How to protect transom plywood?

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  • amuller


    Replies: 1055
    Topics: 163
    #5482

    This might be a little off-topic, but I’m replacing the plywood on the transom of my little tin boat. Am wondering about the best way to protect it. Soak with resin? Just paint? Linseed oil?


    david-bartlett


    Replies: 1204
    Topics: 97
    #45724

    What I do is first sand it good, then apply a couple coats of epoxy resin, then sand lightly and polyurethane or varnish over the epoxy. Drill all your fastener holes before applying epoxy and varnish.


    mr-asa


    Replies: 794
    Topics: 138
    #45728

    Not sure why you’d apply varnish over epoxy?


    david-bartlett


    Replies: 1204
    Topics: 97
    #45733
    quote Mr. Asa:

    Not sure why you’d apply varnish over epoxy?

    Most epoxy is not UV stable and will break down much faster if unprotected by the varnish.


    mr-asa


    Replies: 794
    Topics: 138
    #45735

    So do you apply a new coat of varnish every year? The UV protection in it breaks down over time and exposure to UV.


    chris-p


    Replies: 2456
    Topics: 153
    #45749

    Good advice from David above. Some guys keep up on their transoms, im a little lazy and let it go for a while!


    sydinnj

    US Member - 2 Years
    Replies: 197
    Topics: 9
    #45753

    If the boat is stored inside it lasts a long time, outside then it needs to be done more often. My Fay Bow outboard from 1931 looks like the day I put it on around 25 years ago. It is stored inside and I used Pettits ultra V Gold. It is a polyurethane. My Hacker Craft which spends much more time in the sun lasted 13 years before I redid the finish.


    george-emmanuel

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 498
    Topics: 36
    #45757

    My 2 cents: When installing any wood in a boat use a marine grade. There are all types of "marine" plywood. Marine fir is probably the most common but it isn’t what it used to be! So I treat all plywood with Smith’s Clear Penetrating Epoxy nicknamed CPES. It soaks into the wood deep. Thoroughly saturate the outside edges of the plywood, let it cure and then use your finish. I prefer Sapele but at about $100/sheet it scares people.

    If you encapsulate your transom you are asking for trouble. Water can enter from the slightest crack/hole and can’t get out. At that point rot begins and goes wild. My personal preference is to treat with CPES then varnish. I don’t use polyurethanes when cosmetic appearance is important because they are more difficult to deal with later on.


    wiscoboater


    Replies: 739
    Topics: 126
    #45763

    Most of the CPES available can be cut 50% with Acetone to thin it to a water like state. Using that as your first coat, followed by an uncut second coat will dramatically increase the level of penetration into the wood. Doing it in that way will outlive us all. See a demonstration of this method at the Jamestown distributors web site. They sell top of the line boat restoration supplies.


    amuller


    Replies: 1055
    Topics: 163
    #45764

    Thanks for all the input. Lots of opinions on this, and no perfect answers. I favor penetrating materials over an impermeable surface coating, because the barrier will likely be imperfect and saturation will result. There is not a huge amount at stake with the plywood pads on a tin boat, but an encapsulated plywood transom on a chopper-gun fiberglass hull is a whole different story…..

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