Distorted deck plating

Discussion in 'Metal Boat Building' started by spaceboy, Aug 28, 2018.

  1. spaceboy
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    spaceboy Junior Member

    Hi all,
    I have enclosed some pic's of the deck of a steel ketch, as you can see the plating is not great to say the least. the hull was built in a professional yard, but the deck was fitted elsewhere.

    P1012957.JPG P1012956.JPG P1012970.JPG P1012961.JPG

    Any pointers as to the correct/best way to rectify would be appreciated.

    I don't want to remove it, I was thinking of cutting along the butt welds then pushing the plates up and re-welding. I would probably need to remove the deck beam welds also.
    Some of the beams are not level either, and one is twisted.

    The boat was intended to have a teak deck laid on top, so perhaps the intention was to hide the bodge up. Although how would one lay a fair deck on that. I'm having painted decks so as it stands it would be an eyesore.
     
  2. JamesG123
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    JamesG123 Senior Member

    That does look pretty bad. Almost like it was intentional. I wonder if it was welded up when it was really really cold and thermal expansion has caused the plates to buckle like that... It will take a complete rework though. those plates will never lay flat again.
     
  3. spaceboy
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    spaceboy Junior Member

    I'm hoping to at be able to remove most of the warp by releasing the welds, cutting the butt welds and clamping it all fair before tacking up. I guess it must have been welded up by a dressmaker.
     
  4. TANSL
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    TANSL Senior Member

    It is possible that the deck, which is very far from the neutral axis of the main transversal section, has buckling problems due to the lack of longitudinal reinforcing elements.
     
  5. JamesG123
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    JamesG123 Senior Member

    By the windows it appears to be a cabin roof, which would take it out of most of the hull twisting forces.
     
  6. SamSam
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    SamSam Senior Member

  7. Ad Hoc
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    Ad Hoc Naval Architect

    Wow, some serious distortion.
    Without seeing the whole deck, and values and location of, and associated adjacent stiffness etc but...it is possible, but it wont be pretty nor easy.
    It really needs a proper onsite survey to give sensible advice as to the extent and remedies required.
     
  8. M&M Ovenden
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    M&M Ovenden Senior Member

    Agree, some more pictures would be needed to give good advice. Do you know the history ? Was the deck like that from day one ? If the boat is all opened up for refit I wouldn't hesitate cutting the whole lot out and starting new.
    Cheers,
    Mark
     
  9. spaceboy
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    spaceboy Junior Member

    Thanks for the replies gents, it must have been fitted like that M&M, she was never completed. She was moved after the hull was completed to have the deck done before she was blasted. I don't know how it got past the owner because he was very particular by all accounts. It's a 57ft Alan Buchanan Ketch, the frame spacing is 18 inches, the level in the photo's is 6ft. some more pics of deck here. Can take more pics if anything particular needed.
    Thanks again guys.
     

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  10. JamesG123
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    JamesG123 Senior Member

    If she was never completed perhaps the particular owner refused to accept it and the builder decided it wasn't economical to rework it and so wrote her off?

    Despite being ugly, the decks are probably structurally sound. Many large thin wall steel structures wind up looking like that over time. You can think of it as "pre-stressed". LOL. If you are willing to do the tedious job of accounting for the lumpy deck, it could be planked over and it would be outofsightoutofmind. Wood decks hide a lot of sins on boats of all kinds.
     
  11. spaceboy
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    spaceboy Junior Member

    As far as I can make out from the correspondence between ship yard and owner, the hull was delivered complete, ready for fit out.There was some remedial work needed but can't find any mention of decks yet. Soon after, the yard went into receivership, and there were contractual difficulties throughout the build, so maybe the correct deck weld up sequence was not followed and left to be snagged at a later date. It's definitely sound, built like a brick s*!"thouse. But I couldn't live with decks like that so I will have a go at it.
     
  12. M&M Ovenden
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    M&M Ovenden Senior Member

    It's unclear to me if it's the whole deck or just one section. If it was just the few plates like in the first photos I'd just cut it and start again (assuming empty hull)
    Mark
     
  13. MikeJohns
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    MikeJohns Senior Member

    On smaller vessels inboard of a two foot margin "deck shelf" you can get away with all sorts of dodgy fabrication practices with steel. A lot can be done with cutting and re-welding to straighten both frames and plating. The plating is slit with a decent gap dogged, and re welded, weld shrinkage is used to advantage, heavy hammers and line heating have their place too.
    Frames are slit normal to the frame with a 9" cutting disk right down through the plating and the frame web sometimes in several places. Then the frame is jacked or pulled to shape and re-welded. I've seen some very distorted decks straightened to an acceptable standard in just a few hours. But you want to involve an older "boilermaker" or Dutch commercial steel boatbuilder if you can find one.

    If doing it yourself it might be easier to cut out the worst and re-build it anew. The decks might be a bit light if they were meant to have wood over. Usually the teak is counted.

    Any idea who designed it and what rule it was designed to ? Did you get any access to a weight study and stability info ?
     
    Last edited: Sep 3, 2018
  14. SamSam
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    SamSam Senior Member

    Is it a small area or is the whole deck like that?
    As far as the "flame straightening" has anyone ever tried it or does it work? If nobody knows I would sure try it as you really have nothing to lose and it seems the least invasive type of fix. Try one of the panels and see what happens.
    In shipyards, do they have an equivalent product to "floor leveler" like you use in a house to level up typically lumpy subfloors before the finished floor? In a big, heavy steel boat like that the weight of a couple hundred pounds of leveler wouldn't make much difference.
    I don't understand what this means...?
     

  15. TANSL
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    TANSL Senior Member

    It is a method widely used in shipyards for many years. It is very effective but must be applied by expert staff, with adequate blowtorches, so as not to burn the material that would become brittle.
     
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