Disappearing zinc anode - Beneteau 323

[dLj]

Maine sail - with all due respect - how would the OP have an AC problem on a mooring? He is not using shore power.

Indeed the OP may not know how to see dezincification. But if this is a major electrical issue causing the complete loss of the anode, and it has been doing this for years, there would not be just dezincification, as well you know. But I'm not going to sit here and get into a pissing contest with you.

The OP was asked to provide pictures. I have no idea where the OP is located. One thing that is clear, the OP should likely go find a pro to find out what's going on with their boat. Perhaps I should have said nothing more than that to start.

dj

 

[dlochner]

If the DC leak is intermittent or is only an issue when some device is powered up, then it might be possible to lose the anode with little collateral damage beyond the anode.

Of course the simplest and easiest mistake to make would be using and English system anode on a metric shaft. It would be one those, close but no cigar, embarrassing moments. We've all done stuff like that.

 

[Maine Sail]

Maine sail - with all due respect - how would the OP have an AC problem on a mooring? He is not using shore power.

Indeed the OP may not know how to see dezincification. But if this is a major electrical issue causing the complete loss of the anode, and it has been doing this for years, there would not be just dezincification, as well you know. But I'm not going to sit here and get into a pissing contest with you.

The OP was asked to provide pictures. I have no idea where the OP is located. One thing that is clear, the OP should likely go find a pro to find out what's going on with their boat. Perhaps I should have said nothing more than that to start.

dj

The AC picture/photo was only to point out that I/we/Compass Marine Inc. do this for a living and are heavily trained in both AC and DC corrosion. Just helping to point out that I am not just shooting from the hip on corrosion issues.

The real point was to hire a pro who actually knows this stuff and who can sort it out. If I had a dime for every boat owner, who was a self espoused expert on marine corrosion, and whom insisted their boat was not the issue, and then a corrosion analysis showed it was, I'd probably be retired. (grin)

 

[dLj]

The AC picture/photo was only to point out that I/we/Compass Marine Inc. do this for a living and are heavily trained in both AC and DC corrosion. Just helping to point out that I am not just shooting from the hip on corrosion issues.

The real point was to hire a pro who actually knows this stuff and who can sort it out. If I had a dime for every boat owner, who was a self espoused expert on marine corrosion, and whom insisted their boat was not the issue, and then a corrosion analysis showed it was, I'd probably be retired. (grin)

I, and many others here, know you are not shooting from the hip.

I don't think this OP has espoused that their boat is not the problem here. They were asking for help on determining what the problem may be. It seemed to me they are very open to learning whatever might be causing the problem. Had the OP appeared to not have that type of attitude, I would never have engaged - just as a FYI....

I love your sentence above: "If I had a dime for every boat owner, who was a self espoused expert on marine corrosion, and whom insisted their boat was not the issue, and then a corrosion analysis showed it was, I'd probably be retired. (grin)"

Expand this to "If I had a dime for every Tom, Dick and Harry, who was a self espoused expert on all things metallurgical, and whom insisted their -pick the industry/problem- was not the issue, and then actual professional analysis showed it was, I'd probably be retired." You can times that by 2 for sure... Although I'm not sure I'd need a whole dime...

Your advice to seek professional help is well taken. I don't know where the OP has their boat. So I don't know who to recommend.

dj

 

[Maine Sail]

Your advice to seek professional help is well taken. I don't know where the OP has their boat. So I don't know who to recommend.

dj

Ask around the local yards and see who is the corrosion specialist they call to sort out stubborn problems. Boat yards often bring in outside help for corrosion issues they can't solve..

 

[Sailor Sue]

I’m told not.

Zinc and Aluminum Sacrificial Anodes | Cruising World

Zinc Again: So you think you know the difference between zinc and aluminum sacrificial anodes?

www.cruisingworld.com

My empirical observation has been that zinc anodes glazed over and never changed shape or size. When I switched to aluminum anodes they show a slight bit of deterioration by the end of our 5 month sailing season in fresh water in the Great Lakes.

 

[dLj]

You should use magnesium based anodes for fresh water. Here's an excerpt from West Marine:

 

[dlochner]

With all due respect for the WM advisor, I'll take Steve D'Antonio's advice over theirs. And it may not be as simple the water the boat is in, hull material and whether the boat has galvanic protection is also a factor. The folks over at BoatZincs.Com know corrosion and anodes. I've spoken with them a couple of times about a steel sailing vessel I've worked on. I trust their opinion and products.

https://www.boatzincs.com/pdfs/Chart_A-Which_Anodes_Should_I_Use.pdf

Ask Steve | Steve D'Antonio Marine Consulting

stevedmarineconsulting.com

A few years back I hired a marine corrosion expert to survey the steel sailing vessel having corrosion issues. We spent four or five cold wet hours going through the boat. In those hours I learned a lot about corrosion and even more about how complex corrosion issues can be. If you can't find the corrosion culprit quickly and easily, then it may be time to hire a recognized expert. This expert (who shall remain nameless) drove 6 hours from RI to Syracuse, spent 4 or 5 hours with me, and drove back, then never sent a report. We never sent a check. Go figure.

