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Thread: Transom material for a small dinghy

  1. #1
    Join Date
    Dec 2008
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    Default Transom material for a small dinghy

    Folks,

    I'm building a Redshank (7.5') lapstrake dinghy using Western Red Cedar. The plan calls for 1/2" ply for the transom, but I'd like to use something like mahogany to look pretty varnished. Though the transom is only 14" high, I'm worried about wood movement once the boat is complete. Is it a bad idea to use real wood rather than ply?

    Thanks in advance.

  2. #2
    Join Date
    Oct 2013
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    Default Re: Transom material for a small dinghy

    miranti or okoume marine plywood

    good marine plywood will have more layers than the cheaper stuff

    good 1/4" is typically 5-ply

    laminate from several layers of thinner material(1/4"x3=3/4" or 6 layers =1.5")

    can be finished bright quite nicely

    1st coat of bluue.jpg

    and the resulting multi ply edge grain is beautiful... at least to me ;-)

    IMG_1065.jpg

    epoxied w/ 2-3 coats then finished w/ 3 coats of high gloss UV protecting varnish makes for a conversation piece that is quite sound

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

    steve

  3. #3
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    Default Re: Transom material for a small dinghy

    I'm assuming you're doing traditional construction since you mention WRC. If so, you'll be fine. Much larger transoms are made with real wood all the time. Use good quartersawn stock to minimize movement and, moreso, warping.

  4. #4
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    Default Re: Transom material for a small dinghy

    Keep it light would be my vote.

  5. #5
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    Default

    Real wood will be fine. Particularly if you poxy it before you varnish it.

    Sent from my CPH1851 using Tapatalk

  6. #6
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    Default Re: Transom material for a small dinghy

    While I appreciate the extra effort with the varnish on the forward transom in photo#1 of the blue pram. It seems a bit abrupt to my eye. I think the boat would be better without that varnish and I normally like varnish! No offense intended Swoody!
    Jay

  7. #7
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    Default Re: Transom material for a small dinghy

    If using real wood, which I agree is much nicer, consider using two boards with a splined joint.
    IMAGINES VEL NON FUERINT

  8. #8
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    Default Re: Transom material for a small dinghy

    I also like transoms made of solid wood as they are much easier to fasten to and much stronger in the offing when made of the right stock. Honduras is nice!
    Jay

  9. #9
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    Default Re: Transom material for a small dinghy

    Quote Originally Posted by Jay Greer View Post
    I also like transoms made of solid wood as they are much easier to fasten to and much stronger in the offing when made of the right stock. Honduras is nice!
    Jay
    This is one of those rare occasions when I am at odds with Jay.For a dinghy,i am more than happy to use a ply transom with fashion pieces to fasten to.You only need to add the thickness around the edges and the thickness can be useful when trying to screw a plank in place without starting a split in the plank end.You also have the chance to avoid fixing into end grain as you progress up the topsides.

  10. #10
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    Default Re: Transom material for a small dinghy

    Many boats are built the other way around, with ply hull and solid wood transom, due to the fact that edge-fastening into plywood is not a good thing. Go with any solid wood that strikes your fancy, but quartersawn and a species with minimal movement is better.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  11. #11
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    London, Ontario Canada
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    Default Re: Transom material for a small dinghy

    My cedar strip has a mahogany transom and so did 2 of my inflatables
    3 other inflatables have plywood (Marine)
    so it’s 50/50. Both work quite well
    but I agree with Thorne for the edge fastening and with you & Jay - The mahogany are much prettier than plywood when they are finished/varnished IMHO
    Last edited by Pond Hopper; 06-09-2020 at 08:46 PM.

  12. #12
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    Default Re: Transom material for a small dinghy

    Bella (my 17' glued clinker diesel powered day launch) has a ply transom which I laminated with black wattle (an Australian native) - the wattle comes up with a lovely finish, it it did cup after about 6 months which I resolved by some judicious drilling glueing and plugging. My recent build has a solid cedar transom. Both boats are glued clinker plywood hulls. I glue an extra line of timber around the inside edge of the transom which I use as a base to pull in the planks at the stern - so I avoid putting screws into end grain.

  13. #13
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    Default

    These 3 are all solid wood transoms. The bottom one is about 30 years old, the middle one 10 and the top one 3. Just a few planks, edge glued with epoxy. Hulls are ply.

    Sent from my CPH1851 using Tapatalk

  14. #14
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    Default Re: Transom material for a small dinghy

    When you are edge gluing with epoxy, would using biscuits be a good idea. I realize you don't want o squeeze out all the epoxy from the joint, jut how tight do you make it? Is there a rule of thumb?

  15. #15
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    I think if you trust epoxy you don't need biscuits. If the epoxy lets go the biscuits aren't going to save it. I made the edges pretty rough, then clamped them reasonably tight.

    Sent from my CPH1851 using Tapatalk

  16. #16
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    Boise, ID, USA
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    Default Re: Transom material for a small dinghy

    Biscuits don't had much in the way of strength to a joint. I do use biscuits when edge gluing but only to help keep the two pieces in alignment.

  17. #17
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    Default Re: Transom material for a small dinghy

    What about epoxying some 1/8" verneers of mahogany or other to the ply...that's what I've been contemplating on my dinghy restoration....?

  18. #18
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    Default Re: Transom material for a small dinghy

    The transom on my new wooden Lightning is WR Cedar . . . same as my 1956 Lightning, which is still solid. I used dowels to help line things up for the epoxy glue job. I also mounted cheek frames inside the transom to increase the glue and screw area, but that may be overkill for your project . . . I painted rather than varnished the transom just because one of the 3 WR Cedar boards turned out to be a lot darker than the other two.

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