Total lower unit ruined by electrolysis have not looked at engine yet. Zincs were properly inslalled. Any one with similar problems? Thoughts as to cause?
[Posted by: Robert Page
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Electrolysis
Moderator: forumadmin
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Guest
Robert,
Obviously you're getting stray currents from somewhere. I'd suspect leakage from shore power, from a neighbor's genset, from chafed insulation on a wire, in that order.
We've taken the additional precaution of hanging a Grouper zinc off a stern cleat, and clipping it to the stern pulpit when not sailing.
[Posted by: Dan Grossman
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Obviously you're getting stray currents from somewhere. I'd suspect leakage from shore power, from a neighbor's genset, from chafed insulation on a wire, in that order.
We've taken the additional precaution of hanging a Grouper zinc off a stern cleat, and clipping it to the stern pulpit when not sailing.
[Posted by: Dan Grossman
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I have had to replace my prop due to electrolysis. The Flexo Fold prop is electrically isolated from the saildrive leg so the zinc does not protect the blades. In five weeks the new prop is already showing serious pitting. I had my diver attach a fish zinc to the prop blade by an allegator clip but the surging conditions broke it loose. I am at a loss of what to do. We measured over 900 mv and about 200 mamps in the water so there is stray current coming from somewhere.
Sounds scary, makes me want to double check my system and check for stray current. I'm going to call the divers tomorrow and have them check the zinc and prop tomorrow.
BTW- has anyone found any documentation for the ProMariner galvanic isolator? Particularly, what does the Bonding Over/Under sensor measure? I assume it's letting me know the bonding connections are working. The other sensors are ok. I can't find any documentation on the bonding system sensors and haven't gotten a good explanation from the local electronics guru. It was showing normal when at another marina before I bought my boat this fall, but since I've moved it to my marina (an older one undergoing a major upgrade and higher risk for stray current), my sensor always shows the Bonding as "under"
BTW- has anyone found any documentation for the ProMariner galvanic isolator? Particularly, what does the Bonding Over/Under sensor measure? I assume it's letting me know the bonding connections are working. The other sensors are ok. I can't find any documentation on the bonding system sensors and haven't gotten a good explanation from the local electronics guru. It was showing normal when at another marina before I bought my boat this fall, but since I've moved it to my marina (an older one undergoing a major upgrade and higher risk for stray current), my sensor always shows the Bonding as "under"
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Guest
re: Electrolysis
all. Just signed up for class association membership as I am planning on purchasing a J109 in the near future. In regards to the electrolysis issue: 3 factors have to be present for electrolysis to be present; dissimilar metals, an electrolyte (ie: saltwater), and a connection between the two metals besides the electrolyte. This galvanic corrosion can cause currents measured in milliamps. What can also occur is stray currents that are caused by shorted electrical circuits either AC or DC. The DC currents are more devastating. I would have to have a electrical diagram of the 109 in question to determine any probable electrical paths, but suggest you start with assessing whether a galvanic isolator is installed and working properly. When a 110 line is connected to dockside power every boat in the marina is potentially connected together through the ground connection. An isolator allows AC current to pass but blocks small amounts of DC. A galvanic isolator can be tested with a multimeter to make sure it is working properly. For those interested I suggest purchasing a copy of Nigel Calders' excellent book "Boatowners Mechanical and Electrical Manual" which discusses isolators in detail and the latest design standards they should meet. In addition make sure that all AC circuits are being protected by the isolator, ie: is there a TV cable or telephone cable on the boat that bypasses the isolator? Try to reduce the amount of time that the 110 line is connected. On the DC side look for any wiring that has connections in or near the bilge that could be leaking stray current into the bilge water, be especially attentive to any pumps and/or pump connections in the water. Hope this helps.
[Posted by: Brad Rieger]
[Posted by: Brad Rieger]
Culprit is Xantrex Link 20 Battery Monitor.
Hull 244 is in brackish water at a slip in Solomons, MD. On arrival, hung zinc groupers over the side attached to chain plates. Experienced massive zinc oxide formation on groupers over 2 week period. Boat has shore power option with galvanic isolator (all three lights are green when energized) and 3x105 amp-hour AGM (Sealed Lead Acid) batteries. Shore power is not connected. Removed fuses from Link 20 and installed new zinc groupers. No futher zinc oxide formation noted in last six months. Shore power connected or not is no problem. Charging batteries with a extension cord and batter tender is no problem. Link 20 is probably leaking current to ground bus from connection at the battery shunt. Not sure if it is a good idea to remove the shunt to ground bus connection.
Hull 244 is in brackish water at a slip in Solomons, MD. On arrival, hung zinc groupers over the side attached to chain plates. Experienced massive zinc oxide formation on groupers over 2 week period. Boat has shore power option with galvanic isolator (all three lights are green when energized) and 3x105 amp-hour AGM (Sealed Lead Acid) batteries. Shore power is not connected. Removed fuses from Link 20 and installed new zinc groupers. No futher zinc oxide formation noted in last six months. Shore power connected or not is no problem. Charging batteries with a extension cord and batter tender is no problem. Link 20 is probably leaking current to ground bus from connection at the battery shunt. Not sure if it is a good idea to remove the shunt to ground bus connection.