 

[fstbttms]

We attach a new zinc anode to the shaft of our Beneteau 323 at the beginning of every season. When we pull our boat out in the fall the anode is always gone. We've made sure it's screwed on extremely tightly and last summer coated it with Loctite Thread Locker and it still came off. It's a substantial anode and the boat is only in the water for 3 months so I'm sure it hasn't disintegrated - any suggestions?

Since you have clearly gone the extra mile to make sure the anode doesn't fall off prematurely (and discounting the ridiculous suggestion that someone is stealing it), it seems entirely like that anode actually is depleting within three months. This is borne out by the fact that the anode is always missing after three months. Since you don't seem inclined to have the boat dived or use an underwater camera to check the anode's mid-season condition, I suggest next year you install two shaft anodes. This will (in theory) provide cathodic protection for twice as long as one anode. When you haul at the end of the season, if any of the two anodes remain, you will know that you have a rapid depletion issue from which one anode alone can't protect for three months. You will also know that the cause of the issue is likely to be found somewhere aboard your boat, as is typically the case in these situations.

 

[NYSail]

Yes, but you have ancillary damage in your example. The OP is claiming no other damage other than the missing anode.

i should have been more clear in my original post, saying with no other damages present, it's unusual to have an entire anode gone in only 3 months. I'm referring to small leaks, not huge ones like you are talking about.

If the OPs boat has all plastic thru-hulls, then they won't be affected. This is unknown. But this anode is on the prop shaft. If it's electrical, and happening as fast as stated, there would have to be damage to the prop. Even in your example above, there remains part of that thru hull. In this case, there is nothing left of the anode and no other damage stated.

This has been going on for years. It is not an isolated event. Given what has been stated by the OP, I find it difficult to see how it is electrical in nature.

dj

I have a slip and a mooring. In years past we keep our boat plugged in from Sunday night till Friday morning, then head to the mooring (crowded field) for the weekend. And in years past I would change my zincs once during the season as they would be nearing the end.
However this season, wife and I would again keep boat plugged in at slip Sunday night till Friday morning but instead of the mooring we left the harbor and anchored out...... My prop zincs (1 shaft / 1 prop) lost maybe 50% and my bow thruster zinc lost maybe 25%.

 

[dlochner]

I have a slip and a mooring. In years past we keep our boat plugged in from Sunday night till Friday morning, then head to the mooring (crowded field) for the weekend. And in years past I would change my zincs once during the season as they would be nearing the end.
However this season, wife and I would again keep boat plugged in at slip Sunday night till Friday morning but instead of the mooring we left the harbor and anchored out...... My prop zincs (1 shaft / 1 prop) lost maybe 50% and my bow thruster zinc lost maybe 25%.

Assuming the amount of time at the marina and on the mooring are about the same and nothing electrical was changed on your boat, then something at the marina changed. Could be improved marina wiring or a boat with bad wiring left or moved further away. Count your blessings.

 

[DougM]

Always an interesting discussion...
I am in fresh water, and have periodically been looking for a magnesium shaft zinc that would fit the prop shaft on my 323, which has minimal clearance between the prop and the shaft exit point from the hull. The shaft zinc I have is obviously non functional. That zinc has been on the boat for a decade and looks as good as new. The fasteners themselves also look the same.
As far as I have observed, most of the owners around me have zincs that have never been replaced and probably unaware that magnesium would be the recommended type.

 

[NYSail]

Assuming the amount of time at the marina and on the mooring are about the same and nothing electrical was changed on your boat, then something at the marina changed. Could be improved marina wiring or a boat with bad wiring left or moved further away. Count your blessings.

Or a boat near me on the mooring that has an issue (that 2% Maine Sail mentioned).....

 

[dlochner]

Always an interesting discussion...
I am in fresh water, and have periodically been looking for a magnesium shaft zinc that would fit the prop shaft on my 323, which has minimal clearance between the prop and the shaft exit point from the hull. The shaft zinc I have is obviously non functional. That zinc has been on the boat for a decade and looks as good as new. The fasteners themselves also look the same.
As far as I have observed, most of the owners around me have zincs that have never been replaced and probably unaware that magnesium would be the recommended type.

Try www.Boatzincs.com. They probably have the largest selection of anodes, zinc, aluminum, magnesium anywhere. Decent prices, knowledgeable owner, quick shipping. I've used them for many years and never been disappointed.

 

[Ron20324]

I have not gone back over ALL of the replies, but I have not yet seen any reference to the mooring arrangement as maybe being involved?