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Thread: How to attach Broad plank ti wine glass transom

  1. #1
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    Default How to attach Broad plank ti wine glass transom

    Hello,
    I'm building a Whitehall boat which is lapstrake 14 foot long, 5/16th cedar wood. All of you have been great in helping me thru the build, perhaps you can help me again.

    Question,
    The garboard is on but I am now installing the broad strakes. I am pretty good at steaming but it seems to be a bit of a challenge getting the end of the plank to be as flush as possible across the transom. The bevel is quite steep from the forward part of the transom to the aft part of the transom, along with the fact that the plank is sloping down towards where the next plank will be fitted to it. I have tried to make a mold to compress the tail end of the plank in after it is steamed, and that has helped concave the plank some, but I'm still not touching all of the plank wood to the transom wood.

    I was told you can make a mold called a 'Caul 'or 'Call 'which is something I was trying to do with the little mold I made but I would like to make one that actually works better and know how to use it. I would just love opinions on how to pull this fragile plank into the transom without cracking the board. I actually also backed out a little wood in the underside of the plank to help fit it, but I understand backing out is something you do on carvel boats not lapstrake, so I don't know if this is the right thing to do.

    *It should be noted that that the planks also have a gain that run out to a feathered edge.
    * It should also be noted everything I have done so far is on a sample plank. I didn't want to ruin the broad plank.

    Thanks everyone for your help. Always appreciated
    Mac

  2. #2
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    Default Re: How to attach Broad plank ti wine glass transom

    A few desperate tricks to keep in your back pocket:

    Strip plankers sometimes need to introduce ‘stealer’ strips at ends to handle challenging twists or bends like yours.
    You could cut gores in your plank and let in glued tapered beveled strips. On a 14’ boat, they might be 12-18” long.

    If you’re working from rough stock, leaving one end thick and carving the needed shape might be workable, too. If using a planer, requires nerves of steel to stop at the right time.

    Or maybe you could scarf a thicker piece of stock onto the end of a 5/16” plank and work it from there.
    Last edited by JimConlin; 02-25-2021 at 10:14 PM.

  3. #3
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    Default Re: How to attach Broad plank ti wine glass transom

    Are you trying to curve the board across the grain? Ideally the transom would be a series of flats corresponding to the planks, rather than a true curve. Alternatively you could use thicker stock and back out the curve.

  4. #4
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    Default Re: How to attach Broad plank ti wine glass transom

    A more technical approach would be to lay up the aft 3 feet of the plank with 3 layers of 1/8 in epoxy, right in place so that it's a perfect fit, cold molding on a small scale. Then you would have to join that to the remainder of the plank. Realizing that that particular section of planking will always be prone to splitting I would put 2 oz. cloth between the layers. Tedious, but effective, and it can be done.

    I think I remember that Jim Ledger did just that, minus the glass, on the garboards on his catboat. You could do much much worse than follow his lead.

  5. #5
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    Default Re: How to attach Broad plank ti wine glass transom

    Another question, what type of gain are you using in the plank lap? From your wording it kind of sounds like you don't have a gain cut.

  6. #6
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    Default Re: How to attach Broad plank ti wine glass transom

    Just to add in my limited experience, keep the strake a good bit longer as you can steam a sharp bend in before you cut, but can never do it if you only have a few inches over the transom

  7. #7
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    Default Re: How to attach Broad plank ti wine glass transom


  8. #8
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    Default Re: How to attach Broad plank ti wine glass transom

    Thank you everyone for your responses. I will address some of the questions you asked me.

    1)There is a gain that is 18 inches long that runs out to a feathered edge on the transom. It is 5/8 width.
    2)The curve of the plank runs witdth wise across the grain of the plank. Keep in mind it is 5/16th WRC. the plank at the point of contact with the transom is approx.2.5 inches across. The gain takes up 5/8ths of the 2.5 inches.
    3) I have left approx. 6" as tail on the plank on the aft side of the transom.

    Q) Jim you mentioned 'Cut Gores ' and ' Let in glued tapered strips '. A little confused on what that all means. If you have time for a little more explanation it would be helpful as the terms leave me wondering exactly what you meant.

