Installing a zinc anode on the anchor

[Korvessa]

Hi Cruisers,

Has anyone ever done, or seriously considered putting a sacrificial anode on their anchor? I was thinking an aluminum anode would be ideal as it would be preferred food for the galvanic monsters of the deep.

In theory, this should protect the galvanizing of the anchor and chain. I would drill a small hole in the shank of the anchor and through bolt it. What do you think?

Korvessa

[Snowpetrel]

I've often thought about it. I know they use anodes on the steel craypots around here, though they are bare steel.

It would be interesting to see if an alloy anode say 1 meter away from a zinc coated part will protect it, of the the nearer zinc will waste first?

[GTom]

I was thinking how to de-rust my anchor - this could be an option

[gjordan]

I would not drill a hole in the shank. Even a small one might make it weaker. I think a zink is a great idea, but mounting it without compromising the anchor strength (holes) would be critical. Lets see what people come up with? Grant.

[OrinocoFlo]

That’s what the galvanized coating is for. Galvanized = zinc.

[GTom]

Originally Posted by OrinocoFlo

That’s what the galvanized coating is for. Galvanized = zinc.

Mine doesn't have a drop of the coating left. Regalvanization would cost the same as a new anchor.

[Korvessa]

Originally Posted by gjordan

I would not drill a hole in the shank. Even a small one might make it weaker. I think a zink is a great idea, but mounting it without compromising the anchor strength (holes) would be critical. Lets see what people come up with? Grant.

My anchor has a hole in the shank, through which the anchor shackle goes. I'm not too worried about it.

I would want to put it high up on the shank close to the shackle though in order not to inhibit the ability of the anchor to bury deeply.

[briblack]

An interesting idea. One of my friends suggests that his chain has lost most of its galvanizing because of electrical leakage going down it. Given the electrical installed in the wet environment of the chain locker, this seems very possible. At least making sure the anchor windlass is tied in well to the boat's grounding circuit seems like a good idea.

[fatherchronica]

There was a thread a month or so ago about an anchorage on the west coast of Mexico where peoples ground tackle failed due to intense corrosion, possibly stray current from a downed UFO according to the History Channel possibly. I suggest asking an authority, or this guy. But, I think it is a good idea and I am going to add anodes to my primary and secondary anchors at least. Pretty cheap insurance, and anodes you can easily check all the time.

[SouthernPride]

Can't you re-galvanize the anchor by spraying a zinc coating on it. Lowes and home depot sell the exact same Zinc spray that you pay 4 times the price for from a marine supplier.

[sailorchic34]

Attaching a zinc anode to an anchor or anchor chain would protect the steel chain and anchor. The only issue is if there is poor electrical contact for what ever reason between chain links and the anode. I would use zinc and not aluminum as the zinc anode would protect the zinc galvanizing better, generally speaking.

[Korvessa]

Originally Posted by briblack

An interesting idea. One of my friends suggests that his chain has lost most of its galvanizing because of electrical leakage going down it. Given the electrical installed in the wet environment of the chain locker, this seems very possible. At least making sure the anchor windlass is tied in well to the boat's grounding circuit seems like a good idea.

My chain was destroyed by 2 stainless steel hose clamps that are in the bottom of the chain locker, securing a propane vent. The wet chain sat for (years probably) in contact with the stainless hose clamps and is rusted beyond redemption in some areas.

[boat driver]

interesting indicator of a galvonic issue, but maybe get a bolt type xinc or a shaft zinc (clean a used one) and bolt it firmly into chain as far up as possible without interfering with windlass.

Avoiding a sidebar discussion about electrolysis/galvanic corrosion, the anchor will not eat up in the mud unless serious current is present- and I suspect that other indicators will precede. But slower issues are going to develop in the chain within a couple links of the anchor and more exposure to the salt water (above mud line) . Picture a battery post and the fuse- the chain is essentially the wire and the zinc would be the fuse.
If you note quick degrading of the zinc in a short period- then personally I would investigate environmental location and windlass. If degrades over a month by month check, then it is doing its job and protecting the chain.

Vessels that sit in the mud at low tide often experience lower zincs degrading faster than upper zincs.


This would be an interesting experiment- please report back your results.

[Dave22q]

I would not drill the anchor. If I wanted to attach a zinc anode I would wire it using 50# monel or heavier.

[Pauls]

Attaching a zinc anode to a galvanized anchor won't help protect the galvanizing much because both are the same metal. But if you attached a chunk of magnesium, which is significantly lower on the scale than zinc, that would protect the galvanizing. I think its a good idea.

For an anchor that has lost its galvanizing then attaching a zinc is an excellent idea. Make sure that your attachment method has very good electrical conductivity or it will be ineffective. By far the best way to attach zincs to a steel part is to use a zinc made for steel boats with a cast in steel bar. Bolt the bar on, but also make a small tack weld from the bar to the anchor. This guarantees a perfect electrical connection which will not degrade over time.