Rust removal

Discussion in 'Metal Boat Building' started by aspirin, Sep 24, 2010.

  1. aspirin
    Joined: Sep 2010
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    Location: Finland

    aspirin Junior Member

    I'm considering about buying a unfinished 60' steel vessel that has been docked for over 20 years. The vessel has been owned by a shipyard after the original client went bankrupt.

    The outside of the hull has been painted with primer and is in good condition. The inside of the plates have rusted from moisture in the air.

    What good methods are there for removal of the rust? Is sandblasting the best option? What about rust converting primer?

    I have attached a picture of the condition of the interior.

    Thanks for your advice!
     

    Attached Files:

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  2. hoytedow
    Joined: Sep 2009
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    hoytedow Fly on the Wall - Miss ddt yet?

  3. apex1

    apex1 Guest

    Before you invest in anything, get a sound measuring of the plate thickness. Measure (or let it do) at the areas looking worst. When there is no massive loss of thickness, you may go ahead with blasting and painting.
    Rust converting primer exists only in TV spots.

    Regards
    Richard
     
  4. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    The only chemical way to remove rust is the use of phosphoric acid. It is a slow process, especially at low temperatures, and because it is a liquid, walls need to be brushed repeatedly until all rust has disappeared.
    When all rust is converted into black iron phosphate, the excess acid must be washed away before a primer is applied. That is why rust converting primer is a fairytale.

    This is only done if the rust is superficial and sandblasting is problematic, both that and chemical removal is a messy job.
     
  5. dskira

    dskira Previous Member

    You will need a lot of......aspirin.:D
    Sorry about the bad joke, but you inspired me. :)

    Seriusly, 60' of what you shows us, will make anyone running.
    But yes measure the thickness, and then decide. But in any circumstance it will be a very long and unpleasant job.
    But if the yard gave it to you, and the plate are not gone, just remember the hull is a fraction of your future expenses.
    Check the papers if the boat doesn't have a lean on due to the bankruptcy of the owner.
    These situations are always in the grey area waiting for the sucker to come.
    I wish you luck
    Daniel
     
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  6. alidesigner
    Joined: Nov 2006
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    alidesigner Senior Member

    All primers are porous execpt epoxy eurethane primers, so you should check what primer is on it. There might be rust under it.

    Also check out the Por 15 range of products.
     
  7. aspirin
    Joined: Sep 2010
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    Location: Finland

    aspirin Junior Member

    I'm going to get the vessel surveyed if the repair offer of the shipyard is acceptable. The shipyard is in Estonia so I'm hoping to get a good price on the repair work. The price of labour is wery low there compared to Finland where I live.

    I'm aware that the hull is only a small price of the finished vessel. I've heard a rule of thumb that 1/3 is the hull, 1/3 is technical systems and 1/3 interior. Do you think this is about right?

    Really? I have user a rust converter on rusted parts on my motorcycle and it has worked great. The rust is converted into a black stable surface that won't rust any further. Maybe it's different on the scale of a boat.
     
  8. apex1

    apex1 Guest

    Yeah, really! But you are right here, on your bike it may work, on a boat it does not. And the rust is not "converted" into a load bearing material, it just stopped to oxidate further.

    Regards
    Richard
     
  9. jimbo2010
    Joined: Sep 2010
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    jimbo2010 Junior Member

    Por 15, buy and apply 1 quart I think you can go sailing very quickly.

    No sanding no sandblasting.

    POR is paint over rust and it really works
     
  10. wardd
    Joined: Apr 2009
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    wardd Senior Member


    I like it
     
  11. apex1

    apex1 Guest

    Please,

    donĀ“t talk the people in such nonsense!

    Of course it does NOT work.

    Do you really believe that the entire shipbuilding industry is sleeping?
     
  12. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Sure it works.... as long as paint doesn't fall your happy thinking rust is gone.
    Out of sight - out of mind.
     
  13. wardd
    Joined: Apr 2009
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    wardd Senior Member

    you could sand the rust off a quarter sized area every foot or so and the paint will have somewhere to stick
     
  14. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    air operated needle scaler...if the metals thin you will find out not as messy as sand blasting or chemicals
     

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  15. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    Nice tool Pistnbroke, but don't you think it is a bit small?
    Aspirin's hull is 60 feet, not 60 inches...
     
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