    Q) I did notice' no' one mentioned anything about making a small mold that mimics the concave curve of that part of the transom where the tail end of the plank is to land. The plank end would be steamed and then compressed in the mold for perhaps an hour and then with any luck anchored. is this a method that you have not heard of or is problematic ?

    Q) Is it common 'IF' needed to backout some of the plank to help make the plank shape more concave to fit the the curve of the transom? If I'm not mistaken it sounds more common to add wood or layered epoxy and then work it down until if fits the bevel and curve of the transom.

    Q) Lastly, I can be a good cobbler of things but in my endeavor to build boats ( this being the the third and most difficult ) I am trying to go slow and be patient and do a good job. Certainly not museum work but acceptable for a beginner. That being said do you sometimes just have to find a way to make it work, even it is not AAA quality work.

    All your comments are appreciated.
    Thx Mac

  9. #9
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    Default Re: How to attach Broad plank ti wine glass transom

    Might have answered your own question with a simple clamping 'mold' that gives some shape across the grain. My HV's have a faint winglass, you probably have more. I have a very slight hollow along the garboard and broad but the planks push in well enough without extraordinary measures. The convex curve of the transom is faceted as I plank up, as J Madison suggests. In the end, I mask a fair curve around the transom for the hull paint. But I'm not looking at your transom ...

    Note - the 'faceting' is focused on the outboard edge as you plank up.
    Last edited by Eric Hvalsoe; 02-26-2021 at 08:45 PM.

  10. #10
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    Default Re: How to attach Broad plank ti wine glass transom

    Quote Originally Posted by Mackey View Post
    Q) Jim you mentioned 'Cut Gores ' and ' Let in glued tapered strips '. A little confused on what that all means. If you have time for a little more explanation it would be helpful as the terms leave me wondering exactly what you meant.


    I'm taking Jim's suggestion to mean cutting grain-wise grooves into your plank(s) such that the material removed serves to allow the inside face to remain intact as the grooves are later filled with tapered splines, then the curve desired formed capturing those splines as the grooves (gores?) are closed. Done with care then scraped smooth once the glue's clicked the result should be both sturdy as well as appropriate for a nice paint-finished outer hull.



    I've made stage sets in this manner where moulded trim had to be curved. Once the gores are cut the moulding becomes quite bendy, the gores later filled with plaster... but this is stage stuff, cross0-grained moulding & not a boat's planking.



    Quote Originally Posted by Mackey View Post
    Q) I did notice' no' one mentioned anything about making a small mold that mimics the concave curve of that part of the transom where the tail end of the plank is to land. The plank end would be steamed and then compressed in the mold for perhaps an hour and then with any luck anchored. is this a method that you have not heard of or is problematic ?


    That's how I'd approach it m'self. Did a furniture piece for a friend 40 years ago that had radiused corners in the cabinet frame. I sawed veneer out of basswood, made cauls from particle board that served to laminate the veneer into the shape I wanted. Once I'd made four the edges were rabbeted to take the end panels & frames, then entire outer surface covered in (sigh...) high pressure laminate.



    With care and some practice your 5/16" WRC ought to respond similarly once softened up (soak well first before steaming) prior to being clamped in your cauls ("NOUN - 1) (woodworking) A strip or block of wood used to distribute or direct clamping force.") then allowed to dry for a day or two under pressure. Best not to epoxify wood that's at all wet unless the stuff is labeled as such.



    Quote Originally Posted by Mackey View Post
    Q) Is it common 'IF' needed to backout some of the plank to help make the plank shape more concave to fit the the curve of the transom? If I'm not mistaken it sounds more common to add wood or layered epoxy and then work it down until if fits the bevel and curve of the transom.


    That'd be a proper way to achieve a workmanlike result AS LONG ASthick enough to give you the material for backing out. Needs to be done to both faces it does; concave on the outside, convex on the side to meet the transom. Not necessary for all the planks either, just those needing to conform to the recurved transom.



