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Thread: Attaching planks to seat tanks

  1. #1
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    Default Attaching planks to seat tanks

    I've made some pretty good progress on the Campion Apple build, but I'm not sure how to proceed with the next step. I've built my own 'custom' interior arrangement and have strayed from the original plans with the designer's approval, but now I'm in the details and I need some advice. I've installed watertight seat tanks along each side and a rear deck with a semi-watertight compartment. I could just paint it all and call it a day, but I'd like to install planks on top of the side tanks and rear deck. My plan is to finish them with something like Deks (satin).

    My current plan is to epoxy 3/8" stringers to the tops of the seat tanks oriented side to side and then screw the planks to those so they would be not sitting flat on the seat tanks (see my terrible drawing below). My thinking is that if I screw them directly to the seat tanks, water will get into the cracks and just sit and fester, while if I allow the water to flow under them I'm not inviting rot.

    In either case, I would like to have them removable for refinishing or replacement down the line.

    Any thoughts on this approach or am I just overthinking it and just screw them down?

    Here is a bad depiction of what I want to do (nobody ever accused me of being an artist). The red lines indicate 3/8" stringers epoxied to top of seat tank:


    Roughed planks:

  2. #2
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    Default Re: Attaching planks to seat tanks

    Before I read as far as your idea I was thinking to myself " just glue some "cleats" (not called stringers) to the top of the tanks". That is what I would do.

  3. #3
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    Default Re: Attaching planks to seat tanks

    Thank you; 'Cleats', that's the word. I am terrible with terms and I'm pretty new to building wood boats so I am constantly struggling to communicate. Is the use of cleats a standard approach for this sort of arrangement?

  4. #4
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    Default Re: Attaching planks to seat tanks

    Seems to me creating some semi-permanent dead air spaces that can also entrap water can't be good. But not at all sure how I'd do this. Or if . . .

  5. #5
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    Default Re: Attaching planks to seat tanks

    Quote Originally Posted by Ian McColgin View Post
    Seems to me creating some semi-permanent dead air spaces that can also entrap water can't be good. But not at all sure how I'd do this. Or if . . .
    I hadn't thought there would be dead air space underneath, it will be open on the inboard and outboard sides and there will be a gap in between the planks, but I'm definitely open to other suggestions/methods.

  6. #6
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    Default Re: Attaching planks to seat tanks

    A suggestion, for what it's worth: Fasten the cleats to the seat boards but not to the floatation tanks, and secure the resulting seat assembly with toggles or similar mechanism that is easy to undo. For example you could put another cleat in the hull side (aligned fore and aft) and positioned so that the seat would slide under it, which would hold down the back of the seat. Then a simple toggle could be fashioned to hold down the front edge. Or a bungee loop, or whatever other approach suits the nature of the boat from many possibilities. That way the seat itself is removable as a single piece for cleaning and refinishing and you can also arrange any fasteners going into the tanks so that they are not on a horizontal surface.

    Also I think 3/8" is too thin for this purpose? Not a lot of wood to fasten into there. (Other people with more experience than I may weigh in here with a different opinion however).

    And finally another term for you: What you refer to as "side to side" is properly called "athwartships" on a boat. Easy to remember because thwarts run athwartships...

    ETA: All this is assuming that you are creating seats with multiple planks that need to be held together with a cleat. I can't see the photo of the planks but if each seat is a single piece then I would use the cleat-and-toggle to hold it down with no athwartships cleats at all. Also I note that my use of the term "cleat" in two different ways here may be confusing. I'll try to post a drawing later if you are interested - let me know.
    Last edited by cstevens; 07-27-2017 at 09:46 AM.
    - Chris

    Life is short. Go boating now!

  7. #7
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    Default Re: Attaching planks to seat tanks

    I must say.. that is one BEAUTIFUL http://www.fernhollow.net BOAT!
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  8. #8
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    Default Re: Attaching planks to seat tanks

    Quote Originally Posted by cstevens View Post
    A suggestion, for what it's worth: Fasten the cleats to the seat boards but not to the floatation tanks, and secure the resulting seat assembly with toggles or similar mechanism that is easy to undo. For example you could put another cleat in the hull side (aligned fore and aft) and positioned so that the seat would slide under it, which would hold down the back of the seat. Then a simple toggle could be fashioned to hold down the front edge. Or a bungee loop, or whatever other approach suits the nature of the boat from many possibilities. That way the seat itself is removable as a single piece for cleaning and refinishing and you can also arrange any fasteners going into the tanks so that they are not on a horizontal surface.

    Also I think 3/8" is too thin for this purpose? Not a lot of wood to fasten into there. (Other people with more experience than I may weigh in here with a different opinion however).

