Hanging Anode, proper Grounding

Don S/V ILLusion · Feb 28, 2019

Corrosion on the “keel bottom”???

LeslieTroyer · Feb 28, 2019

Connect the fish to your bonding system. I’ve seen some where they bond a cleat or stanchion bolt then clip the fish to that.

Bonding systems connect all the underwater metal parts (shaft,metal thruhulls, struts... to a common ground). Or just engine and shaft. Since the corrosion is there that’s where the fish wire should end up

https://www.westmarine.com/WestAdvisor/Marine-Grounding-Systems

thinwater · Feb 28, 2019

If there are actual visible bubbles, that is FAST corrosion. At normal rates, the gas dissolves before you can see it. I'd dig deeper if I were you. It sounds like a wiring problem to me. I would also worry that the keel bolts are involved, which is critical. But not enough info.

Don S/V ILLusion · Feb 28, 2019

QCI said:
The diver says there are rust bubbles are where the keel meets the hull on front side. They look like barnacles but can be rubbed off. Said to install the anode and see if it helps. Never had problem before. Moved to new marina last October. Thanks for info, Les!

If it’s an iron keel, it’s rust, not corrosion. If it’s a lead keel, it won’t corrode from electrolysis very easily. I suspect your diver doesn’t have a clue but was adverse to admitting it.
Regardless, if it is in fact some form of electrolysis, putting a fish on the boat is a bandaid which won’t solve the problem you should be focusing on finding and fixing before it affects other stuff.

Davidasailor26 · Feb 28, 2019

On an iron keel you're talking about oxidation, not dissimilar metal corrosion like we usually think of a zinc preventing. Still I've read things saying a zinc will mitigate that if it's electrically connected to the iron.

Ultimately you'll probably want to grind or sand the affected areas to clean metal and recoat with epoxy to protect it.

PS I assume the "bubbles" are spots where the rust is "bubbling" out as it expands, not actually gas bubbles, correct?

SG · Apr 16, 2019

Why do think a lead keel can't display galvanic corrosion issues?

You have significant pitting from something. My guess is an issue that COULD be your boat, your shore power, or the guy in a slip near you, or the marina.

https://www.jefa.com/install/electro.htm

Tom J · Apr 16, 2019

No offense, but that keel is in tough shape. You might want to think about blasting it to bare metal and resealing with epoxy. I did this on my O'Day 23 with an iron keel. The rehab of the keel worked so well, the keel was still in excellent condition ten years later, in salt water.

SG · Apr 16, 2019

If the keel was "GOOD" and that happened in a short time (as I understand from the posts above) -- then something is going on. ANODE up, make sure it's grounded to the keel (IS YOUR KEEL GROUNDED to the rest of the boat?) and make sure the rest of your metal on the boat is protected. Thru hulls, unless they are plastic.

Then figure-out what's happening. If it's the marina or your marina mates or transients or you or whatever.

Like Tom J said, that's pretty ugly.

You can fix it a bit, but if it's a symptom of bad things, they won't necessarily go away by themselves. The anode can shied you to a GREAT extent (if properly connected).

fstbttms · Apr 16, 2019

The OP's video shows what is clearly rust, not electrolytic or galvanic corrosion. Very, very common on iron keels.

Hanging Anode, proper Grounding

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