    Might be the best way to avoid any persistent stresses in those planks too, the wood's not being tortured, just sculpted to fit the need.
    Last edited by sp_clark; 02-26-2021 at 09:11 PM.

  11. #11
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    Default Re: How to attach Broad plank ti wine glass transom

    Quote Originally Posted by lexi View Post
    Just to add in my limited experience, keep the strake a good bit longer as you can steam a sharp bend in before you cut, but can never do it if you only have a few inches over the transom
    'Zactly.

  12. #12
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    Default Re: How to attach Broad plank ti wine glass transom

    Back it out. That's how it's been done, traditionally you make sure you still have the proper plank thickness but run whatcha brung. It ain't cheating if it works. Sure you can do all the other methods but they are not traditional.

  13. #13
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    Default Re: How to attach Broad plank ti wine glass transom

    Walt Simmons addresses this in his book "Lapstrake Boatbuilding Volume 2" (pages 74-75 in my copy). He changes the setting on his thickness planer as the board goes through, ending up with a 1/2" plank tapering to 3/4" at the transom end. He tapers on both sides of the plank. Then he hollows the inside and rounds off the outside of the plank to match the tuck.

    This is a shortened version of what he writes but gives the gist of it.

    Jamie

  14. #14
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    Default Re: How to attach Broad plank ti wine glass transom

    Quote Originally Posted by Jamie Orr View Post
    Walt Simmons addresses this in his book "Lapstrake Boatbuilding Volume 2" (pages 74-75 in my copy). He changes the setting on his thickness planer as the board goes through, ending up with a 1/2" plank tapering to 3/4" at the transom end. He tapers on both sides of the plank. Then he hollows the inside and rounds off the outside of the plank to match the tuck.
    I've done similar (but not for planking) on a jointer, it can be done as long as you pay attention to where you're at along each plank.

    And take shallow cuts once you get the bulk of what you want to remove off.

    I changed that bit about both sides to bold to call attention to the fact that using a thickness planer demands doing the taper to both sides... otherwise the planer''ll just do what it's designed to do, i.e shave your plank flat.

  15. #15
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    Default Re: How to attach Broad plank ti wine glass transom

    Not sure my Thank you to you guys has gone through. One more time. Thanks for the help.
    Mac

  16. #16
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    Default Re: How to attach Broad plank ti wine glass transom

    This is an issue with a couple of the whitehalls I build. Both down in the tuck and the up at the shear you get some extreme cross grain shape. You can attempt to steam the shape in but its often touchy, and frequently will split when fastened. Better is to either taper the entire raw plank on a planer, or scarf in a thicker section that allows the shape to be carved...be warned the gains get extra tricky to keep fair and rolling. For lapstrake boats it is more stock efficient to just taper a piece for the last few feet and the scarf that on.

    I taper planks all the time, mostly in carvel construction. I cant see any reason to do both sides...in fact I would imagine it being very difficult to keep things smooth and fair. It's really quite easy. You start by planing the stock to the required max thickness (planking thickness plus amount of max curve). Then you mark/write out other thickness required at each station (they will all differ) on the plank's face where you can read it. Experiment with your planer to discover what one full revolution of the adjustment wheel equals. Then just feed it in and adjust gradually smoothly as the plank feeds, paying attention to where your at and where you going. If you have a lot of taper it may take a few cycles through to get there. Once you get things close, use a marking gauge from the flat true side (usually the inside) to scribe the final thickness on each plank edge (5/16 in your case)... now you can fair and carve the plank. Do your hollows first then flip and carve your rounds. Gains at the end, I like to steam any twist in before i cut gains. When you do cut the gains, it requires some creative wedging and clamping to support the workpiece on the bench.

  17. #17
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    Default Re: How to attach Broad plank ti wine glass transom

    I should add, that if the twist is significant enough to require steam, make sure you scarf in a piece long enough to avoid steaming the scarf

    when putting in strong hollow, keep the flat reference face on the "outside", when putting in round the reference face is the "inside". when a plank goes from round to hollow...it gets harder.
    Last edited by windfall; 02-28-2021 at 08:30 PM.

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