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    Serious Stray Current Corrosion, need advice

    Yeah, wasn't expecting to find this when I hauled the boat. I'm pretty fastidious when it comes to cleaning and inspecting my bottom since I do it myself. I put a new transom zinc on and shaft zincs in the middle of this summer. The previous transom zinc had lasted 2 years and the shafts zincs over a year (and only one had fallen off). I never noticed anything unusual with my running gear during that time or previous times. I did slack on diving on the boat so it accumulated growth (mostly soft) from about August till January when I hauled it for winter. I'm sure this damage happened during this time. I'm glad that I hauled when I did!

    Looking at the pictures, you can see a pink sheen starting on the struts, rudders (spotty), and the outer most trim tabs are eaten up. I think the stray current is coming from the starboard side and working it's way across the bonding system. There is a heavy black wire attached to the stud where the big hole is eaten thru the tab. The starboard trim tab is the most heavily eaten up. The transom zinc and shaft zincs have that shiny crystal look to them which I think is electrical in nature. Props are fine. Thru hulls are fine. See pictures.

    Any advice on what that black wire goes to? Or where to start on this adventure? I'm kind of floored to find this damage, but glad I found it now and not this summer along with a loss of everything under water

    Thanks!
    Attached Files
    . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

    #2
    I can't help with your challenges but I can add that I too have had problems with my 3870. The outside starboard trim tab was eaten to the point that the lower planning piece fell off while passing through some rapids shortly after I purchase the boat in 2016. The PO never had any zincs on the tabs. I replaced the tab with a new one in the fall of 2016 and added zincs to all four tabs. I have replaced my zincs every year. On doing the bottom in 2019 I found this 'new' tab was again showing serious signs of electrolysis even with the zinc in place and appearing to be working - sacrificing? The other three tabs and all other metal looked fine.

    It may be stray current from the boat I am moored beside in the next slip in my marina? He is a live aboard and the boat has not been out of the water in years. But he is moored on my port side and my problem appears to only be on my starboard tab? I also have a part time live aboard on my starboard side slip but this fellow seems to take care of his vessel?

    My boat has a zinc saver (name on it) under the dash that looks original. I have no idea if it is working or how to test same? My shore power seems to be OK.
    16' lap straight with B&S inboard, my 1st commercial fishing adventure
    17' run about with original 80ph Volvo, fun with some exploration of the coast
    25' Chris Craft - lots of fun exploring further north on the BC coast
    32' wood commercial salmon troller - ice boat, hard work & fun
    41' wood commercial salmon troller - ice boat, hard work & fun
    38' Permaglass commercial salmon troller - freezer boat, harder work & fun
    1987 3870 with 175 Hinos - back to mostly fun again & exploration

    Comment


      #3
      I think it's time to seriously get a certified ABYC marine electrician to check out your vessel, he can check out your bonding system and your AC electrical using a half cell.
      If you keep your vessel on a marina all year I cannot figure out how the Zincs are lasting 2 years ??
      Brad & Sharon
      Lady Jake
      1985 4550 EH 700TI /Twin Disc 502
      LaConner,Wa. (summer)
      2003 Scout CC 24' W/225 Yamaha
      kailua Kona,Hi (Winter)

      Comment


        #4
        Originally posted by brad4550 View Post
        I think it's time to seriously get a certified ABYC marine electrician to check out your vessel, he can check out your bonding system and your AC electrical using a half cell.
        If you keep your vessel on a marina all year I cannot figure out how the Zincs are lasting 2 years ??
        That's just it, I had a surveyor come out with a half cell to figure out where I had a leak in current 2 summers ago. I felt a tingle in the middle trim tabs when free diving. We worked out that the forward AC was leaking 1.2 volts when it kicked on. That unit burned out shortly after and I replaced it, and the problem disappeared. He said my bonding system was functioning within normal spec ie. less than 1/2 a volt? That is to say, he could have been wrong then, or something broke recently. Can my system be check out of the water?

        My sailboat zincs would last 2 seasons as well, typically changed between haul outs. We have new panels at the marina.

        Thanks!
        . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

        Comment


          #5
          Bonding wires are green not black so that is a do-it-yourself modification. You can check your bonding system with a multimeter, but if it's beyond your comfort the suggestion of professional help is a good idea. Not solving the problem can be very expensive. A pro can determine if your boat is leaking power or your neighbour is the culprit.
          ​​​​
          1989 26' then 1994 32' now 2001 39'

          Comment


            #6
            Well...

            Isolation transformers would guaranteed solve your problem.

            Why????

            Simply because your ground and neutral are tied together behind the isolation transformer.
            The shore power is separated so there is Zero reason for stray current to travel through the ground conductors to shore power.

            This solves several issues....

            If it’s your neighbors boat isolation transformers solve the problem.

            If you have current using the ground it solves the problem.

            This is not to say that you should allow your boat, if it has a ground-neutral short in a appliance to go unfixed. This is just saying that isolation transformers take a problem like that and remove the damage to your boat component of the problem.

            KEVIN SANDERS
            4788 LISAS WAY - SEWARD ALASKA
            where are we right now​​​​​​???​

            https://share.findmespot.com/shared/...j23OquWOj2N3Xe

            Comment


            • capnken
              capnken commented
              Editing a comment
              visit this site for more on isolation transformers: http://www.charlesindustries.com/main/ma_iso_boost.html
              Seems like a lot of people confuse galvanic and isolation transformers, which are NOT diodes but transformers that truly isolate your boat from dockside electrical issues. I installed a Charles G2 and am glad I did...only issue is cost and weight. Agree with Kevin! Ken

            #7
            And they do go bad. They are just a big diode. Google "testing my isolation transformer" It's an easy test and an easier replacement.
            Tally and Vicki
            "Wickus" Meridian 341
            MMSI 338014939

            Comment


              #8
              Beans, have you taken a good look at your bonding system? The latest ABYC recommendation is to use #8 tinned wire with a green insulation. Strange thing is, it’s the same for a 20’ boat as an aircraft carrier. I’m going to replace mine this spring and my electrician suggested I use several posts rather than sections of wire held with ferals and butt splices. The recommendations specifically call out mechanical connections, so no soldering.
              I’d get your electrician down there to check things out. It could be that someone around you is leaking, but maybe not next to you. Any wood boats that the bilge pump cycles on a lot? Are you using aluminum? If you are in salt water, that’s the recommendation.
              P/C Pete
              Edmonds Yacht Club (Commodore 1993)
              1988 3818 "GLAUBEN”
              Hino EH700 175 Onan MDKD Genset
              MMSI 367770440

              Comment


                #9
                Very sorry to see that. You should consider pulling the prop shafts for inspection. I've never seen sacrificial anodes that still had life left on them mounted to stainless where the stainless corroded so severely.
                Irony
                1989 Bayliner 4588 - EH700TI
                Portsmouth, NH

                Comment


                  #10
                  Originally posted by Kwood View Post
                  I've never seen sacrificial anodes that still had life left on them mounted to stainless where the stainless corroded so severely.
                  Same here. Had you sanded to bare metal under the trim tab zincs?
                  Mike
                  "Allante I" Rayburn 75
                  Previous: '97 4788

                  Comment


                    #11
                    Uncle Bob
                    That is NOT a DIY modification,early Bayliner's used Black wire for the main bonding system. I would bet your old 32 as my 45 and Cool Beans are the same. Remember ABYC are guide lines,they do not have to be followed only CFR's do. That being said I think most manufacturers have adapted ABYC standards and their fore meet all CFR's.
                    Brad & Sharon
                    Lady Jake
                    1985 4550 EH 700TI /Twin Disc 502
                    LaConner,Wa. (summer)
                    2003 Scout CC 24' W/225 Yamaha
                    kailua Kona,Hi (Winter)

                    Comment


                      #12
                      Originally posted by talman View Post
                      And they do go bad. They are just a big diode. Google "testing my isolation transformer" It's an easy test and an easier replacement.
                      You are referring to galvanic isolators, while Kevin was referring to isolation transformers. They are totally different devices.

                      Most, if not all, Bayliner motoryachts came from the factory with galvanic isolators, usually one per shore power inlet. Galvanic isolators are wired in series with the ground (green) wire coming from the shore power inlet. They work by blocking low voltage DC currents, but allowing high voltages to flow freely.

                      Galvanic isolators do fail. Some have a self test light that will indicate a failure, but most do not. As talman indicated, They should be tested. When doing this, make sure the boat is disconnected from shore power, the inverter is turned off, and you test all isolators (if more than one).


                      Isolation transformers isolate the boat completely. The shore power inlet wires are connected to the primary windings in the transformer and induce a voltage in the secondary windings. The secondary windings are connected to the boat's AC system. There's no physical connection between the boat and shore power.

                      Isolation transformers are not prone to failure.

                      1999 3788, Cummins 270 "Freedom"
                      2013 Boston Whaler 130 SS
                      Anacortes, WA

                      Comment


                        #13
                        Guys, very much appreciate all the advice and insight! My bonding system was checked as functional 2 years ago. It isn't the healthiest looking but conducts current. It's also a mix of green and black. Mostly green under the cockpit hatches, black inside, and a mix here and there. Looks easy to redo with all 8 gauge. I have the original galvanic isolator in the lower helm. Part of my winter refit was to pull the shafts and struts to have them checked and rebedded and realign the engines. I want to install the PSS shaft seals.

                        I think I'm going to start with having a pro come out and give my boat a good once over

                        EDIT: One thing that is different, and you guys got me thinking about...my only neighbor has been staying out at his 47 foot cat a lot since summer. And this is the first year he is bow in (as am I). So.....my starboard corner is closest to is boat across the finger pier, which is the trim tab that is the worst. I'm going to leave a note in his cockpit with my number so I can talk to him.
                        . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

                        Comment


                          #14
                          Originally posted by Cool_Beans View Post
                          I think I'm going to start with having a pro come out and give my boat a good once over
                          .
                          Try to find a marine electrician who is familiar with corrosion issues.
                          1999 3788, Cummins 270 "Freedom"
                          2013 Boston Whaler 130 SS
                          Anacortes, WA

                          Comment


                            #15
                            I dunno Brad, my old 32 had green bonding wires, but it was a different decade than yours. Maybe others with 35 year old Bayliners will let us know if they have green or black bonding wires. I'm curious.
                            1989 26' then 1994 32' now 2001 39'

                            Comment

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