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View Poll Results: Bond or not to Bond
Save the case of rum till after you bond it. 1 33.33%
Screw it, replace the zincs, and drink the rum now. 2 66.67%
Voters: 3. You may not vote on this poll

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Old 25-09-2021, 12:07   #1
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The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

Hey everyone! Beneteau 50

I just hauled out 6 months after the last haul (before we purchased the boat)

In the last month or so while going through electrical and rewiring the ac and dc systems, it became apparent the electrical was a total mess. With new buss bars, blue sea panels, phoenix inverter and tons of wiring cleanup, it became apparent the boat is not bonded and there is no grounding system on the boat.

On the survey there was small evidence of electrolysis on the prop. So when redoing the 110v system, I have been contemplating bonding and grounding the whole boat. With 21 through hulls its going to be pretty stupid.

When I hauled out this time, there are three zincs. one on the prop, one on the shaft, and a sandwich sand dollar sized disc on the back of the keel. They looked like alka seltzers. Creamy. I brushed off all the soft material and there is about 40% left of them since April. Yikes! Also the prop has quite a bit of pink spotting.

Thoughts???

My thought is to install through bolts with a big zinc, and rund 6 awg down one side of the hull. Run a couple buss bars and link all keel bolts, mast, and through hulls.

Big job. Just dont know how the boat lasted 20 years with hardly any protection. Then in a couple months Im showing enough corrosion to eat everything up in super fast. I have been anchored off a private island with large docks and massive private structured and there is likely a underwater cable nearby, also a crowded anchorage.

What would you do? What are your thoughts? Leave it isolated? Bond it all?
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Old 25-09-2021, 12:35   #2
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

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Originally Posted by JArcherM View Post
.

What would you do? What are your thoughts? Leave it isolated? Bond it all?
Get someone who actually knows what they are doing involved
Hard to find in these days where "everyone's an expert"
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Old 25-09-2021, 12:47   #3
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

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Originally Posted by Simi 60 View Post
Get someone who actually knows what they are doing involved
Hard to find in these days where "everyone's an expert"
Thank you, yes exactly. Everyone has a different answer. Obviously many boats are manufactures isolated so there must be a reason. What I am finding is that its an ongoing debate. I have talked to a few folks who have quite a lot of experience, electricians etc... but I get conflicting answers. I personally have no problem doing the work, just before taking on this job, some outside experience from folks who have seen the benefits or lack there of after bonding or vice versa. Amazing to me that a boat like Bene would not be bonded or have any through bolts for zincs.

Based on what I am seeing... electrolysis is happening, and whether its from onshore causes, other boats or my own it needs to be stopped. So as it sits I am leaning to running everything to several large zincs.
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Old 25-09-2021, 15:36   #4
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

In the beginning, bonding was seen as a way to bring a bunch of dissimilar metals to the same potential, and then sacrificial zincs could "take the hit", so to speak, to protect the underwater fittings.
Today, the primary use of bonding is not to protect the boat, but to protect people from electrocution hazards due to AC power on board, by allowing a low resistance path to ground in case some AC unit had currant leakage from whatever cause.
That's why ABYC wants to see the AC ground, (green wire,) connected to not only the bonding system, but also the ships DC ground buss.
It's not, (by a long shot,) a perfect set up, (you can end up with a "pea soup" of various impressed voltages from that arrangement,) but it can work to protect people.
As for the prop, it's might not the highest on the totem pole,, a passivated stainless shaft, and bronze sea cocks can be higher, (props are generally Manganese Bronze,) and as such have a high zinc content.
Your observations are consistent with having some currant leakage, (wether AC or DC,) into the water, usually by way of the engine.
Why so many boats use the engine as a "Grand Central Station" for all the various grounds is a topic for another thread,
If their is some currant leakage that is causing the prop to discolor/spot, bonding the boat won't change that,, it will only spread the leakage amongst more underwater fittings.
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Old 25-09-2021, 21:31   #5
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

I assume your 6 months of the zincs being 60% eaten was primarily at a dock with AC plugged in?? If so, it is probably not a great test to determine if you have an onboard problem. In addition, even if you had an onboard problem it may have gone away with the major rewiring you did.
You might want to see how things go with the new setup and being primarily at anchor before investing in another major project.
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Old 26-09-2021, 09:47   #6
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

Make sure your anodes are of the correct material: Magnesium for Fresh; Zinc for Brackish/salt; Aluminum for salt.

If your thru-hulls are not metallic, they can not be bonded. Most boats I've seen have Marlon thru-hulls and seacocks.
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Old 26-09-2021, 10:35   #7
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

There is no such thing as electrolysis on a boat. There is galvanic corrosion. So let me understand the choices you pose.

1. Don't bond everything together. So, maybe you are implying that you might bond some metals but not others. So, you just let the others fend for them selves?

2. You bond everything to one common point and install the correct anode of the correct size and protect everything?

Let me think about this. Hmm I think I have an answer.
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Old 26-09-2021, 10:38   #8
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

My Bene 473 used to live in a marina, and I was constantly replacing zincs until I installed a galvanic isolator.

I also replaced all of my thru-hulls and ball valves, along with all the associated fittings, with marelon.

