Anode disappear after 1 year

[lawrence_craig]

Hi there.

I have a Bav46 2007 with an anode on the sail drive and an anode connected to the engine. Both were new in June 21. T

Before wintering the boat in Oct, both anodes were ok with some standard pitting (about 80% remaining). We left the marina today and when I checked under the boat, the hill/engine anode was all but gone. The sail drive anode is fine.

I take it this was caused potentially by stray electrical current in the marina. Is there anything that might be an issue on my boat that I can check? With the anode gone (I don’t know how long it has been gone), what would the implications be? This also seems very quick for an anode to go!

Thanks!

[Calif.Ted]

Diver replaces zincs on my direct drive propshaft and strut about once a year, if they need replacing more often he lets me know and then me and the dockmaster go looking for stray currents.

[Shrew]

Some marinas are hot. I had a 28 foot express that Id get 40% zinc loss every 3-4 months. Keep an eye on the rate of deterioration and establish a change schedule accordingly.,

[argold57]

You can take a clamping ammeter and put it on every shore-power cable in the marina. It should read close to 0. Find one with some 10's of milliamps on it and you can ask the marina manager to contact the owner.

The clamping meter will not interfere with the power flow to any boat.

[argold57]

Is there a steel breakwater at the marina? If so, ask the marina manager about the galvanic protection system on it.

[fstbttms]

Rapid anode depletion is almost always caused by an issue aboard the boat in question. Look there first.

BTW- in my experience, the "hot marina" is largely a wives tale.

[boatpoker]

Originally Posted by fstbttms

Rapid anode depletion is almost always caused by an issue aboard the boat in question. Look there first.

BTW- in my experience, the "hot marina" is largely a wives tale.

As a retired Certified Marine Corrosion tech ... I completely agree.
I've done hiundreds of corrosion surveys and have yet to see a "hot" marina.

PS. Anodes disappearing in a year is not execessive depending on the waters.

[argold57]

Originally Posted by fstbttms

Rapid anode depletion is almost always caused by an issue aboard the boat in question. Look there first.

BTW- in my experience, the "hot marina" is largely a wives tale.

I have two stories that prove that hot marinas exist:

1: The Navy Admiral's "barge" at Elliott Bay Marina in Seattle, close to a steel breakwater that had a defective galvanic suppression system. The Marina ended up paying for repairs to the barge. (The admiral's son was in the scout troop I was an asst' scoutmaster for and he used to go camping with us so I heard it directly from him.)

2) My own boat, lead keel was getting "burned". Perfectly cylindirical, silver dollar sized spots of corrosion on the keel. Two slips over we found a boat with 230 milliamps of stray current and the transformer was the other side of my boat. The stray current went through my bonded keel back to the transformer.

These issues are very real.

[fstbttms]

Originally Posted by argold57

The Navy Admiral's "barge" at Elliott Bay Marina in Seattle, close to a steel breakwater that had a defective galvanic suppression system. The Marina ended up paying for repairs to the barge.

Did anybody else have an issue? Did the marina have to pay for anybody else's repairs? No? Not a hot marina then.

Originally Posted by argold57

My own boat, lead keel was getting "burned". Perfectly cylindirical, silver dollar sized spots of corrosion on the keel. Two slips over we found a boat with 230 milliamps of stray current and the transformer was the other side of my boat. The stray current went through my bonded keel back to the transformer.

A neighboring boat with electrical issues that you are sharing does not constitute a "hot marina." It constitutes a neighboring boat with electrical issues that you are sharing.

[lawrence_craig]

Thanks for the info guys, very helpful.

As I am unsure of how long the anode hasn't been functioning for, what are the possible implications of not having an anode? Should I be looking along the waterline elsewhere on the boat for corrosion?

[Jackoski]

I beleive the stray current normally goes through the earth of the shore power have you got galvanic isolator installed? Needless to say no anode means something else is being eaten away.

[CDR Smith]

+1 to what Jackoski said. Cheap insurance.

[pcmm]

To me its also and interesting detail that the Hull anode is depleted but the Saildrive one is not...

[malbert73]

Get one of these, read the manual and follow the directions. And install a galvanic isolator

https://www.boatzincs.com/corrosion-...ode-specs.html

[argold57]

Originally Posted by lawrence_craig

As I am unsure of how long the anode hasn't been functioning for, what are the possible implications of not having an anode? Should I be looking along the waterline elsewhere on the boat for corrosion?

Look closely at your keel. As I said, stray currents can "burn" them

The implication of not having a sacrificial anode is that whatever it should be protecting will corrode (sometimes pretty quickly!)

Originally Posted by pcmm

To me its also and interesting detail that the Hull anode is depleted but the Saildrive one is not...

Saildrive may be made of aluminum and bonded differently from the hull zinc. (Aside, do not use copper paint on aluminum!)