    And finally another term for you: What you refer to as "side to side" is properly called "athwartships" on a boat. Easy to remember because thwarts run athwartships...

    ETA: All this is assuming that you are creating seats with multiple planks that need to be held together with a cleat. I can't see the photo of the planks but if each seat is a single piece then I would use the cleat-and-toggle to hold it down with no athwartships cleats at all. Also I note that my use of the term "cleat" in two different ways here may be confusing. I'll try to post a drawing later if you are interested - let me know.
    Chris, I like the idea, and had considered some sort of toggle to hold them down, but because there is a slight curve running fore and aft, I need to bend the planks into position and I'm not sure I could make something robust enough to hold them in place.
    You may be right on the 3/8", it might not provide enough bite. I'll have to rethink that.

    My problem with terminology is that while I may know and understand many of the terms, recalling them can be a problem for me. Clearly, I have work to do.

    Thank you.

  9. #9
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    Default Re: Attaching planks to seat tanks

    Quote Originally Posted by DeniseO30 View Post
    I must say.. that is one BEAUTIFUL http://www.fernhollow.net BOAT!
    Thanks Denise,
    I really like the lines and I hope that the designer won't disavow any knowledge of it when I'm finished. It certainly won't be perfect, but I'm pretty happy with how things are turning out.

  10. #10
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    Default Re: Attaching planks to seat tanks

    Credit given where credit due! Looking at the boat and your build it looks like all those boxes are made for flotation first storage second. It also seems a shame to not have some of them with opening lids. That could work but it would mean airtight seals or air bags inside the boxes, I'll call them lazarettes
    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: Attaching planks to seat tanks

    Quote Originally Posted by galleywench View Post
    Chris, I like the idea, and had considered some sort of toggle to hold them down, but because there is a slight curve running fore and aft, I need to bend the planks into position and I'm not sure I could make something robust enough to hold them in place.
    You may be right on the 3/8", it might not provide enough bite. I'll have to rethink that.

    My problem with terminology is that while I may know and understand many of the terms, recalling them can be a problem for me. Clearly, I have work to do.

    Thank you.

    Ah - now I see the photos on your blog. As Denise says, that's going to be a lovely boat! And no worries on the terms. It's handy to use the appropriate nautical word for clarity, but we can also get hung up on the pedantry of it all sometimes. My grandfather, the late Capt. R. S. Stevens jr. USN (Ret.), was a prime example. "It's not a dock" he would exclaim whenever someone used that word as a noun. "It's a pier. Dock is a verb! You dock a ship at a pier!". And he was absolutely not to be argued with. At any time. On any subject. Quite the naval officer was my grandfather, even well after retirement.

    But I digress. I see the problem of holding your seats down if the tops of the tanks are not flat. A couple of thoughts come to mind. One is that you could use the athwartships cleats to hold the planks together and also to adjust for the curve by making them deeper in the center than on the ends. The other is that using the cleat-and-toggle design that I'm envisioning would let you spring the planks in place and hold them down. If the curve is fairly gentle then that should be doable, although in that case you would want a wooden toggle to hold the front down, not a bungee loop of course.

    All of these techniques, by the way, are typical approaches to making and securing floorboards in traditional small craft - Whitehalls and the like. So you might look at some of those boats for inspiration as well. They have basically the same problem - how to create a (somewhat) flat surface on top of a curved structure that will be removable and will not trap water. There have been a few threads on that subject here in the past.
    - Chris

    Life is short. Go boating now!

  12. #12
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    Default Re: Attaching planks to seat tanks

    Something like this perhaps:



    I can imagine modifications to further locate the seat on top of the tank but I suspect that since they would be captured by the frames, the hold-down cleats and the bungee loops they would stay in place in anything less than a full inversion, and maybe even then. You could also situate the hold-down cleats on the frames rather than the hull, which might be an elegant solution for those. Perhaps with a slight angle to make insertion of the seats easier, which would be a nice touch as well. And if you don't like the idea of a bungee loop you could use a rotating wooden button or toggle to hold down the front edge although that would be a bit more work. Not much in comparison to the full project though!
    - Chris

    Life is short. Go boating now!

  13. #13
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    Default Re: Attaching planks to seat tanks

    Credit given where credit due! Looking at the boat and your build it looks like all those boxes are made for flotation first storage second. It also seems a shame to not have some of them with opening lids. That could work but it would mean airtight seals or air bags inside the boxes, I'll call them lazarettes
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  14. #14
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    Default Re: Attaching planks to seat tanks

    This is our set up on "Bright Star". For lazy sailing we have a set of cushions that fit over them. The seating hatches are attached with bronze piano hinges.
    Jay
    Last edited by Jay Greer; 07-29-2017 at 09:29 AM.

