Electrolysis and copper bottom paint

[sailingchiro]

I recommend you disconnect all your green wires off the buss bar and check resistance to the white wires on your AC side. Find the green wires that have low resistance to white wires or rather grounded to white wires. Those will be your most likely candidates.
On our boat it was the inverter charger and genset. The genset is supposed to be bonded white to green but can't be connected while using shore power. The inverter charger bonds green to white if no shore power is present.
When the inverter charger senses shore power, it opens the connection. Mine wasn't opening fast enough and shutting down the marina's new GFI circuitry.
My genset has a 3 pole switch that disconnects from the AC panel when not in use. The inverter charger I put on the same 3 pole switch to disconnect it from the panel when not in use. I have not eaten a zinc since in a year.
Had the leakage checked, no leakage present. my neighbor on the other hand. Just sayin.

[InTheDish]

Following

[deltasig]

+1 for Zimar.

I use them since 2001 and I have to admit that I am not a good customer; they last for a long time. So, although initial purchase is a bit more expensive, I save by replacing every three years (21 months in water).

[DD788Snipe]

Following.

[bobatkins]

This thread caught my attention because of the mention of copper bottom paint.

I have a 2005 Hunter 41 and over the years I noticed that whenever I had a fresh bottom paint job (70% copper, hard paint not ablative) I would start burning prop and shaft zincs up every 1-2 months or about three times as fast as before the bottom paint job was done. Yes, my boat has a galvanic isolator and I had tests done to determine if there was any stray current leakage from my boat or in the surrounding water. Nothing was found.

I lived with this until the 3rd bottom paint job when I finally figured out what was going on. I have a solid lead fin keel that had areas where the primer was missing and/or in poor condition. The keel is bonded and when coated with nice fresh conductive copper paint it created a good battery that burned up the zincs much faster than 'normal'. I even switched to aluminum zincs which slowed the burn rate down but at one every 2-3 months that was still too fast. The problem would resolve after about 12-16 months when most of the copper paint on the un-primered areas of the keel would burn off and the zinc burn rate would be close to 4-5 months which I consider acceptable.

In an effort to fix the problem, I had the keel completely stripped and re-primed with 3 coats of epoxy primer and then bottom paint. The zinc burning problem improved afterwards however, it took more than one attempt to get a decent but not perfect primer bond to the keel. The first time around, there were several large areas on the keel that had bottom paint separation which I assume was due to either poor primer bond with the bottom paint and/or poor primer bond with the keel that allowed conductivity through to the paint which in turn lifted the bottom paint.

After the 2nd strip and re-prime of the keel using heat lamps to ensure a good primer bond with the keel the issue was substantially improved however, on a subsequent diver inspection, there were still several areas of 25-50 cent sized blisters (only on the keel) where the bottom paint had lifted. It would seem that getting a perfect primer bond with the entire surface of the keel is quite difficult.

I'm fairly certain that if the keel bonding were removed that the problem would be completely solved but I don't feel comfortable doing that.

[Davo1404]

Originally Posted by bobatkins

This thread caught my attention because of the mention of copper bottom paint.

I have a 2005 Hunter 41 and over the years I noticed that whenever I had a fresh bottom paint job (70% copper, hard paint not ablative) I would start burning prop and shaft zincs up every 1-2 months or about three times as fast as before the bottom paint job was done. Yes, my boat has a galvanic isolator and I had tests done to determine if there was any stray current leakage from my boat or in the surrounding water. Nothing was found.

I lived with this until the 3rd bottom paint job when I finally figured out what was going on. I have a solid lead fin keel that had areas where the primer was missing and/or in poor condition. The keel is bonded and when coated with nice fresh conductive copper paint it created a good battery that burned up the zincs much faster than 'normal'. I even switched to aluminum zincs which slowed the burn rate down but at one every 2-3 months that was still too fast. The problem would resolve after about 12-16 months when most of the copper paint on the un-primered areas of the keel would burn off and the zinc burn rate would be close to 4-5 months which I consider acceptable.

In an effort to fix the problem, I had the keel completely stripped and re-primed with 3 coats of epoxy primer and then bottom paint. The zinc burning problem improved afterwards however, it took more than one attempt to get a decent but not perfect primer bond to the keel. The first time around, there were several large areas on the keel that had bottom paint separation which I assume was due to either poor primer bond with the bottom paint and/or poor primer bond with the keel that allowed conductivity through to the paint which in turn lifted the bottom paint.

After the 2nd strip and re-prime of the keel using heat lamps to ensure a good primer bond with the keel the issue was substantially improved however, on a subsequent diver inspection, there were still several areas of 25-50 cent sized blisters (only on the keel) where the bottom paint had lifted. It would seem that getting a perfect primer bond with the entire surface of the keel is quite difficult.

I'm fairly certain that if the keel bonding were removed that the problem would be completely solved but I don't feel comfortable doing that.

I have a lead keel bolted to a timber hull. Yacht built in 1972. It has never had keel bonding. The only time that I have had trouble with paint adhesion to the lead was when I installed an HF radio & used a keel bolt as part of the counterpoise. Finally clicked on to what was causing the problem. Removed the cable & repainted the lead with an epoxy system, no problems in the last 8 years.

[bobatkins]

Originally Posted by Davo1404

I have a lead keel bolted to a timber hull. Yacht built in 1972. It has never had keel bonding. The only time that I have had trouble with paint adhesion to the lead was when I installed an HF radio & used a keel bolt as part of the counterpoise. Finally clicked on to what was causing the problem. Removed the cable & repainted the lead with an epoxy system, no problems in the last 8 years.

The risk with not bonding a keel is that a lightning strike could sink the boat by blowing a random hole(s) through the hull.