Spline/Batten material & how to splice?

Discussion in 'Boat Design' started by abosely, Sep 11, 2015.

  1. abosely
    Joined: Mar 2015
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    Location: Big Island Hawaii

    abosely Senior Member

    What would be a good material or wood to make a spline/batten that can be spliced in one or two places and how do I splice it so it will make/maintain a fair curve?

    Would like to have it about 20' long and will only be used once to loft the keel and top line of bulkheads full size for Wharram Narai.

    Would MDF ripped to size and spliced work or should it be made from solid wood? If wood, what is a clear species that would work well and be available from a box store?

    Would a 12 to 1 scarf joint maintain a even fair line?

    Cheers, Allen
     
  2. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    12 to 1 should be good, don't go lower.
    Solid wood, vertical grained if you can get it. Not MDF.
    Make your splice in over sized wood, then rip it to size cutting evenly off all sides until you get what you want.
    My guess is you would want something 1" square, finished size.

    Personally I would use something stiff, not cedar.
    The biggest thing is to choose lumber which is absolutely as straight as you can find before you splice with no larger knots.
    Use a piece of angle iron to align the boards straight before you glue the scarf.
    Make sure you use some packing tape on the surfaces of the angle iron to keep the splice from sticking (actually I use aluminum cause I have it - check to see that it is straight also - about 6' would be best). Clamp in the middle of the splice, at the end of the splice, and at the end of the angle. Be sure to clamp in both directions to get the spline as straight as possible.
    Use epoxy for the splice.

    On the other hand, you could buy a 20' length of aluminum square tube, checking to see that it is straight. More money but easier to be sure of. Protect it to be sure it does not bend in handling.

    I never got to the Big Island. Does this qualify me for a ride on your Narai when its finished? :D:D:D

    I hope this is a start of a How to build it blog. Have fun.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Straight grained Douglas fir or any other good straight grained species will do, even cedar, though the lighter softwoods tend to be too flexible. 12:1 is standard and easy enough to do on the table saw. The dimensions should be scaled to the most severe bend. 1" square is fine for many things, but if the curves are "quick", 3/4" may be better. If you cut the batten 3/4"x 1", you'll get a more flexible battens on the 3/4" side. while still have a fairly stiff one on the 1" side. You do need to be aware of this, as one curve struck on the 1" side will be different then the 3/4" side. I dislike aluminum tubing, as it takes a "set" if bent very far, which can screw with other curves later on.
     
  4. abosely
    Joined: Mar 2015
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    abosely Senior Member

    I checked and can get a clear Douglas-Fir 2x4x16'. I'll get one and rip a few battens 1"x1" & 1"x3/4" 16' long. I checked plans and that will span 4 stations without needing spliced.

    I'm guessing that it is better not to have a splice if possible for getting smooth curve? The curve is about 1" per foot.

    Or if making a 12 to 1 scarf and then ripping to size isn't an issue, I can use a 12' and be plenty long.

    Yes upchurchmr, I'll be posting about the build and the lofting of the keel & bulkheads. I want to check the fairing midship as I'm stretching it 2', don't think it will really change much, but Hanneke suggested checking the fairing just to be sure, 2' more on 40'6" probably won't change it much.
    After I get going and actually have something to post, I'll start a build thread. It's going to be a pretty slow build at first.

    Maybe I'll post the design/styling details. She's going to be as traditional styled as possible. Late 1800s - early 1900s looking. Well other than being a Cat. Things like no winches, Schooner, wood deadeyes, sheave blocks, all rope rigging, no SS, some bronze, lots of wood, some bright work etc.. Will be looking for ideas & suggestions on styling & such.

    Thinking about making a simple blog to have a place to put more detailed pics if anyone would like to see more construction details. But it will be a build blog, not about me and how my day is going type. Lol

    And sure, when she's finished anyone is welcome to come over and we'll go for a sail!

    Cheers, Allen
     
  5. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    See if clear vertical grain Douglas Fir flooring is available. If so you can rip strips from it.
     
  6. Earl Boebert
    Joined: Dec 2005
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    Earl Boebert Senior Member

    Aircraft Spruce and Supply sells 1x1 inch aircraft grade spruce capstrip in lengths up to 12 ft for $4.00 a foot.

    Cheers,

    Earl
     
  7. LP
    Joined: Jul 2005
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    LP Flying Boatman

    :eek:

    I little bit of time invested at the local big box store will net you usable material at a fraction of the cost. It's one of those things you do when you have a little time on your hands. Think of it as going on a treasure hunt. Sort through the big'uns as they will have clear runs in them more often that the smaller stock. They have to come from bigger trees. I have some nice 16'ers cut from a 2X10. The same boards may have been used to make sheer clamps on my current build.
     
  8. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    Extruded fibreglass pultrusions are pretty good. Think extra long constant section sail battens, but much stiffer constant sections are available. They tend to take a set less than aluminium but must be stored as straight as possible.
     
  9. buzzlymutt
    Joined: Jul 2008
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    Location: auckland.new zealand

    buzzlymutt Junior Member

    Or just use your stringers as battens! Pick out a good one,or assemble a good one out of what you have already.
     
  10. abosely
    Joined: Mar 2015
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    abosely Senior Member

    I would but haven't cut the stringers yet. I'm cutting Eucalyptus deglupta trees & milling the dimensioned lumber.

    Cheers, Allen
     
  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Making battens is a ritual and prerequisite for boat builders. Most have several of various dimensions and lengths, including a favorite, which might seem odd, until you've used them a lot. Some seem to bend "sweeter" than others of the same dimensions, so you tend to use it more often. Make you batten at least 10%, preferably 20% longer than the curve you're drawing. This will prevent the ends of the curve from flattening out in use. In other words, if you're drawing a 10' long curve, setup to draw 12' and draw this curve as if the lines extended the full 12', insuring the ends of the batten are supported. If you don't you'll have flat spots at the ends.
     
  12. Jammer Six

    Jammer Six Previous Member

    I use clear pine.
     
  13. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    A call to a sail maker may find pulled GRP battens in any length.

    It should be 1 1/2 inches wide and will curve fair.

    Recycle it in your sail.
     
  14. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Most of the sail makers I know cut their battens from manufactured GRP sheet stock. It's available in 4'x8' sheets, but most don't buy this length, just the typical widths they usually cut of the thickness they need. An 1/8" 4'x8' sheet is about $150 bucks.
     

  15. LP
    Joined: Jul 2005
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    LP Flying Boatman

    I quick shot of what can be found at the Depot. I picked this board up on one of my "treasure hunting" missions. 16' of 2x10 or 2x12. It's been laid up in my shop for over a year. Yesterday it was cut to make longitudinal components for my current build, though it could have just as easily been used to make battens.
     

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