  15. #15
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    Default Re: Attaching planks to seat tanks

    Quote Originally Posted by cstevens View Post
    Something like this perhaps:



    I can imagine modifications to further locate the seat on top of the tank but I suspect that since they would be captured by the frames, the hold-down cleats and the bungee loops they would stay in place in anything less than a full inversion, and maybe even then. You could also situate the hold-down cleats on the frames rather than the hull, which might be an elegant solution for those. Perhaps with a slight angle to make insertion of the seats easier, which would be a nice touch as well. And if you don't like the idea of a bungee loop you could use a rotating wooden button or toggle to hold down the front edge although that would be a bit more work. Not much in comparison to the full project though!
    That looks like a great solution, I like the idea of not needing to screw the planks into the tanks. I'm going to have to spend some quality time with the boat and several beers to work this out in my head, I think it might work.

  16. #16
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    Default Re: Attaching planks to seat tanks

    So I started working out the details that Chris suggested and I think I can do it using several captive nuts or t-nuts embedded in the tanks to hold the seats down, but once I screwed the cleats to the planks, and got everything clamped into the basic position, I'm not 100% sure I like the look... Take a look and give me your opinions. It's obviously not finished, but do you think the visible cleats will disrupt the look of the interior? Maybe I'm just overthinking the whole thing and should just screw the planks into the tanks directly without any cleats to drain water? Thoughts?


  17. #17
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    Default Re: Attaching planks to seat tanks

    Pictures aren't showing for me...
    - Chris

    Life is short. Go boating now!

  18. #18
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    Default Re: Attaching planks to seat tanks

    Quote Originally Posted by cstevens View Post
    Pictures aren't showing for me...
    Lets try that again...


  19. #19
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    Default Re: Attaching planks to seat tanks

    I see now. Hmm. I like the look myself but it's hard to say because I don't know how the boat will be finished. I was envisioning individual slats somewhat like this:



    Maybe extending past the edge of the tanks a bit, with a bullnose to finish the edge? But if that doesn't fit the overall aesthetic you have in mind then perhaps another solution would be better.

    I wouldn't want to fasten the planks directly to the top of the tanks without some way to remove them for cleaning and refinishing. And I wouldn't want to make holes all the way through the top of the tanks either (which I assume was the point of your original design for the fixed cleats as well). You could eliminate the cleats by making the seats out of plywood and full-width with a hardwood edge to cover the end grain. That way they could still be made removable but would sit directly on top of the tanks.
    - Chris

    Life is short. Go boating now!

  20. #20
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    Default Re: Attaching planks to seat tanks

    As much as I liked the removable "seats and cleats" plan, my implementation fell short. The curve in the fore and aft direction required quite a bit of force to bend in place and the whole arrangement just felt 'cobbled'. I'm sure someone with a better skill set and more experience would find this project a no-brainer, but I have to accept my shortcomings and move on. In the end I decided to glue the cleats in place on top of the seat tanks and ordered some stainless steel threaded inserts that I'll embed in the cleats and then screw the planks into them. I'm hoping that the cleats will allow water to drain under the planks and the threaded inserts will allow for plank removal for refinishing.

    Denise, I was on the fence about using the tanks for storage and installing larger watertight hatches, but opted for 8" inspection ports because I found I had adequate storage space for a week with 2 people aboard. I spent a great deal of my youth doing ultralight off-road bikepacking trips and my 'kit' is quite austere and feel like traveling in this boat will be quite civilized compared to my bike trips. There is a hatch in the top of one of the seat tanks, but that will be strictly for installation and servicing of the bilge pump and will be screwed down and sealed.




  21. #21
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    Default Re: Attaching planks to seat tanks

    Still a great build! but this boat looks able to handle more then ultra light packing! I loved that about canoe tripping. and having learned to do the minimalist thing when into backpacking It did not take long to get heavy on H2O trips even on the portage we didn't mind the extra weight.

    Carry on!
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  22. #22
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    Default Re: Attaching planks to seat tanks

    Sometimes the first idea is the right one. Looks good to me. Post some photos when it's done.
    - Chris

    Life is short. Go boating now!

  23. #23
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    Default Re: Attaching planks to seat tanks

    So I finally got the job done and I'm pretty happy with the way it turned out. I would have liked having them more easily removable but I hope it will work out ok.





  24. #24
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    Default Re: Attaching planks to seat tanks

    Nice! Looks good to me.
    - Chris

    Life is short. Go boating now!

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