Zincs: yes or no?

Discussion in 'General Discussion' started by bayboatersf, Jul 24, 2013.

  1. bayboatersf

    bayboatersf New Member

    36
    Jun 29, 2012
    San Francisco
    2000 Sea Ray 380
    Mercruisers 8.1
    I had conflicting opinions on having zincs around the shafts on my Sea Ray 380. The Sea Ray people say that I don't need them because the way the boat has been wired while the mechanic says I should have them.
    Please advise.
    Thanks
     
  2. Dsybok

    Dsybok New Member

    388
    Jul 9, 2011
    Los Angeles/Lakewood, CA
    Currently Boatless
    Boatless
    My boat yard actually installed shaft zincs on my 320DA when I last hauled but when they wore out I had my diver remove them. According to the manual the shafts are bonded and therefore the transom zinc should be all that you need. I decided the slight increase in drag / weight was not worth the possible minute increase in corrosion protection.

    So thus my boat has one large rectangular transom zinc and individuals on each trim tab. Seems to be doing fine. I would trust Sea Ray, your mechanic may not fully understand your boat's inherent protection and its just added cost you probably don't need.
     
  3. Bluto310

    Bluto310 New Member

    14
    Jul 30, 2012
    Panama City, FL
    310 Sundancer '99
    350 MAG MPI, V-Drives
    My mechanic suggested shaft zincs and I added them about 4 years ago. Cheap insurance in my opinion, even with a good bonding system. I use U.S. made Camp zincs and have been getting around a year to year and a half out of them.
     
  4. rcknecht

    rcknecht Active Member

    Mar 23, 2009
    toms river,nj
    340 Sundancer 2001
    T 454 MPI
    I put them on my boat, and every year they are gone... I would put them on if you boat in salt water... More is better, IMHO
     
  5. Irie308

    Irie308 Member SILVER Sponsor

    701
    May 28, 2013
    CT
    320 Sundancer 2005, Raymarine C120 and C80
    Highfield 9.6 RIB & Tohatsu 8hp
    Previous boat: 215 expre
    350 Mercruisers V-drives
    Stupid question here...but can someone explain the need for "Zincs". I'm not sure if my boat has them or needs them...so i'm a bit worried as its our first season on the water and I had no clue at the time what zincs were. We are docked on the Housatonic river in CT and boat in the Sound as well.
     
  6. trit21

    trit21 New Member

    Dec 16, 2007
    Live, Orlando: Boat, Ft. Pierce
    See signature
    See signature
  7. Dsybok

    Dsybok New Member

    388
    Jul 9, 2011
    Los Angeles/Lakewood, CA
    Currently Boatless
    Boatless
    Sure, this will explain the basics for you: http://www.boatus.com/boattech/casey/sacrificial-zincs.asp

    You need "zincs" whether in fresh or saltwater, but you need to make sure you get the right material and size for your boat and waters that you boat in, which for you is probably zinc or aluminum.

    In a nutshell when you have multiple metals exposed to water the less noble metal will tend to corrode faster because of the galvanic corrosion effect, so if you put an even lesser metal such as zinc or magnesium on your boat, it will corrode first, thus protecting the other metals, the stainless steel in your shafts or bronze props or rudders etc, all the expensive stuff.

    If you don't use zincs, your other more valuable boat parts will corrode instead. Zincs are cheap, outdrives or running gear are not.
     
  8. jeffk

    jeffk New Member

    273
    Apr 28, 2009
    Sarasota, Florida
    2006 300 Sundancer
    5.0L Mercruiser w/Bravo III
    ""Zincs are cheap, outdrives or running gear are not"" 2nd that!!!
     
  9. BritLady

    BritLady Active Member

    Jul 30, 2011
    FL West Coast
    2006 - 340 SeaRay Sundancer, Garmin 840XS GPS & Garmin 7401XS GPS
    2013 - Mercury 280 RIB Dink 8'10"
    Inboard 8.1 Horizon Mercruiser & 2015 6HP Tohatsu O/B.
    We recently had our diver replace our transom zincs (he replaces the shaft zincs more regularly). Transom zinc lasted about 18 months, he said it was down to about 8oz and started out about 8/9Lbs! Better them than the other metal "stuff":)
     
  10. trit21

    trit21 New Member

    Dec 16, 2007
    Live, Orlando: Boat, Ft. Pierce
    See signature
    See signature
    Your divers isn't doing a very good job as they are supposed to replaced after 50% of the start weight. But then again, that is kind of a waste of money but I think they allowed it to go a little too long. You were down to 1/2lb.
     
