Results 1 to 12 of 12

Thread: use zinc anode on boat trailer

  1. #1
    Join Date
    Jun 2011
    Location
    Hard Scrabble, MS
    Posts
    428

    Default use zinc anode on boat trailer

    use zinc anode on boat trailer
    I live 400 miles away from salt water. Boat trailers are usually painted steel, and not galvanized, where I live, North Alabama.
    Painted steel rusts even thought I live far from salt water.
    ? If I attached a zinc anode to my trailer, would it reduce corrosion ?
    ? Does the zinc anode only work if the trailer is in the water ?
    Zinc anodes are magic to me.

  2. #2
    Join Date
    Oct 2009
    Location
    South Puget Sound/summer Eastern carib./winter
    Posts
    18,552

    Default Re: use zinc anode on boat trailer

    I think zinc is not used in freshwater.
    magnesium

  3. #3
    Join Date
    Mar 2007
    Location
    East Quogue,NY
    Posts
    20,899

    Default Re: use zinc anode on boat trailer

    Sacrificial anodes--which may be made of zinc, magnesium or aluminum--do not prevent or inhibit rust. They work to offset the effect of galvanic action, which occurs when two dissimilar metals are immersed in an electrolyte. So, no, mounting a zinc will not prevent your trailer from rusting.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  4. #4
    Join Date
    Jun 2000
    Location
    Pleasant Valley NS Canada
    Posts
    21,345

    Default Re: use zinc anode on boat trailer

    ^ What he said...
    Hope for the best, but plan for the worst.

  5. #5
    Join Date
    Oct 2008
    Location
    Walney, near Cumbria UK
    Posts
    51,283

    Default Re: use zinc anode on boat trailer

    ^ Yep. The only effective preventative is a good paint system or galvanising.
    Are there no galvanising tanks near you?
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

  6. #6
    Join Date
    Jan 2001
    Location
    St. Simon\'s Island, GA, USA
    Posts
    5,861

    Default Re: use zinc anode on boat trailer

    There is also zinc rich paint, at your Ace Hardware. I have never put it the test. Anyone else?

  7. #7
    Join Date
    Jun 2003
    Location
    Central Coast, Ca
    Posts
    29,201

    Default Re: use zinc anode on boat trailer

    I have used quite a bit of Zinc paint, many gallons in fact.
    It works just fine.

    https://www.fastenal.com/products/details/0132059

  8. #8
    Join Date
    Jun 2011
    Location
    Hard Scrabble, MS
    Posts
    428

    Default Re: use zinc anode on boat trailer

    Quote Originally Posted by Breakaway View Post
    Sacrificial anodes--which may be made of zinc, magnesium or aluminum--do not prevent or inhibit rust. They work to offset the effect of galvanic action, which occurs when two dissimilar metals are immersed in an electrolyte. So, no, mounting a zinc will not prevent your trailer from rusting.
    Kevin
    I'm missing something here. I thought Zinc coated tin roofs seem to slow down rust.

  9. #9
    Join Date
    Mar 2018
    Location
    Annapolis, MD, USA
    Posts
    60

    Default Re: use zinc anode on boat trailer

    Quote Originally Posted by Bluegill View Post
    I'm missing something here. I thought Zinc coated tin roofs seem to slow down rust.
    They do indeed. But "a zinc" is different from a zinc coating.

    "A zinc" is a chunk of metallic zinc bolted onto assorted underwater metal parts of a boat. It might be bolted to a strut or a steel rudder; a zinc collar might be bolted to a prop shaft; or a zinc nugget might be attached to an outdrive or the lower unit of an outboard. In the world of electrolysis, zinc erodes away faster than the metal bits it's bonded to. So these zincs are sacrificial: electrolysis eats away the zincs rather than the metal parts you care about. You have to replace the zincs periodically before they're gone. Otherwise electolysis will attack the parts the zincs had been protecting. Usually the zincs are sized so you replace them once a year when you pull the boat to repaint the bottom.

    In contrast a zinc coating covers the entire surface of the piece it's protecting. The coating is a barrier to the elements. Metal paint, if you will. But it lasts much longer than paint because ultraviolet rays and ozone can't attack it. Hence zinc-coated metal roofs, fences, etc. last much longer without re-coating than painted ones.

  10. #10
    Join Date
    Jun 2011
    Location
    Hard Scrabble, MS
    Posts
    428

    Default Re: use zinc anode on boat trailer

    Quote Originally Posted by Chenier View Post
    They do indeed. But "a zinc" is different from a zinc coating.

    "A zinc" is a chunk of metallic zinc bolted onto assorted underwater metal parts of a boat. It might be bolted to a strut or a steel rudder; a zinc collar might be bolted to a prop shaft; or a zinc nugget might be attached to an outdrive or the lower unit of an outboard. In the world of electrolysis, zinc erodes away faster than the metal bits it's bonded to. So these zincs are sacrificial: electrolysis eats away the zincs rather than the metal parts you care about. You have to replace the zincs periodically before they're gone. Otherwise electolysis will attack the parts the zincs had been protecting. Usually the zincs are sized so you replace them once a year when you pull the boat to repaint the bottom.

    In contrast a zinc coating covers the entire surface of the piece it's protecting. The coating is a barrier to the elements. Metal paint, if you will. But it lasts much longer than paint because ultraviolet rays and ozone can't attack it. Hence zinc-coated metal roofs, fences, etc. last much longer without re-coating than painted ones.
    Thanks, I needed that.

  11. #11
    Join Date
    Aug 2005
    Location
    SF Bay Area- Richmond
    Posts
    16,412

    Default Re: use zinc anode on boat trailer

    No.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  12. #12
    Join Date
    Dec 2003
    Location
    MA
    Posts
    405

    Default Re: use zinc anode on boat trailer

    Quote Originally Posted by Chenier View Post
    They do indeed. But "a zinc" is different from a zinc coating.

    "A zinc" is a chunk of metallic zinc bolted onto assorted underwater metal parts of a boat. It might be bolted to a strut or a steel rudder; a zinc collar might be bolted to a prop shaft; or a zinc nugget might be attached to an outdrive or the lower unit of an outboard. In the world of electrolysis, zinc erodes away faster than the metal bits it's bonded to. So these zincs are sacrificial: electrolysis eats away the zincs rather than the metal parts you care about. You have to replace the zincs periodically before they're gone. Otherwise electolysis will attack the parts the zincs had been protecting. Usually the zincs are sized so you replace them once a year when you pull the boat to repaint the bottom.

    In contrast a zinc coating covers the entire surface of the piece it's protecting. The coating is a barrier to the elements. Metal paint, if you will. But it lasts much longer than paint because ultraviolet rays and ozone can't attack it. Hence zinc-coated metal roofs, fences, etc. last much longer without re-coating than painted ones.



    That isn't exactly right...not trying to be mean, but the purpose of zinc plating (hot dip or electrolytic) or zinc paint to to provide protection in case of a scratch that goes through to the base steel. In that scenario there are two dissimilar metals along the scratch and the zinc oxidizes preferentially to the steel. If I remember correctly zinc forms a tenacious oxide layer, while iron expands and becomes brittle and expands when it oxidizes...exposing more fresh iron own below.

    That is why you coat steel with zinc. Back in the day when cars had paint over bear metal, a scratch through the paint would begin to rust in a few days...but today even if the scratch goes through the zinc layer...it is protected.

    Russell.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •