Click for Cheoy Lee Click for Seacoast Click for Westport Click for United Click for Dockmate

Galvanic isolator

Discussion in 'Post Yacht' started by My Affair, Mar 21, 2020.

You need to be registered and signed in to view this content.
  1. My Affair

    My Affair Member

    Joined:
    May 23, 2006
    Messages:
    94
    Location:
    Mystic, CT
    my 1975 42 Post had a galvanic isolator located on the forward bulkhead of the engine room. I cannot locate one on my 1988 46 Post. Did they discontinue using one and does anyone know why?
  2. Davidoc

    Davidoc Senior Member

    Joined:
    Aug 29, 2005
    Messages:
    210
    Location:
    Winter:Delray Beach, Fl Summer: Bahamas
    None came on my 91-46. I quickly put one on after I bought the boat. It's been a real asset. Installed it behind the breaker panel with remote indicator.
  3. My Affair

    My Affair Member

    Joined:
    May 23, 2006
    Messages:
    94
    Location:
    Mystic, CT
    Hi Where did you locate the isolator? Where did you tie in the wiring? Do you have photo available? Thanks
  4. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    8,000
    Location:
    Satsuma, FL
    Any where in the green wire before the shore service outlet.
    Are you sure you do not have one already? Are you sure you need one?
  5. Davidoc

    Davidoc Senior Member

    Joined:
    Aug 29, 2005
    Messages:
    210
    Location:
    Winter:Delray Beach, Fl Summer: Bahamas
    The other end of the isolator goes to the DC ground for the bonding system. Just key in marine isolaters on google and look for a 50 amp device then pull up the installation instructions and you'll see the wiring diagram it's pretty straight forward and behind the breaker panel is probably the easiest place to find both grounds the AC green wire ground and the DC bonding system ground. I can send you a picture for a week or so not near the boat right now
  6. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    8,000
    Location:
    Satsuma, FL
    I don't think the galvanic isolator is connected to the ships bonding. Just in-line on the ships shore service green (fault current) wire.
  7. cleanslate

    cleanslate Senior Member

    Joined:
    May 29, 2018
    Messages:
    607
    Location:
    Cherry Hill, NJ
    Capt Ralph, It's me! I'm back. Did you miss me? Lol.
    Playing around my bilge last week cleaning with Spray Nine and MANY rags , I noticed both my DC ground and bonding ground where grounded to a stud/bolt on the bocks of my Detroits . From the looks of it, it was clear to me this was original work done by Ocean Yachts at the factory.
    I did not think the bonding should be tied into the motors or DC system?
    What's wit that?
  8. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    8,000
    Location:
    Satsuma, FL
    Without DCv isolated alternators, starters and other options, it would be impossible to isolate DCv from the ships bonding system.
    So, Yes; Not to be used for powering options the bonding system and DCv- are tied together.

    It is stray DCv currents that we want to stop between your boat and others thru the water while commonly connected with dock service green wires.

    Usually, the ships green wire (ACv fault current) is not tied to the bonding system while on shore service.

    The O P is talking about a galvanic isolator. This keeps DCv currents from passing thru the shore power service (on the green wire) to commonly connect other boats. Your boat and the boat next door connected by the same green wire can form a path thru the water side of the circuit and lead to galvanic erosion (think wet battery and the boats are the plates).
    Last edited: Mar 22, 2020
  9. cleanslate

    cleanslate Senior Member

    Joined:
    May 29, 2018
    Messages:
    607
    Location:
    Cherry Hill, NJ
    Ok got it, I do seem to have something going on. My zincs seem to getting ''Ett'' up a bit to fast. That being said , I know of one bonding wire that forward that seems to tie in the port and starboard wire run aft that is gone from hanging in the bilge water. I will be fixing that soon while I'm out of the water.

    I will look behind my panel for one of those 1981 vintage isolator. I assume it will be quite large if I have one? 10''x6'' or so?
  10. My Affair

    My Affair Member

    Joined:
    May 23, 2006
    Messages:
    94
    Location:
    Mystic, CT
    Mine was behind the generator and about 6x8 and was blue in color
  11. chesapeake46

    chesapeake46 Senior Member

    Joined:
    Jul 26, 2009
    Messages:
    1,339
    Location:
    Chesapeake Bay, Delaware Bay & S.Jersey
    1980 - 46 - no isolator
  12. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    8,000
    Location:
    Satsuma, FL
    If it's an old unit, replace it anyway.
  13. postyachts139

    postyachts139 New Member

    Joined:
    Dec 30, 2017
    Messages:
    3
    Location:
    ny
    mine is behind electrical panel on 7 43 post
  14. cleanslate

    cleanslate Senior Member

    Joined:
    May 29, 2018
    Messages:
    607
    Location:
    Cherry Hill, NJ
    I have another question. How about while at anchor/underway when the generator is on should I also have a galvanic isolator on the green wire between the Gen. and the selector switch?
  15. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    8,000
    Location:
    Satsuma, FL
    No, You are not sharing the green wire with another boat.
  16. cleanslate

    cleanslate Senior Member

    Joined:
    May 29, 2018
    Messages:
    607
    Location:
    Cherry Hill, NJ
    I knew that...I was just testing you.:rolleyes:

    Thank You.
  17. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    11,871
    Location:
    Fort Lauderdale
    I usually install them really close to where the shorepower cord attaches to the boat. Many times you need to add wire, so it's easier to take it off of the boat side where it attaches to the cord or receptacle, run it to one side of the isolator, and then a new wire to attach to the cord end.