Carvel planking

Discussion in 'Boat Design' started by noahsark, Sep 19, 2011.

  1. noahsark
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    noahsark New Member

    hi apologies if this post sounds a bit stupid but unfortunately we are new to this.the question i have is we are away to start building a 90ft x 19ft house barge in october we have looked at all the alternatives to complete the hull from fibreglass to ply the plans state plywood with a fibreglass skin but we would like to use carvel planking as it looks better in my opinion and hopefully easier to work with the barge is off straight sides and a flat hull the frames are 75mmx150mm spaced four feet apart what my question is if i use carvel planking can i go down a slightly different path and router out 25mm deep x 75mm length on each plank to simply mate together flat(planking is 50mmx300mm and glue inbetween the spaces thanks
     
  2. Tad
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    Tad Boat Designer

    No....

    The framing system is designed to work with the planking as designed, ply and glass....it makes no sense with carvel planking and won't work......and no you cannot glue 50 by 300 mm planks together....

    The structure is a system, planking works with the framing....different planking system means different framing.....you realize that without glass the barge must be hauled frequently for bottom paint?

    Framing on 4' centers sounds bizarre....there must be stringers as well?
     
  3. noahsark
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    noahsark New Member

    Hi tad thanks for your reply

    unfortunately our plans show no stringers on the plans themself or on the material list(this being for the ply on frame construction)would you suggest we add more framing for the original construction and add stringers at foot intervals. the other things that is worrying us is the use of 80x300mm board for the bottom of the hull running all the way along centre interlocking with the framing does this seem adequate? or is this bare minimum also does the actual framing thickness seem ideal thanks
     
  4. Tad
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    Tad Boat Designer

    noah....

    Really hard to comment meaningfully without knowing the whole picture. Usually a lack of framing indicates a very thick skin...like 3 or 4 layers of ply? Are the bottom panels really 4' by 9.5' with nothing breaking them up?

    There is no specific reason for a timber on centerline unless there is an outside keel that the barge is intended to sit on......but this would be unusual....if anything I'd have perhaps four outside runners to sit on if going dry was intended.

    Generally barges are fairly shallow so require significant stiffening inside. Usually this takes the form of bulkheads running in both directions and tying the deck to the hull bottom. The reason for this is without the bulkheads you have a big thin (like a pizza box) floppy box. The box could be stiffer if the sides were higher. Should loading become uneven for some reason (going dry in one corner) there's a possibility the skin will just break open. Bulkheads transfer the loads through the structure.

    If there are no bulkheads what supports these frames?
     
  5. BATAAN
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    BATAAN Senior Member

    Usual frame/plank for 90' barge on west coast US was 8x10 frames on 24" centers, 3" plank, cross plank bottom, much edge-fastening in the side planking, sometimes a caulked edge-fastened ceiling in the sides, 3 longitudinal 6"-8" timber bulkheads heavily edge fastened (3/4" galv about every 18") between bottom and deck plus keelsons about 2' apart.
    I used to caulk the f*****g things and did not enjoy it. Regular expensive haulouts etc.
    Build a steel barge or go with the ply/glass but keep it afloat if possible, they quickly get broken if aground poorly unless they are steel and industrial type.
    Steel is real. Photo of powered 90' salmon packer (buy-boat) that works in Alaska. Steel, nice sheer, heavy rubrails, very very very strong and long lasting if cared for. With proper stray current and zinc management and modern paint, only have to haul about every 7 years instead of every 1-2 like wood barge.
     

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  6. whitepointer23

    whitepointer23 Previous Member

    are you sure you want to build a 90 ft boat , you don't appear to have any knowledge of boat building. who the hell would think carvel was easy. is it a proper plan or a free one off the net.
     
  7. noahsark
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    noahsark New Member

    Hi thanks for the replies firstly to tad
    the original specification was 75x100mm side framing 4ft apart with 75x150 bottom framing with 63x125mm horizontal battons interlocked into each frame one at the top of the framing and the other at the bottom running full length of the hull apart from the framing and the above the only other supports looks like to be the plywood framing which is 2 x 24mm sheets to make the 48mm required thickness and the 80x300mm beam which runs the full length of the keel at the bottom and the 200x100 stern and stem pieces(sorry there are 35x120mm hardwood external rubbers

    whitepointer23

    yes honestly these plans were actually purchased im afraid the reason we went for these ones is because unfortunately we are very much novices and needed something idiot proof to build the reason the carvel framing idea came about is most fishing vessels down here were of the wooden type(to which i thought would be easier and stronger to build)


    after reading all comments everyone seems to state no to carvel planking and stick with the ply on frame and i think i would be foolish to disagree and appreciate all the help offered
     
  8. BATAAN
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    BATAAN Senior Member

    What provisions are made in this complex internal frame to reliably drain bilge water to a sump? This is always a problem with a flat bottom. If still interested in wood barge, find a Thames barge, there are still a few sailed and kept up by amateurs and groups, and thoroughly look it over. You will get a bit of barge school and enjoy yourself a lot. These have double planked sides with no caulking by and large, but appear normal carvel. This adds a lot to the ability to take the ground loaded. If your prospective project was designed by a reputable designer, with a track record of actual things built you can see and check out the problems thereof, follow the plans.
    For the "look" of carvel in the movie boats we worked on, thin wood planks were glued and screwed over a plywood structure built on a steel frame.
    But again, follow your designer's plans and burn up the phone bill calling him with specific questions.
     

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  9. PAR
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    PAR Yacht Designer/Builder

    As novices it would be unwise to re-engineer the structure, for obvious reasons. Your plans could be converted, though you'll likely end up with more work in a carvel build (more frames, stringers, structural floors, etc.) The best advice a novice builder can take is stick to the plans in the structural elements.
     
  10. BATAAN
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    BATAAN Senior Member

    Stick to plans and scantlings, pay close attention to "where the water goes" both below and on deck, and ask questions of your designer to the point of annoying him.
     
  11. boat fan
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    boat fan Senior Member

    Double planked sides....

    Hello Bataan.

    I am interested in knowing about barges built with double planked sides ....

    Are the planks fastened to the frames only , or to the frames ( as well as ) each other ?

    Are scows / barges built in this way cross planked ?
     
  12. BATAAN
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    BATAAN Senior Member

    I went and did some research and learned I was wrong. Thames barges were planked with 3 1/2" oak, single plank, all fore and aft, trunneled, no caulking but hot tar and elk hair between the plank edges. When old, they were often 'doubled' by having a second layer of plank applied, fastened through to the frames, but were not double planked when new. American barges and sailing scows are usually fore and aft side plank and athwartships bottom planking, but not always. They are caulked with cotton, oakum and cement.
     
  13. BATAAN
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    BATAAN Senior Member

    Doubling an old barge was done with 1 1/2" elm, spiked on. Try and find book "Just Off the Swale" by D.L. Sattin, Meresborough Books, 1978. Has wonderful tales of barge building and repair in Conyer UK before ww2. They still used pit saws and he goes into some detail about all the barge building things.
     
  14. MastMonkey
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    MastMonkey Junior Member

    You might be able to learn something from studying some of the SF bay scows or New Zealand scows. There was a lengthy and informative thread on the latter and the maritime museum in San Francisco used to sell study plans of the Alma, a completely restored scow. I can no longer find the link for the plans on the website, but if you called the museum they might still offer them.
     

  15. boat fan
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    boat fan Senior Member


    Yes , I followed that with great interest too....
    I had not heard of the double sided scows before......
     
    Last edited: Sep 26, 2011
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