Wooden Ribs and Cemented Bilges

Discussion in 'All Things Boats & Boating' started by Biffyhyndwood, Dec 12, 2010.

  1. Biffyhyndwood
    Joined: Dec 2010
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    Location: Fife Scotland

    Biffyhyndwood New Member

    Hello all,
    I have Slight Predicament, I have a number of broken ribs in my old boat. This isnt a problem however the previous owner has filled the bilge with ferro-cement.
    Now! inorder to attach the ribs to keel i will need to dig it out.
    -How much damage to the keel is this likely to cause?
    -Is there a "best practice" way to remove ferro-cement.
    I might also add that my boat is a 24ft, long-keel, pitch pine on oak, carvel gaff cutter built in 1940. she is out of the water for the season however not under cover.

    Any and all help you can offer would be fantastic.
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    At what point are the ribs broken? You can either sister or scarf them without needing to remove the cement.
     
  3. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Ferro cement or concrete? Ferro indicates steel reinforcement. Concrete can be broken up with a small jack-hammer. Slow and tedious if the bilge is deep.
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Drill holes, then connect the dots with an impact chisel.
     
  5. Biffyhyndwood
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    Biffyhyndwood New Member

    Hi guys, thanks for the speedy replys,
    -The ribs are rotten in places and some have mulitple fractures, sistering just isnt a viable option. Might it be possible to scarf over the top of the cement or will this leave a weak point in the hull wall.
    -I believe its ferro-cement as it has a plastic look and feel. what kind of steel reinforcement could i be looking at? Keel weights for example?
    -Thanks for the tip on breaking up the cement with a drill! great idea.
    cheers
     
  6. gonzo
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    gonzo Senior Member

    I think you need someone to survey the boat. That is the best option, so you can get an informed opinion.
     
  7. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    It's not likely there is any steel in the concrete. The usual course is to just pour it into the frame bays and let it cure.

    You can't scarf over the cement or sister with the condition of the cemented ribs in question. Judging by the condition of them above the cement, you can reasonably assume the same below, which means they need to be replaced.

    The fastest way I've used is a chipping hammer on an air powered impact gun. It's very slow, noisy, dirty work, but if you drill many holes, you can usually remove large chunks after you've compromised the strength of each area. Of course none of this impact hammering does any good to surrounding wooden element fasteners. I usually just make a line of closely spaced holes down the hull centerline, taking care not to bottom through, into wooden stuff. Connect the "dots" and maybe with some persuasion from a heavy hammer and chisel at the bottom of the holes now slot, you can lift out each half from the frame bays. This works about 50% of the time, the rest you divide the pieces in two again with a line of holes, but perpendicular to the first row of holes. Eventually your elbows give out and small hunks of TNT in the holes is starting to look good. Resist this quite natural urge and bang away, you'll get it in time. One tip, lots of little bangs are as good as a few big ones and your elbows will have more durability as a result.
     

  8. Biffyhyndwood
    Joined: Dec 2010
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    Biffyhyndwood New Member

    Thanks for all the help guys. I guess il go get a large hammer! :D
     
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