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Shaft Brush Failure

Discussion in 'Technical Discussion' started by PSW, Aug 3, 2017.

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  1. PSW

    PSW Member

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    In a trip right now and have been gone about a week. Getting ready to head back offshore tomorrow night. Doing checks in engine room today and found one had failed. I replaced them when I bought the boat 9 months ago. Look like it is a little delicate to me. It is the Pro Mariner. I have somebody bringing a new one tomorrow and a spare to keep on board. Thinking of going a different direction this winter if there is a better way to go. A pic of the failure and the other shaft that is still good.

    Thoughts?

    Attached Files:

  2. PSW

    PSW Member

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    *On a trip.
    Sorry my cell phone cropped pics like that. Click on the pic and the full image appears.
  3. d_meister

    d_meister Senior Member

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    Looks like it just corroded. Maybe saturate the lead with grease? The intact one and the surrounding area looks nice. Did the port side sling a lot of salt water at some time, and maybe run down the wiper shaft? Those wipers usually last forever or until someone steps on them.
  4. Capt J

    Capt J Senior Member

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    This. I would just install a new one and make sure saltwater isn't dripping on it. I would not put grease on it. Also it should be just touching the shaft, not pressed on it really hard.
  5. wdrzal

    wdrzal Senior Member

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    If that's lead solder (below the screw)and a acid base flux was used (for copper tubing) it will eat away at the wire connection. Electrical wire connections if soldered should use a rosin flux.
  6. Capt J

    Capt J Senior Member

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    Who soldered that tab where the bonding wire is mounted anyways? It can and should be attached where the wiper arm is attached on the other side of it near the other stringer.
  7. PSW

    PSW Member

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    Promariner. I have a green wire with end on it that I pace short bolt and connect to hole on shaft brush. Then I secure to bracket supplied by Cabo with 2 short bolts. No salt issues either in that area. Maybe when I attached when new it weakened the joint. Maybe a fluke. New brush on now and will monitor.

    Attached Files:

  8. Capt Ralph

    Capt Ralph Senior Member

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    I've installed these on a customers boat last year. Silver solder is used. Electric motor brushes used.
    The wire leads from the brush are normally flexible till stiffened with solder then brittle.
    Water may have helped but IMHO; vibration or chatter, to much contact pressure, maybe during install a lil twist was made for better contact or somebody has leaned / stepped on it.

    Remember why we don't like soldered connections on boats.

    On the other hand, in the old days just that copper finger was barely touching the shaft.

    Is there a bonding wire to the shaft log gland?
  9. wdrzal

    wdrzal Senior Member

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    The copper connecter between the screw and nut should have had the oxidation on the copper removed so you see shinny copper ,makes a better connection . Clean with sand paper, small wire brush, and steel wool works well too .

    rrapps if you do silver solder what percentage silver in the wire/rod do you use.?
  10. Capt Ralph

    Capt Ralph Senior Member

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    Silver solder is great. My comment was not to complain about the silver.
    But when you solder wires, then the wire is not flexible but rigid and fragile. Vibrations can now stress, crack and break that wire easily.
    The only way that brush was attached was under a taught pull of solder soaked, brittle wire.


    To try and expand again, This is why we don't like soldered connections on boats. Boats shake, vibrate and rattle.
    Flexible wire is only used. If soldered, it can break like a twig.
  11. Capt Ralph

    Capt Ralph Senior Member

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    Sense it's a non-serviceable brush assembly, May I recommend an idea that may help;
    On your next new brush assembly, use some thickened epoxy and build up a bead around the connection of the brush to the bar.
    Thus eliminating the stress on the soldered wire and making the component assembly more supportive and sealed.
  12. Capt J

    Capt J Senior Member

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    All of the ones I have seen and used, the brush has a stud that goes through the bar and a nut on the top side. You can either put the bonding wire terminal end also on this stud and just tighten the nut on it, OR put it on one of the bolts (holding the copper to the L bracket) that are closer to the stringer. Why would you have to or want to solder anything on this part is beyond the scope of my imagination. About the ONLY thing I solder on boats electrical anymore are wires smaller than 20 gauge, as it makes a more solid connection over butt connectors.
  13. wdrzal

    wdrzal Senior Member

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    rcrapps and all other contributors to the forum , I may ask a question like I did to rcrapps to keep the tread going to educate others.
    ,all
    Between copper and brass or stainless to stainless I would use 55% silver solder . There a a multitude of reason to too and not too solder. All covered many times previously. I didn't quote you Mr. rcrapps because instead of a line like "we all know the reasons not too" there are thousands of readers that weren't here when that topic was coverer dozens of times before. Repeat it again and keep on educating new readers. I know there a search function but many never use it.

    rcrapps its apparent to me you have a wealth of knowledge and first hand experience, I respect all 4,562 of your posts. Let's keep on teaching others. Isn't that what this section of the forum is for ?

    Walt
  14. wdrzal

    wdrzal Senior Member

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    In the above post I paraphrased and shouldn't have used quotation marks. Mr rcrapps. said "Remember why we don't like soldered connections on boats" my bad.

    I'm in my electronics lab looking at the inside of a combustion analyzer my brain is overloaded, wish I was getting loaded.
    Last edited: Aug 6, 2017
  15. PacBlue

    PacBlue Senior Member

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    The bigger question that seems to be overlooked - do you really need shaft wipers?
  16. Capt J

    Capt J Senior Member

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    Absolutely. Boats that have shaft wipers don't use zincs on the shafts, so the wipers tie the running gear into the bonding system and transom zinc. Not having shaft zincs provides more water flow to the propellors (uninterrupted), cutlass bearings, and less drag
  17. Capt Ralph

    Capt Ralph Senior Member

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    I remember a SeaRay with Cat diesels, TD V drive. Diver reported one of the bronze props was getting burned for some unknown reason.
    No zincs on the shafts as SeaRay usually does.
    I found Low DC voltage between the engine and stainless shaft.
    After installing a set of brushes, all was Zero.
    Later that shaft got clobbered and pulled. There was a layer of brown stain, near dialectic, blocking current from the clutch coupler to the shaft.
    I feel these brushes are cheap insurance keeping stray currents down from/to the running gear. Old bronze gland logs need to be bonded also.
  18. Marmot

    Marmot Senior Member

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    So they had a difference of opinion?
  19. Capt Ralph

    Capt Ralph Senior Member

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    Hello there ole friend.
    Yep, Some kind of difference. Near enough for almost 1/2 volt and Ks of resistance.
    Near the effort of my first wife.
  20. PSW

    PSW Member

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    After replacing and putting another 350nm on the boat I checked both when I returned home. Appears there is too much pressure and the shaft and it breaks over time.. I released some pressure but will move to a more secure set up this winter. Another Cabo owner sent pics of his 43 shafts and they are different. These work but are not the best brushes IMO.