Plywood Tornado US21 Hull Repair

Discussion in 'Multihulls' started by Burnside Style, May 1, 2022.

  1. Burnside Style
    Joined: Apr 2019
    Posts: 14
    Likes: 1, Points: 3
    Location: Ocean Spring, MS USA

    Burnside Style Junior Member

    Last weekend I picked up an old tornado - was out looking over a prindle 19mx with a friend and saw the tornado in the back corner of the yard we were in.
    Long story short, it seems to be a very early plywood build. The sail number is US21 and both the main and one of the jibs have a stamp from Cork week in 1971.


    Also, here is a link to a google drive photos with photos.


    I know that I am missing several things:
    • Gooseneck
    • Port side trampoline track (small bolt rope track?)
    • Stbd side centerboard pivots (the stainless plate with a pin that is mortised into the side of the centerboard case)


    So far I have:
    • Removed all four beam troughs and made new parts to replace them (there was rot on the rear two beam troughs, so I figured I should replace all four.
    • Removed and labeled all deck hardware.
    • Sanded port deck nearly all of the way back to plywood


    The plan is to:
    • Remove paint, and cover hulls and decks with fibreglass
    • Over-drill, epoxy fill, and redrill for hardware throughout the hulls
    • Scarf in patch on small hole (on hull side/btm) behind port side centerboard slot
    • Make new beam straps from stainless ( I am missing 6)

    My question for this forum is about the repair of the tortured plywood hull. What is the best way to go about fixing this?

    IMG_0780.JPG IMG_0796.JPG
     
  2. redreuben
    Joined: Jan 2009
    Posts: 1,999
    Likes: 223, Points: 63, Legacy Rep: 349
    Location: South Lake Western Australia

    redreuben redreuben

    Cover some bendy ply in packaging tape
    Screw onto hull to level the splits.
    Glass from inside
    Remove ply fill gaps and holes and glass over outside.
     
    BlueBell and oldmulti like this.
  3. Burnside Style
    Joined: Apr 2019
    Posts: 14
    Likes: 1, Points: 3
    Location: Ocean Spring, MS USA

    Burnside Style Junior Member

    Got it, thank you.
    Last night, while removing layers of old paint, I found a similar repair that had been done on the rear stbd hull deck.
     
  4. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    Yeah that's the fun part. You have to cut another hole in the deck to do that - which then has to be fixed. Maybe a round threaded deck plate can be used as the deck patch - if you can find a flat enough part of the deck to make it work.

    Alternatively, for tortured ply and hot molded hulls such as the old Luders boats that were built in old WWII wooden airplane wing kilns, you can fit small ribs inside the hole filling most of the hole. These are strips about 3/4 by 1/4 inch that are spung and glued into place with a screw through a bridge piece. Then you can work a patch over the ribs. High density 1/8 pvc foam works well (like divinycell H250). This can be sanded fair to the hull because it is softer than the hull. Build up with a good primer, fair again. Then a primer sealer and glass veil if you are so inclined.
     
    Last edited: May 3, 2022
  5. redreuben
    Joined: Jan 2009
    Posts: 1,999
    Likes: 223, Points: 63, Legacy Rep: 349
    Location: South Lake Western Australia

    redreuben redreuben


  6. Burnside Style
    Joined: Apr 2019
    Posts: 14
    Likes: 1, Points: 3
    Location: Ocean Spring, MS USA

    Burnside Style Junior Member

    That was my plan - people seem to put them in behind the centerboard case. I can get to the inside where the repair needs to be made as well as, forward to the chain plates from there.
     
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