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  • johnyrude200


    Replies: 782
    Topics: 186
    #3016

    So I brought up this topic in another thread and figured it is worthy of a separate line.

    I’ll be the first to admit that I cheated on my college chemistry exam just so I could graduate on time. And even with that, it was a coin flip for a few days as I held my breath to wait for final grades to come out. Although it is an interesting topic, it wasn’t one that I particularly enjoyed in my undergraduate years.

    That said – FrankR mentioned that the crystals aren’t what are so dangerous, rather, the corrosion the salt brings on.

    On that thought though, corrosion doesn’t happen until exposure to air. So after a day out at sea, if salt is rinsed off of the boat and motor (via flushing/hosing off), shouldn’t this retard corrosion or hopefully prevent it? I mean, flushing my motor for 10-15 mins after each salt use is about the only thing I can think of to be proactive.

    And how much does an anode help against corrosion from salt? I know it’s meant for stray electricity, but if memory serves correct, a lab we did back in the day (again, nearly 20 years ago), involved mixing salt into regular water and measuring reactivity/electrical conductivity differences. Obviously with salt, it had more conductivity.


    green-thumbs

    US Member - 2 Years
    Replies: 583
    Topics: 43
    #27422

    Corrosion and the prevention thereof is a large and complex subject that even the engineers
    sometimes get wrong. Metals tend to combine with other elements and compounds. Measures taken to prevent involve effort, expense and understanding. It is not unknown for effort and expense to be defeated by failure to understand.
    Years ago my mother overheated a stainless steel cook pot…after cleaning out the pot she
    poured in chlorine bleach to deal with black stain….overnight the stainless steel was pitted
    through to copper clad bottom…Revere ware stainless steel plus chlorine ions yum yum for
    corrosion. Stain in pot was unaffected.
    Louis


    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #27423

    Air is only part of the story. Dissimilar metals in an electrolyte are what batteries are made of. Dissimilar metals in salt water are what outboard motors are made of. Batteries produce electricity. So do outboard motors in such an environment. The electricity is what carries atoms (or parts of atoms) from here to there. That produces a change in the composition of the metals. The anode is supposed to provide an alternate path for the electricity to flow. (Yeah, right). And this whole explanation is an over simplification of the process, trying to put it in layman’s terms. I’m not a chemical engineer, just a lowly outboard mechanic on Florida’s Gulf Coast, where outboards dissolve overnight. Well, it takes some of them a couple of years.


    PugetSoundBoater


    Replies: 900
    Topics: 105
    #27426

    After running my motor in salt water, I barrel flush it with a 5% solution of a product called Salt Away, mfg’d in Ca . Helps dissolve salt buildup, but not the corrosion. The company claims this works better than just a flush with fresh water.

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    PugetSoundBoater


    Replies: 900
    Topics: 105
    #27428

    For further reading google electrolysis, galvanic corrosion ,dissimiliar metals. You will find many sites and forums concerning these topics. The technical lingo may tend to be overwhelming. NASA has a Corrosion Test Facility at Kennedy Space Center. Their website states that this location has the highest atmospheric corrosion levels of any location is the US. Wonder if they knew that when they built the place. They located the location there for the good weather for launching. This is a good thread,let’s keep it going.

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson

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