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  1. #1
    Join Date
    Jan 2012
    Location
    South Coast
    Posts
    5,229

    Default A somewhat pink prop !

    Looks like I will be buying a new Starboard prop this Winter.

    All due to a corroded, but only 2 year old shaft brush with an 80 ohm resistance between the carbon face touching the shaft and the brush holder itself.

    0 ohms between the rudder and the zinc, hence the lovely brass colour.

    Heyho !

    Interested in Corvettes PM me for details of the Corvette Motorboat Association

  2. #2
    Join Date
    Jul 2014
    Location
    Sail on the Medway, Kent from Chatham Maritime Marina
    Posts
    1,944

    Default Re: A somewhat pink prop !

    It certainly looks pretty in pink!
    If my foresight was as good as my hindsight, I would be a multi-millionaire.

  3. #3
    Join Date
    Jun 2001
    Location
    UK East Coast
    Posts
    1,898

    Default Re: A somewhat pink prop !

    Quote Originally Posted by superheat6k View Post
    Looks like I will be buying a new Starboard prop this Winter.

    All due to a corroded, but only 2 year old shaft brush with an 80 ohm resistance between the carbon face touching the shaft and the brush holder itself.

    0 ohms between the rudder and the zinc, hence the lovely brass colour.

    Heyho !

    Is that nose-cone a zinc anode?

    Www.solocoastalsailing.co.uk

  4. #4
    Join Date
    Nov 2001
    Location
    Medway
    Posts
    20,141

    Default Re: A somewhat pink prop !

    Quote Originally Posted by Plum View Post
    Is that nose-cone a zinc anode?

    Www.solocoastalsailing.co.uk

    been there.

    Couple of big pairs of S/H props of ebay.
    Might be worth a look , with bit of tweaking from your local propshop might save a bit ?

  5. #5
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    43,715

    Default Re: A somewhat pink prop !

    Quote Originally Posted by superheat6k View Post
    Looks like I will be buying a new Starboard prop this Winter.

    All due to a corroded, but only 2 year old shaft brush with an 80 ohm resistance between the carbon face touching the shaft and the brush holder itself.

    0 ohms between the rudder and the zinc, hence the lovely brass colour.

    Heyho !
    Vyv always says that a zinc anode wii not prevent dezincification,

    If he is correct you will need to consider the possibility that there is some reason, other than the corroded shaft brush, for the condition of your prop

  6. #6
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    22,043

    Default Re: A somewhat pink prop !

    Quote Originally Posted by VicS View Post
    Vyv always says that a zinc anode wii not prevent dezincification,

    If he is correct you will need to consider the possibility that there is some reason, other than the corroded shaft brush, for the condition of your prop
    Yes, the zinc phase in brass or manganese bronze contains a very small proportion of copper, so the voltage between it and a zinc anode will be very small indeed. Very limited protection is provided. My anode-bonded P-bracket dezincified quite badly. I dumped the anode and painted the replacement P-bracket.
    Answers to some technical queries at new website http://coxeng.co.uk

  7. #7
    Join Date
    Feb 2008
    Location
    Farndon
    Posts
    3,117

    Default Re: A somewhat pink prop !

    Quote Originally Posted by superheat6k View Post
    Looks like I will be buying a new Starboard prop this Winter.

    Outdrives might perhaps less trouble😁

    Is there a concern the propeller may be structurally unsound ?

  8. #8
    Join Date
    Jan 2012
    Location
    South Coast
    Posts
    5,229

    Default Re: A somewhat pink prop !

    Quote Originally Posted by MartynG View Post
    Outdrives might perhaps less trouble

    Is there a concern the propeller may be structurally unsound ?
    I would love to have out drives, but unfortunately I can't until the hole in my bottom heals over, you see this was a solemn promise to myself many many moons ago !

    The port prop is fine and the high resistance across the shaft brush was definitive. The bonding to the P Bracket and rudder is fine, so I ma satisfied the problem is located.

    I am fitting PSS seals to replace the stuffing boxes, so hopefully a drier environment around the brushes in future. I have noticed there are also bonding cables across the plastic R&D shaft couplings so it looks like these have also failed. The couplings reside in something of a black hole, and it is only now I have properly examined them ready for dismantling and removing the couplings so I can pull the shafts out.

    I will have a look at Ebay for the prop listings, thanks.
    Interested in Corvettes PM me for details of the Corvette Motorboat Association

  9. #9
    Join Date
    Feb 2003
    Posts
    15,747

    Default Re: A somewhat pink prop !

    Quote Originally Posted by superheat6k View Post
    Looks like I will be buying a new Starboard prop this Winter.

    All due to a corroded, but only 2 year old shaft brush with an 80 ohm resistance between the carbon face touching the shaft and the brush holder itself.

    0 ohms between the rudder and the zinc, hence the lovely brass colour.

    Heyho !

    Before lashing out I would get a file and file a small portion in a sage place, I would bet that that dezincification isnt as deep as you think it is!
    I had a thru hull that looked that bad, after I changed it I hacksawed it through, the pink bit was only skin deep!
    ,

  10. #10
    Join Date
    Jun 2001
    Location
    UK East Coast
    Posts
    1,898

    Default Re: A somewhat pink prop !

    Quote Originally Posted by vyv_cox View Post
    Yes, the zinc phase in brass or manganese bronze contains a very small proportion of copper, so the voltage between it and a zinc anode will be very small indeed. Very limited protection is provided. My anode-bonded P-bracket dezincified quite badly. I dumped the anode and painted the replacement P-bracket.
    Interesting. So are you saying protecting brass/manganese bronze props with a zinc anode is not necessary?

    Www.solocoastalsailing.co.uk

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