Laminate 1" x 3" stringers?

Discussion in 'Boat Design' started by abosely, Aug 2, 2016.

  1. abosely
    Joined: Mar 2015
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    abosely Senior Member

    Can 1" x 3" stringers for a Wharram be laminated from two pieces to obtain the 1" thickness needed?

    The stringers are 1" x 3" but getting actual 1" thick finished stock here is a lot more difficult and expensive. But I can get rough sawn 1" stock that will plane down to 3/4" stock for good price.

    So wondered if it would be possible to either laminate 3/4" with 1/4" material or plane the 1" rough sawn stock less than 3/4" to have the two layers of the laminate closer to equal thickness?

    Or is this just not a good idea?

    Cheers, Allen
     
  2. rasorinc
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    rasorinc Senior Member

    Laminating lumber into 2 pieces using EPOXY as the adhesive is usually
    stronger than a solid piece. However I do not what lumber species your using. Do not use Balsa........................make sure you ruff up the 2 bonding sides so the epoxy can get a good bite. Do not over clamp.
     
  3. abosely
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    abosely Senior Member

    Probably be Douglas-fir or Eucalyptus deglupta. Basically a wood comparable to Doug fir strength wise.
    And yes it would be System Three SilverTip GelMagic epoxy, completely encapsulated with System Three epoxy.

    Cheers, Allen

    .
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I'd recommend you saw the stock thinner, so you can use 3 laminations, instead of two. We call this a balanced laminate and you can use the off cuts for other laminates. If you need 1x3 actual size, saw some stock to 3/8" thick, 3" tall. If using a small table saw, you'll have to flip each board, but this is a common tactic, assuming the saw is square. There's some waste, but less than planing it down to size from 3/4" stock. I'd also recommend one of the discount epoxies, instead of West System or System Three products. These work fine, but you pay well over $100 a gallon, while the discount epoxies (RAKA, Bateau.com, epoxyproducts.com, etc.) are at least half as much with the same physical properties.
     
  5. abosely
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    abosely Senior Member

    I was hoping you would chime in. Actually using 3/8" thick laminations opens up some options in how the lumber is cut for grain orientation and shape of lumber being used.

    I guess an advantage of laminating the stringers is I can stagger the scarf joints in the three laminations to make the needed lengths instead of a scarf joint in the 1" thick stringer.

    Is it an issue if the three pieces of the lamination are somewhat short as in 3' to 8' or so.
    As in using some shorter pieces sometimes when cutting out knots. I would use as long of pieces as possible, but if I can rip lumber that has some knots and work around them that would be a benefit. Not something I would want to do with solid 1" thick stringers of course.

    I'll check out the other epoxies. thx.

    Cheers, Allen
     
  6. PAR
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    PAR Yacht Designer/Builder

    Nope shorter pieces are fine, regardless of the length of the piece. You have to work with what you've got. If the piece is highly loaded, make a 12:1 scarf, otherwise an 8:1 will do fine and if lightly loaded 6:1 can do. If there were more laminations in this stringer, you could just butt joint the laminations.
     
  7. tane
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    tane Junior Member

    as far as I remember my wharram-build (70ies...)jim's "1 x 3" always meant "rough & planed 20 x 70mm; seem to recall my tangaroa-stringers were "1 x 3"
    laminating would entail lots of work & glue...(but of course laminated "on the bulkheads" would mean a stronger construction as they'd be laminated with curvature...
    (surprised that these days wharrams still get built even though lots of better designs, just as easy to build are around...)
    stringers out of 3' pieces??? matchwood!
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    A 1x3 is dimensional lumber, if an odd size. It's finished dimension would be 3/4" x 2 1/2" or 2 5/8". I agree in as much there are a lot of designs available offering a lot more than these dated ones, but who's to say what someone else likes. Laminates, even with short pieces, are quite valid and testing has shown this repeatedly.
     
  9. abosely
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    abosely Senior Member

    Lol Yes they are a bit dated and old fashioned. But for me that's a good thing. :)

    I have the Narai Mk 4 plans and was going to build it, but a health issue changed my direction somewhat. Want something smaller now.
    It will be a coastal/inter-island cruiser now. Not a voyaging, long term stay aboard. The temperature is nice year round here so want a covered deck. More of a rugged expedition/camping type boat.

    Still deciding between Tanenui and Tangaroa Mk 4.
    I 'talked' with Hanneke about a stretching the Tanenui by adding 36" (28' LOA to 31' LOA in center of hulls and raising the deck 8" and cabin tops a few inches. It wouldn't give standing head room, but would would go from 54" to 65" or so and widen over all beam accordingly also. At least would be able to stand up a little bent over to change clothes. She said this wouldn't be a problem.

    If I go with the Tangaroa Mk 4, would stretch hulls 30" in center with beam widened from 19' to 21' or 22'. Stretching the hulls 30" gives some usable room in cabin. Hanneke said she thought this would be a good modification and recommended it.

    The nice thing about the Tangaroa is that it will have 6'-3" headroom.

    Cheers, Allen
     

  10. tane
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    tane Junior Member

    OMG, a Tangaroa! we had a mk1, the mk4 is a definite improvement but still...(don't get me wrong, 7years rtw was "the" adventure of a lifetime...but for the same building-effort we could have done A LOT (& I mean L O T!!!) better (yes, lotsandlotsandlots!!!)
    if you're changing things around: make the companionways facing AFT!!!
     
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