  11. BritLady

    BritLady Active Member

    Jul 30, 2011
    FL West Coast
    2006 - 340 SeaRay Sundancer, Garmin 840XS GPS & Garmin 7401XS GPS
    2013 - Mercury 280 RIB Dink 8'10"
    Inboard 8.1 Horizon Mercruiser & 2015 6HP Tohatsu O/B.
    He doesn't usually let them get that low, generally 2/3 but he's been sick and could not dive for awhile and we could not get out due to work and bad weather. We didn't like to get anyone else as he's a retired Vet with one leg so like to keep him employed while he can still do it.
     
  12. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    What would be the downside of putting them on?
     
  13. trit21

    trit21 New Member

    Dec 16, 2007
    Live, Orlando: Boat, Ft. Pierce
    See signature
    See signature
    Downside is too much zinc. Look at post #6 and follow the link and determine if you have too much zinc for you application.
     
  14. Dsybok

    Dsybok New Member

    388
    Jul 9, 2011
    Los Angeles/Lakewood, CA
    Currently Boatless
    Boatless
    Another downside is they can come loose over time, slip and cause vibration when you run. If I don't have to add something to a part of my boat that is revolving at a very fast rate, I would prefer not to. Plus, ok, its only a few pounds, but its also extra weight you are carrying around. Lastly, if you don't really need them, you're spending $30 or $40 bucks 2-3 times a year to replace something you don't really need. That's a nice steak dinner somewhere with the Admiral.
     
  15. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    From the boatzincs website:

    Overprotection usually occurs from one the following conditions:

    • Using the wrong type of anodes (e.g., magnesium anodes in saltwater);

    • A defective impressed-current corrosion controller;

    • Stray DC currents originating from defective wiring or equipment within
    your vessel.


    If everything is correct, than I guess I must be missing something........
     
  16. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    I use Loctite on the threads and never have a problem with a zinc vibrating loose, but admittedly none of my zincs are mounted on a rotating assembly below the waterline. I do see lots of boats with them mounted on shafts, and never really heard a lot of complaints about them coming loose. I guess if it did vibrate loose from the shaft it could do some damage to the prop.
     
  17. trit21

    trit21 New Member

    Dec 16, 2007
    Live, Orlando: Boat, Ft. Pierce
    See signature
    See signature

    Ok, let me sum it up for you. Using a silver/silver chloride reference electrode connected to a DMM, you determine the voltage from the page I referenced. You then look at the chart on that page and determine if you underprotected or overprotected. If under, then you should add more zinc, if over then "Overprotection usually occurs from one the following conditions:". They are not expecting someone of just add zinc for no reason. Usually people just put back on what the manufacturer has started. But if you have too much protection, ie too much zinc, you will also get an abnormal higher than normal reading.

    Overprotection can create conditions that damage underwater hull coatings, aluminum alloy metals and wooden hulls.
    • Steel and fiberglass hulls -- decreased effectiveness of anti-fouling
    paints and barrier coatings when made more negative than -1100 mV.

    • Aluminum hulls and outdrives -- highly susceptible to alkali corrosion of
    its metal, and hydrogen blistering of its paint coatings, when made more
    negative than -1200 mV.

    • Wooden hulls -- destruction of wood fibers (alkali delignification) occurs
    around metal fittings made more negative than -650 mV.


    Overprotection occurs in many ways and by adding zinc then you are in an overprotected situation.
     
  18. Dsybok

    Dsybok New Member

    388
    Jul 9, 2011
    Los Angeles/Lakewood, CA
    Currently Boatless
    Boatless
    You may install them properly, but a lot of boats by necessity have to have them installed while the boat is in the water, not sure if you can use loctite under those conditions and they will also be installed by a diver who is probably not going to be as careful as the boat owner. A few guys at my marina have told me they hauled their boat at one point and their shaft zincs were just gone, and not from wear, they just fell off at some point. That would scare me, prop damage is expensive to remedy, and even a little ding can ruin your boat's performance.
     
  19. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Under those circumstances I would probably skip them too if I could. When I put them on my boat I know they are installed properly and the surfaces underneath cleaned correctly. The fasteners are tightened with Loctite, and I know they aren't coming off from vibration.
     
  20. bayboatersf

    bayboatersf New Member

    36
    Jun 29, 2012
    San Francisco
    2000 Sea Ray 380
    Mercruisers 8.1
    Thanks for your comments. Yesterday I had the zincs removed. It could be just a mental thing, but I feel better thinking that, running at 4,000 rpm they could have come off.
     

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