profile for a cold moulded hull of pretty much any form.

    Cheers -- George
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  8. #8
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    Default Re: Cosine Wherry

    The real problem here is that if you use any form of T and G planking, the material just has to be pretty thick to allow for the machined edges (especially the grooved ones). That is going to lead to a pretty heavy boat, which matters in the case of a 14 foot rowboat, with a target weight of less than 100 pounds if I recall correctly.

    I built my Cosine "workboat tough" (and style) using 2.5 mm plywood, about as thin as it comes, ripped into "planks" over laminated ribs of the same material at each form. Epoxy and FG over the top held things together just fine. Weight is about 70 pounds, which matters when I tow it behind my displacement hull power cruiser, or when rowing. Many years of abuse later, all remains well, no de-lamination or other material problems. The design gets lots of admiration - I could not ask for a better one for my purposes. My latest tweak is to add a self designed drop-in sliding seat, using skateboard components. I should have done this years ago.

    Regards, Tony.

  9. #9
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    Default Re: Cosine Wherry

    Quote Originally Posted by debenriver View Post
    If you can build it with square edge or bead and cove you can build it better with T & G.

    We were building epoxy cold moulded 40'+ hulls with T & G strips in the 1980's for goodness sake – there's nothing new or unusual about it.

    The big advantage of T & G strips is that they run fair and flush to each other better than any other profile, without the feather edge of bead and cove, so the skin stays fair between frames (or moulds) very easily.

    T & G for strip planking is not the same as T & G flooring etc. The fit is slightly looser and shallower and the tongue has a rounded edge, which allows it to rotate slightly in the groove. You generally build with the groove uppermost so the thickened epoxy can be poured into the groove.

    In my experience it's the best strip profile for a cold moulded hull of pretty much any form.

    Cheers -- George
    I get that you could build a 40'+ hull with the special marine version of T&G, but I wonder about doing that on a Cosine Wherry (CW). I suspect the amount of twist and curvature in places on the CW hull is tighter than most any 40' hull, but I could be wrong. The specific commercial T&G product mentioned in #4 indicates that you can have up to a 7 degree difference between any two strips. I am pretty sure there are places in the CW hull where adjacent strips would have a greater difference than that. Also, I am sure you could mill your own T&G, but can you get both the required looseness and the necessary strength in the strip. The CW strips are specified at 1/4" total thickness. If you milled tight fitting T&G, the tongue and each of the groove's shoulders would be 1/12". That seems pretty thin to hold up with any bend at all. As a practical matter, you are probably going to be closer to 1/16" to allow for the difference between two strips. Now, you are talking about very precise milling. I can just see my western red cedar being chewed up by even the best milling tools when trying to get to that thinness. You could use thicker strips for greater strength and ease in milling, but then the weight will increase.

  10. #10
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    Default Re: Cosine Wherry

    What Tony said. The strips are very thin, and you'd have a lot of breakage and failure at the join. Since strip this thin are fairly easy to tape together, I'd just go with the instructions and get on the water. Love my Cosine!



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  11. #11
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    Default Re: Cosine Wherry

    Quote Originally Posted by Tonyr View Post
    The real problem here is that if you use any form of T and G planking, the material just has to be pretty thick to allow for the machined edges (especially the grooved ones). That is going to lead to a pretty heavy boat, which matters in the case of a 14 foot rowboat, with a target weight of less than 100 pounds if I recall correctly.


    Regards, Tony.
    Quote Originally Posted by Thorne View Post
    What Tony said. The strips are very thin, and you'd have a lot of breakage and failure at the join. Since strip this thin are fairly easy to tape together, I'd just go with the instructions and get on the water. Love my Cosine!



    I have seen it used on small tenders to be carried on deck of a high end yacht. So not a problem and a preferred option for a professional boat builder.
    It really is quite difficult to build an ugly wooden boat.

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  12. #12
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    Default Re: Cosine Wherry

    Quote Originally Posted by Tonyr View Post
    The real problem here is that if you use any form of T and G planking, the material just has to be pretty thick to allow for the machined edges (especially the grooved ones). That is going to lead to a pretty heavy boat, which matters in the case of a 14 foot rowboat, with a target weight of less than 100 pounds if I recall correctly.
    That's not quite so. For example Robbins in the UK supplies Cedar T&G strip planking ("Rapid Strip") in 6mm x 22mm, 6mm x 33mm and 6mm x 45mm as standard. The confusion may come from the term Tongue & Groove – the actual profile is more like Bead and Groove:

    tandg.png

    There is really no restriction on the angle between two adjacent strips, but at about 10 the inner side of the bead will start to lift clear of the groove so the advantage of the profile will be lost.

    Many of the builders of my designs machine their own strips, which is relatively simple to do. I specify 6mm on several of the smaller boats 15' - 20', though all will have diagonal veneer layers on top of the strip planking, or bi-axial glass cloth if preferred – but they are all sailboats rather than rowboats, so of more 'robust' construction.

    Cheers -- George
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  13. #13
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    Default Re: Cosine Wherry

    While i was searching for some essential bits and pieces today (and failed to find them),I happened upon a speedstrip sample I picked up at a boatshow several years ago.George's comments are extremely relevant to this thread and I remember his boats from the eighties being the catalyst for me looking into the material.I would expect the 9mm thickness to be about right for a boat the size of a Cosine Wherry.

    speedstrip.jpg

  14. #14
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    Default Re: Cosine Wherry

    As you might have guessed, I'm comitted. I purchased the book from Amazon, PLANS INCLUDED ! However, I'm wondering if I received all of the plans, What I received was two (2) sepia sheets with full size patterns of the transom, stem and all in-between stations. For those of you who have built the boat, were there ever more than just two drawings?

    JLD

  15. #15
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    Default Re: Cosine Wherry

    That's all that came with my book.


    Quote Originally Posted by joedunn View Post
    As you might have guessed, I'm comitted. I purchased the book from Amazon, PLANS INCLUDED ! However, I'm wondering if I received all of the plans, What I received was two (2) sepia sheets with full size patterns of the transom, stem and all in-between stations. For those of you who have built the boat, were there ever more than just two drawings?

    JLD
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

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