cracked Cast iron keel on 37' sailboat

Discussion in 'Fiberglass and Composite Boat Building' started by arosental, Jan 20, 2010.

  1. arosental
    Joined: Jan 2010
    Posts: 4
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Sugarland Texas

    arosental New Member

    CI cracked Keel

    we decided based on all the several net discussions to use the cracked keel as a form to dvelop the mold, melt it and repour it into a new CI keel. save about 1.5 $/lb in materials but not telling labor and freight ionvolved. Now Im looking for a repuitable foundry in the Houston area preferably that can do the job. Maybe owned by a sail enthusiast willing to help out some.

    (the attachment button is not working)
     
  2. Sam III
    Joined: Sep 2007
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    Location: League City, TX USA

    Sam III Junior Member

    Not sure but I heard you could just clean out the cracks and re weld it using suitable welding rod.

    That sounds cheaper than a complete re pour.

    Is this an "old wives tale"?

    Sam
     
  3. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    There is a company in Texas that specializes in cast iron welding rods.
     
  4. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    No it is not.
    Cast iron, also the crude gray type can be welded using stainless steel electrodes. I've even repaired an exhaust manifold that way: the repaired spot never cracked again. There are also special electrodes for such a job, but I prefer stainless ones.
     
  5. M-Sasha

    M-Sasha Guest

    You are right CDK,

    but you are wrong also. A keel is much to thick to weld. We have a -weld everything- man here. And he can really weld everything together when ther e is a bit of metal in it (Soviet times are a great teacher) but a keel is too thick.

    arosental do not cast a iron keel again. Make a lead keel. Cast iron is too britle to live long and you have too much rust you can never fight!

    Sasha
     
    1 person likes this.
  6. Petros
    Joined: Oct 2007
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    Location: Arlington, WA-USA

    Petros Senior Member

    The keel is an integral element of the hull, both structurally and hydrodynamically. You should see a good navel architect about designing a new, more modern keel for your hull. It will not be inexpensive, but you could possibly improve the performance.

    You might consider using the old keel as a mold for a new one.

    The only way you can permanently weld cast iron is to heat it up to about 700 deg to get good bond and to limit heat distortion. Not practical with a keel sized object, otherwise it eventually will crack along the weld line again.

    It might be possible to do a bolted plate splice repair, but even fared it would affect performance (not good for racing), and I would consider it temporary at best. Something to use until you can afford a new keel, and I would not push it into rough water.

    Do you know what caused the crack? Resting on the keel it seems should not cause it to crack.

    good luck.
     

  7. arosental
    Joined: Jan 2010
    Posts: 4
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    Location: Sugarland Texas

    arosental New Member

    cracked Keel

    Petros, I believe we corresponded earlier today through the Kyrie Elite yahoo group. For the benefit of futurevisitors to this forum I am pasting a copy of our email.
    "Peter your analysis and evaluation is right on our current thoughts. see below CAPS:

    There is no way an epoxy repair would work [AGREE-NOT CONSIDERED], the metal changes size and
    shape with temp too much compared to epoxy, even if you could get a
    clean bond. Â I do not see how welding it could work, it has to be
    heated to some 700 deg F to limit heat distortion and get a good
    normalized weld [ONLY IN A SHOP BUT DOUBT THAT A 1 FOOT THICK WELD IS POSSIBLE]. Â Not practical on a keel sized object. Â I have seen
    larger cast iron repair welds done sucessfully, not never on anything
    that size. Â There is a shop that specialized in doing cast iron
    welding near me, a very skilled and experienced owner. Â Give me the
    total size of the keel and thickness[APPROX 5' BY 6' WIDE AT THEÂ HULL AND 4' WIDEÂ AT THE BOTTOM. THICKNESS OF THE KEEL IS 1' AT THE BOTTOM AND AM ESTIMATING FROM MEMORY SINCE I HAVENT MEASURED ~6-8 " AT THE HULL]Â and I will drop by and ask him if
    it can be done GREAT. Â It would have to come off the hull [IT'S COMING OFF AND AFTER IT DOES AND WE INSPECT THE CRACK RELATIVE LOCATION AT THE HULL WE WILL CONSIDER THE FOLLOWING ALTERNATIVES].
    SHIP TO FOUNDRY,USE AS A MOLD, RECYCLE THE IRON AND BOLTSÂ AND REPOUR.CI
    REDESIGN IN LEAD AND MAYBE IF MR HOLLAND RETURNS OUR CALLS PUT IN A MODERN KEEL DESIGN ($?)
    HAVE A GENIUS GUTSYÂ NAVAL ARCHITECT DESIGN A FIXÂ BY STRAPPINGÂ -BOLTING AND WELDING THE KEEL TO IT'S ORIGINAL (OR BETTER) RIGIDITYÂ
    I supposed a splice repair can be designed, using bolt on straps. Â It
    would require a stress analyst of the forces on the keel. Â Though it
    will add weight and change the shape of the keel. Â Likely the
    performance will suffer due to the changed shape (more weight can
    often improve performance, as long as the attach point was not
    overloaded),. THANK YOU PETER. LET'S HOPE. IT'S MY PREFERRED OPTION UNLESS I CAN AFFORD A REDESIGNED LEAD KEEL Â

    Just thinking: could a splice repair be designed, and than have cover
    it with a fiberglass faring and design a new, better performing keel
    profile that might perform better and bury the repair? I HOPE!  Possibly, but
    it would be easier I think just to design a new keel ANY NAVAL ARCHITECTS REFERRALS IN CASE HOLLAND DOESNT DELIVER? . the only
    advantage is you might not have to remove the keel from the hull [COST OF NEW KEEL VRS LABOR AT THE SHIPYARD]. Â And there is always a risk of having the splice joints fail.

    No easy way out I am afraid."
     
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