I have an expensive (to me) flex-o-fold prop, so I check the zincs every month, but with the galvanic isolator they last nearly a year.
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Old 26-09-2021, 10:44   #9
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

I completely forgot about the galvanic isolator. I have a friend that has a Beeny 423 and he was going through anodes every month. I noticed the boat didn't have any galvanic isolators. I suggested he put them on. His monthly anode replacement problem went away. But, just remember if there is a large amount of stray galvanic current, a galvanic isolator may not save your metals.
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Old 26-09-2021, 11:04   #10
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

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Originally Posted by JArcherM View Post

On the survey there was small evidence of electrolysis on the prop. So when redoing the 110v system, I have been contemplating bonding and grounding the whole boat. With 21 through hulls its going to be pretty stupid.
First thing is never take electrical advice from someone using the word "electrolysis". That is uniformed dock talk using a catchy word.
"electrolysis" does not occur on boats. No one trained in Marine corrosion will use that word.

You are dealing with either stray current or galvanic corrosion issues.

Consult an ABYC tech certified in marine corrosion.
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Old 26-09-2021, 12:53   #11
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

Before you settle the bonding questiion, check the metallurgy of your thruhulls and seacocks. In my 1998 Beneteau 50, these were all brass, not bronze. Brass has zinc as part of the alloy. In seawater, the zinc will migrate out of the brass (galvanic action), leaving weak crumbling copper metal behind. After 4 thruhull failures and 1 seacock failure, I have replaced all of mine with GRP, which does not need to be bonded. Yes, it's expensive, but probably physically easier than running bonding wire. Just grind off the external flange and pop the thruhull and seacock back into the boat, disconnect the hose, and rebuild. The GRP valves are much bigger than the old brass ones, so some rearrangement will probably be necessary. Two other Beneteau owners I know have had the same problem. The rumor I heard was that bronze was hard to get in europe at one time, which is why Beneteau went with brass. Brass will probably last 15-20 years, depending on galvanic conditions, but gets risky beyound that. Go with GRP, you'll sleep better at night.
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Old 26-09-2021, 13:22   #12
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

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Originally Posted by Steve OBrien View Post
Before you settle the bonding questiion, check the metallurgy of your thruhulls and seacocks. In my 1998 Beneteau 50, these were all brass, not bronze. Brass has zinc as part of the alloy. In seawater, the zinc will migrate out of the brass (galvanic action), leaving weak crumbling copper metal behind. After 4 thruhull failures and 1 seacock failure, I have replaced all of mine with GRP, which does not need to be bonded. Yes, it's expensive, but probably physically easier than running bonding wire. Just grind off the external flange and pop the thruhull and seacock back into the boat, disconnect the hose, and rebuild. The GRP valves are much bigger than the old brass ones, so some rearrangement will probably be necessary. Two other Beneteau owners I know have had the same problem. The rumor I heard was that bronze was hard to get in europe at one time, which is why Beneteau went with brass. Brass will probably last 15-20 years, depending on galvanic conditions, but gets risky beyound that. Go with GRP, you'll sleep better at night.
This is a well known issue. I've seen these brass valves crumble in 5 years.

http://www.pcmarinesurveys.com/Paul%...20Seacocks.pdf

http://www.pcmarinesurveys.com/Paul%...0Mongering.pdf
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Old 26-09-2021, 14:10   #13
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

Always willing to be educated/corrected but my understanding is that "electrolysis" is due to "stray current" i.e the kind of thing you get plugged into a dock AC
Galvanic corrosion is due to dissimilar metals and the presence of an electrolyte, in this Sea Water. Yes, they are quite different but electrolysis does exist. To be clear, the correct term is electrolytic corrosion NOT electrolysis.
The MAIN difference is in electrolysis you have an outside electric current introduced into the mix.

I have a Steel boat and have ( as all metal boats should) an Isolation transformer to prevent electrolytic corrosion.
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Old 26-09-2021, 14:24   #14
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

I had a similar issue for 2 seasons. I was going through zincs in months, lost a lot of lead from the keel and some pink on the prop. I added a galvanic isolator after the first season and I also moved from the dock (I kinda thought it was stray current from the dock) to a mooring. That did not fix the issue... I also tried isolating which circuit was the problem using a calibrated cell (i forget what it is called), and lifting bonds, but i got inconclusive results.


The solution, I Lifted off the bonding from the engine block to the keel. I removed as much of the old abandon wires the PO left behind when they repowered or replaced an electronic component. I did find some live wiring they left laying in the bilge. I also added Pos & negative terminal strips and cleaned up the wires around the battery. Which of these was the smoking gun, I do not know. But that was the end of the galvanic corrosion issue. I also had to strip the keel, interlux 2000 barrier coat it, fair and paint it... twice
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Old 26-09-2021, 14:28   #15
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Re: The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

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Always willing to be educated/corrected but my understanding is that "electrolysis" is due to "stray current"
No ! Stray current is stray current. Electrolysis is a different process. Electrolysis is the forced introduction of a current in an electrolyte to separate the components. In water this produces hydrogen and oxygen or it could refer to hair removal at a ladies salon .

Seems like semantics to some folk but not those educated in the issue. Again ... hire someone who knows this stuff.
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