Page 1 of 5 12345 LastLast
Results 1 to 15 of 63

Thread: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

  1. #1

    Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    I am asking for a friend.😉
    A more simple question as some people get confused easily
    Hypothetically.
    A stainless-steel propeller is attached to an aluminium alloy power head by a drive shaft.
    The hot seawater from the alloy power head exits the motor through the stainless propeller hub.
    Galvanic corrosion occurs when dissimilar metals are connected by an electrolyte.
    An example of a marine alloy from Mercury Marine Engines contains tin, copper, zinc, copper, and aluminium
    316 Stainless contains iron, chromium, nickel and molybdenum.
    What could go wrong?

  2. #2

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.


  3. #3

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by Bobpen View Post
    I am asking for a friend.😉
    A more simple question as some people get confused easily
    Hypothetically.
    A stainless-steel propeller is attached to an aluminium alloy power head by a drive shaft.
    The hot seawater from the alloy power head exits the motor through the stainless propeller hub.
    Galvanic corrosion occurs when dissimilar metals are connected by an electrolyte.
    An example of a marine alloy from Mercury Marine Engines contains tin, copper, zinc, copper, and aluminium
    316 Stainless contains iron, chromium, nickel and molybdenum.
    What could go wrong?
    Ok for my edification as I am simple and easily confused, if the prop hub is SS and it is sitting on a SS shaft how does that exacerbate the so called galvanic reaction that is occurring. Now I do remove my prop regularly and surprisingly there is still always a coating if grease in the splines, maybe that's causing the problem.

  4. #4

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Only if you unbolt them both and put them in a jar of electrolyte on your bedside table. 🤦

    PS - make sure to unbolt the anodes first or you won't get the desired result

  5. #5

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by scottar View Post
    Only if you unbolt them both and put them in a jar of electrolyte on your bedside table. 臘

    PS - make sure to unbolt the anodes first or you won't get the desired result
    It is hard to use the boat with the propeller off.
    Have you ever used a boat?

  6. #6

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by scottar View Post
    Only if you unbolt them both and put them in a jar of electrolyte on your bedside table. 臘

    PS - make sure to unbolt the anodes first or you won't get the desired result
    The sea water is an electrolyte. Look it up.
    When I use the motor it is sea water.
    Is there anyone else out there?

  7. #7

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by Dignity View Post
    Ok for my edification as I am simple and easily confused, if the prop hub is SS and it is sitting on a SS shaft how does that exacerbate the so called galvanic reaction that is occurring. Now I do remove my prop regularly and surprisingly there is still always a coating if grease in the splines, maybe that's causing the problem.
    The stainless propeller is connected electrically to the power head through the drive shaft it has a giant nut holding it on.
    The power head is alloy.
    The alloy power head then connects to the stainless propeller though the hot seawater electrolyte which leaves though the stainless propeller hub with the exhaust gases.
    The dissimilar metals cause galvanic corrosion.
    Simples.,

  8. #8

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    The seawater comes into the motor before the propeller so the two aren't connected by electrolyte. In any case the motor isn't running for more than 50 - 100 hours a year for most recreational use which is not a lot of time for corrosion to occur.

  9. #9

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by billfisher View Post
    The seawater comes into the motor before the propeller so the two aren't connected by electrolyte. In any case the motor isn't running for more than 50 - 100 hours a year for most recreational use which is not a lot of time for corrosion to occur.
    The hot sea water from the alloy power head exhausts through the stainless propeller.
    A direct connection.
    I worked out my boat was in seawater for about 1,600 hours before there was enough corrosion to destroy the engine mounts.
    Most of those hours the boat was at anchor but the motor was still full of sea water probably still warm.
    Anyone else out there?

  10. #10

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Great thread

    DoNotFeedTheTrollsAandBelligerent

  11. #11

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by Bobpen View Post
    The stainless propeller is connected electrically to the power head
    This has me totally flummoxed, how?

  12. #12

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Is you're "friend" a "nut" that holds the propeller on? I had to clarrify before disorderly calls me a useless tool

  13. #13

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by Bobpen View Post
    It is hard to use the boat with the propeller off.
    Have you ever used a boat?
    So get a bigger jar and put the whole motor in if you don't want to take the prop off. Do I have to think of everything Bob??????

    I only use my boat occasionally .......... you got me there. The rest of the time I have to work..........maintaining a fleet of commercial vessels..............made up of dissimilar metals including aluminium, steel bronze, stainless, copper nickel, cast iron and probably a few others.............that get stored in a giant puddle of electrolyte..............by changing the anodes which protect them against galvanic corrosion among other things...............who would have thought huh.


    You are right though Bob........some people do get confused easily.

  14. #14

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by gazza2006au View Post
    Is you're "friend" a "nut" that holds the propeller on? I had to clarrify before disorderly calls me a useless tool
    Ha ha, Gazza, I think in this case Disorderly would be laughing alongside with you. I suspect this is a Troll post, especially when he queries whether Scottar who works and spends his off time on the water whether he has been on a boat is laughable.
    I actually sent the copy of all these posts to a scientist mate who specialises in metallurgy and has spent 2 seasons in the Antarctic so no fool and he just laughed and did say some rather harsh things and said I was being had, so I'll stop commenting now.

    Edit: I see Scottar got in before me.

  15. #15

    Re: Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

    Quote Originally Posted by Bobpen View Post
    The hot sea water from the alloy power head exhausts through the stainless propeller.
    A direct connection.
    I worked out my boat was in seawater for about 1,600 hours before there was enough corrosion to destroy the engine mounts.
    Most of those hours the boat was at anchor but the motor was still full of sea water probably still warm.
    Anyone else out there?
    interesting you never mentioned your boat was moored in your other thread!

Posting Permissions

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