1980 four winns 160 - transom from outside?

Discussion in 'Fiberglass and Composite Boat Building' started by atengnr, Nov 4, 2019.

  1. atengnr
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    atengnr Junior Member

    Hi all, bought this boat this summer, is in nice cosmetic shape. Used it for the season and finally got around to drilling some holes in transom and found the expected rot, which seems to be central from the drain plug hole, up about 12 inches and out about 6-8 inches either way. Can I replace this transom from the outside? Im not worried about the cosmetics so much, more just producing a functional boat.

    Thanks
     
  2. atengnr
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    atengnr Junior Member

    see pics. That rear splashwell is so large that short of cutting off or removing cap of boat entirely, it seems the an outside approach makes sense (assuming stringers OK).
     

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  3. gonzo
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    gonzo Senior Member

    If you don't care about cosmetics, cutting the aft section of the deck is a much easier job. The outside skin of the transom is structural and will require more expertise, time and money to repair. If the stringers are rotted, which is the most likely scenario, you will have to remove the sole (floor) to repair those too.
     
  4. atengnr
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    atengnr Junior Member

    Thanks ok. Realistically, in the ideal scenario, Id like to get 5 years of service out of this boat. Is it at all possible to scab in a replacement section of transom wood and glass in, leaving the existing wood surrounding it (after giving the wood months to dry with a heater)?
     
  5. Blueknarr
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    Blueknarr Senior Member

    Partial transom replacement is acceptable.

    Repeating

    From the inside is usually easier than from the outside.

    Do you have a router with great deapth control?
     
  6. atengnr
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    atengnr Junior Member

    I dont have a rotor but certainly could get one. Yes i drilled quite a number of holes on the wood more than 12 inches from the drain plug hole is good. How do i best bond the new wood to the old? Epoxy thickened with wood shavings?

    thanks
     
  7. Blueknarr
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    Blueknarr Senior Member

    Do you play well with power tools?

    How I would repair in my shop.

    Working from inside because the inner skin is thinner and less cosmetically critical.

    Set router to a depth which would remove neatly all of the plywood. Keep the shape simple, so that it can easily be matched. I'd rather leave a layer of ply than risk damaging the other skin.

    Remove the last bit of wood and sand smooth.

    Set replacement plywood in thickened epoxy. Temporarily screw from unaffected side.

    Grind bevel to fiberglass skin.

    Replace missing FG with same weave and thickness as original.

    Fair and paint or gelcoat.
     
  8. atengnr
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    atengnr Junior Member

    Ok great. So that epoxy bond is as strong as the wood?

    appreciate the advice. This may allow me to salvage this boat as im not sure that im willing to do extensive repairs on it. Only issue i can think of is whether rot extends up near splashwell which then would make repair more extensive i think.
     
  9. atengnr
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    atengnr Junior Member

    What is best to thicken the epoxy?

    thanks
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    going into extensive repairs on old glass boats, is rarely warranted, unless they are a classic hull that stands out from the crowd. And even then, doubtful. I would be more concerned that any structural failure could cause a safety issue, I would attend to that by ensuring any failure won't cause the boat to sink, by checking ample buoyancy foam is properly installed. But you could say that whether old or new. Unless this is some hard to find super-dooper hull, I would not touch it, unless there are gross and obvious problems, in which case the boat should not be in use.
     
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  11. Blueknarr
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    Blueknarr Senior Member

    The epoxy bond will be as strong as the original FG wood bond. That is as strong as it needs by the original engineering. Most likely a polyester resin was originally used. Epoxy is usually stronger than polyester.

    Cabo-sill or fumed silica is used to thicken resins. Not an exact recipe. Try enough to achieve whipped cream consistency. Too thin and it will run out bottom of repair. Too thick it won't let you push the plywood against the skin. Moma bear just right will squish out the sides when plywood pushed into place.

    Un-cured epoxy cleans up well with cheep household apple cider or white vinegar.

    Measure thickness of original FG skin before adding plywood. Bevel is one inch wide for every 1/8 th inch of thickness. So 1/4 inch = 2/8 = 2 inch wide bevel.
     

  12. atengnr
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    atengnr Junior Member

    Thanks. Ok to use cabosil thickened rpoxy to bond new piece of wood to the existing?
     
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