Barnacles on Copper?

Discussion in 'Materials' started by Jacques B., Mar 16, 2014.

  1. Jacques B.
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    Jacques B. Junior Member

    When the Neeltje left Fort Lauderdale last April, she did so with a fresh antifouling on her steel hull, and a new copper-cladding on her barn door rudder.

    When I had her hauled out the following July, her steel hull was almost totally barnacle free, but the copper cladding on the rudder looked like an oyster farm.

    Since I'd always thought copper was the main active ingredient in antifouling paints, I'd left the cladding bare thinking that no barnacle would come near it.

    I've scraped all of the residual barnacles off at this point, but I'd like to know if anybody has a suggestion as to how I should treat (paint) said copper cladding before I splash her again.

    Thank you, as always, for your undying support!

    Jacques
     
  2. michael pierzga
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    michael pierzga Senior Member

    Yah..barnacles will grow on dirty copper. When you sit in port copper gets fouled. Best to paint it...primer, then antifoul if the boat will sit still.

    If painting is not practical perhaps just clean it up then coat it will lanolin. Even a lanolin coated surface will foul over stationary periods.
     
  3. rwatson
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    rwatson Senior Member

    Wow - I too was under the impression that copper was a good anti-fouling, so I did some research out of curiosity. It seems the fault is a layer of marine bacteria.

    "“If you clean a ship or put a new ship to sea, it’s coated with microbes within a day,” said Van Mooy. “Not enough to see, but the first microbes are starting to lie down. And then the slime begins to grow over the course of weeks. That is essentially a gateway community to the barnacles and other things.”

    “The slime” is a biofilm, a thin sheet of bacteria that stick to each other and to a matrix of molecules they exude to communicate with each other and to provide a hospitable environment for themselves. Once the slime forms, the rush is on, as algae and the larvae of creatures such as barnacles attach and begin to grow."


    Fascinating stuff.

    http://www.whoi.edu/oceanus/feature/barnacles-and-biofilms


    Heres another interesting factoid I liked

    "A 2011 study estimated that biofouling increases the frictional drag on ships so much that it costs the U.S. Navy between $180 and $260 million per year in added fuel use."
     
  4. CDK
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    CDK retired engineer

    Contrary to widespread belief, pure metals are not poisonous, with the exception of radioactive ones like polonium. Several years ago terrorists injected oranges with mercury; nobody was harmed.
    Copper as a compound like -oxide or -sulphate are poisonous for marine life, even more poisonous are organic compounds like -citrate or -tartrate.
     
  5. michael pierzga
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    michael pierzga Senior Member

    Yup. Antifoul leeches , erodes and prevents this film from building up.

    The epoxy copper paint.. coppercoat.. Works very well. When stationary it fouls. After a wash off the surface becomes active again and off you go.

    If you are painting a small new build Id give it a try. i see some small craft in the harbour that have copper coat bottoms that are five or more years old. They get hauled in spring , power washed then put back in...no painting.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Wasn't copper sheathing originally to keep out the Teredo ?
     
  7. michael pierzga
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    michael pierzga Senior Member

    Yah...copper protects the wood but it also has antifoul properties
     
  8. rwatson
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    rwatson Senior Member

    Pure copper doesn't deter barnacles - so how does it antifoul ?

    The OP said that his copper rudder was covered in stuff, antifoul hull - not.
     
  9. michael pierzga
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    michael pierzga Senior Member

    Dont know. I just observe that copper sheathed components like the inside surface of a rudder skeg seem to stay cleaner . When a wood fishing trawler gets hauled the copper strap that connects anodes is reasonably clean. I think that growth doesn't like copper and stays off it until a film has been deposited then they make home on the film.
     
  10. michael pierzga
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    michael pierzga Senior Member

  11. Jacques B.
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    Jacques B. Junior Member

    Thanks Guys,

    From this I deduct that just because copper is supposed to be antibacterial doesn't mean it's antibarnacle.

    Here's what my rudder cladding looks like after barely 3 months in the water, and with the barnacles scraped-off of course. It went from pretty and pink (literally) to vert-de-gris agogo...
     

    Attached Files:

  12. michael pierzga
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    michael pierzga Senior Member

    A mass of underwater copper creates a galvanic corrosion problem.

    What did your anodes look like ?

    Is you copper connected to the ships earth or is it free standing ?

    Personally I would prime and paint the copper in the same way you paint a prop.

    And Remember..wood borers cant eat plastic... when they sink their teeth into plastic it gives them gas and all their friends abandon them

    Epoxy sheathed would be better than copper. ,
     
  13. Jacques B.
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    Jacques B. Junior Member

    There are 12 20-lb. rectangular anodes on the hull, and 2 little 4" dia. disc anodes on the rudder itself. The worst of the bunch is only missing about 5% of its original mass, but all of them were covered with a thin coat of white powder (zinc oxide?).

    The copper cladding is connected to the hull through the rudder hinges, so yes, I guess it's grounded.

    At this point, I'm going to try an epoxy primer + antifouling on the copper, and see what it looks like down the road. Hopefully, she won't be left sitting at dock for 3 straight months this time.

    Thanks again for your help!

    Jacques
     
  14. Markusik
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    Markusik Junior Member

    Sorry to bump old thread, but...

    The copper producers association, copper.org did extensive testing on antifouling properties of copper. I paraphrase their findings to say that copper works well provided it either spends some time at sufficient velocity to rub of some biofilm, and foremost it must be isolated from anodic protection.

    I've heard from CopperCoat users that when left stationary for some time, a gentle scraping is in order. Others report poor results, I suspect due to anodic protection.

    I'm curious to know how it works using outboards, without using sacrificial zincs.
     

  15. hoytedow
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    hoytedow Wood Butcher

    A properly maintained outboard will have sacrificial zincs in place.
     
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