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Thread: Rudder- Meranti plywood???

  1. #1
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    Default Rudder- Meranti plywood???

    I'm ready to begin the rudder of my Wm Garden Tomcat. The plans simply specify that plywood is to be used. While it's obvious that marine ply should be used, there is no mention of what species. The local lumberyard stocks Meranti- would this be ok to use? Also, should it be wrapped in FG/epoxy? Thanks

  2. #2
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    Default Re: Rudder- Meranti plywood???

    Quote Originally Posted by GregH View Post
    I'm ready to begin the rudder of my Wm Garden Tomcat. The plans simply specify that plywood is to be used. While it's obvious that marine ply should be used, there is no mention of what species. The local lumberyard stocks Meranti- would this be ok to use? Also, should it be wrapped in FG/epoxy? Thanks
    I'm not a fan of plywood for foils. Designers specify them for ease of building, and that's ok - just not ideal. But if you are going with plywood, then, yes, meranti. It's heavier, denser, stronger, and more rot-resistant than the other commonly available marine plywood species: occoume. And yes - I sheathe almost all foils in fiberglass and epoxy, and paint them with a durable 2-part polyurethane (simply brushed, or rolled&tipped).

    The alternative to plywood? Staved construction. Most typical for me is almost all staves of western red cedar (though any decent durable species is fine), with only the more vulnerable leading and trailing edges of something harder/tougher.

    Don't know the shape of your foil, but a compromise might be a plywood blank with those same two leading and trailing staves of solid lumber.
    David G
    Harbor Woodworks
    https://www.facebook.com/HarborWoodworks/

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

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    Default Re: Rudder- Meranti plywood???

    Ok- so I'll go with the Meranti ply - thanks David G. It will be laminated of 3 layers of 3/8" ply (using thickened epoxy) , the face grain of the outside layers oriented horizontally, the inner, vertically. With all that end grain around the edges ( especially after some tapering/rounding) should I seal the edges first with some CPES, or just rely on the unthickened epoxy during the application of the FG cloth?

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    Default Re: Rudder- Meranti plywood???

    Quote Originally Posted by GregH View Post
    Ok- so I'll go with the Meranti ply - thanks David G. It will be laminated of 3 layers of 3/8" ply (using thickened epoxy) , the face grain of the outside layers oriented horizontally, the inner, vertically. With all that end grain around the edges ( especially after some tapering/rounding) should I seal the edges first with some CPES, or just rely on the unthickened epoxy during the application of the FG cloth?
    You trying to start a brawl with that CPES question? <

    Seriously, our approach here is to use neat epoxy, reapplied with still wet, as it soaks in and dry areas appear. Several coats.
    David G
    Harbor Woodworks
    https://www.facebook.com/HarborWoodworks/

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  5. #5
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    Default Re: Rudder- Meranti plywood???

    Got it- thanks once again!!!

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    Default Re: Rudder- Meranti plywood???

    I've made rudders with meranti, epoxy coated, and painted. They've held up well.
    There is no rational, logical, or physical description of how free will could exist. It therefore makes no sense to praise or condemn anyone on the grounds they are a free willed self that made one choice but could have chosen something else. There is no evidence that such a situation is possible in our Universe. Demonstrate otherwise and I will be thrilled.

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    Default Re: Rudder- Meranti plywood???

    People have experimented with and approve of polyester line being epoxied onto the business end of rudders, leaboards, bows, and sterns. Faired out nicely with epoxy. The idea is that it gives you a real tough edge to take the ground. It will also isolate the end of the plywood or laminated wood nicely. I have not tried it yet, but will. I have added 6mm worth of woodfiber thickened epoxy the these edges with a great sucsess, in regards to its abrasion resistance.
    Last edited by Matt young; 07-13-2018 at 04:51 PM.
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    Default Re: Rudder- Meranti plywood???

    Quote Originally Posted by JimD View Post
    I've made rudders with meranti, epoxy coated, and painted. They've held up well.
    They certainly can - if you over-engineer them a bit and/or don't work them too hard or abuse them.
    David G
    Harbor Woodworks
    https://www.facebook.com/HarborWoodworks/

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  9. #9
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    Default Re: Rudder- Meranti plywood???

    As per the plans, my rudder is meranti with a leading edge of thickened epoxy and the whole thing glassed over. I don't worry about it.

  10. #10
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    Default Re: Rudder- Meranti plywood???

    Sounds like I'm on the right path- thanks to all!

  11. #11
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    Default Re: Rudder- Meranti plywood???

    Greg, David's comments ring true and i think you will be amazed with the results

    i was in on a Saturday Night Special build, using meranti plywood, a while back and it called for a wing similar to the picture i found of the Tomcat

    we simply cut a wooden fillet to epoxy in place and it looked clean worked well

    SNS rudder.jpg

    this boat was designed with the Texas 200 in mind and it has held up quite well

    when finishing out the edges of good marine ply simply using epoxy neat as mentioned above will give a nice finish if repeatedly hot coated again as mentioned above

    IMG_1065.jpg

    once you have a good solid/slick base you can finish it as you desire

    you said 3x layers of 3/8"(9mm) fo get the design thickness have you considered using 1/4"(6mm) instead?

    IIRC both 6mm & 9mm in good quality marine ply is 5 ply

    using the 1/4"(6mm) would give you a substantial increase in the number of plies if that mattersą

    GOOD LUCK & HAVE FUN W/ YOUR BUILD

    sw
    "we are the people, our parents warned us about" (jb)

    steve

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