Mike, let me offer a clarification and a correction to my
earlier post.

The clarification is to say that the chain will not corrode
UNLESS it is in contact with the anchor. It is quite
possible that at times the links will arrange themselves so
as to avoid making an electrical circuit with the anchor.
But if and when they do, then the very thin galvanizing
layer on the chain will corrode fairly quickly. And as is
often the way of nature's seeming perversity, the links
closest to the bottom (the anchor)and least accessible will
deteriorate first.

The correction is to drop option #1. The idea was to avoid
allowing the chain to contact the anchor, but upon awakening
from what must have been a dream, I see that it makes no
sense at all. The point is that if the chain doesn't contact
the anchor, however you achieve this, you won't see corrosion.

I've only been talking about galvanic corrosion. Both the
chain and the anchor will self-corrode even if they are made
of the same material.

Chuck


chuck wrote:
Hello Mike,

Yes, the galvanized coating on the chain will be sacrificed to protect
the stainless anchor. It is generally not recommended that you use
galvanized chain with a stainless steel anchor. Used continuously as a
mooring would be particularly bad.

If you must, here are three things you can do:

1. Use nylon rode for the first 50 feet from the anchor. At that
distance, the stainless will not corrode enough zinc to notice. You
could probably skip the next two steps if you did this.

2. Attach a sacrificial zinc directly to the anchor, making good
electrical contact. Easier said than done, perhaps. The problem with
this is that it will need to be replaced maybe once per year. Worse, you
may have to pull it up more frequently at first to verify that the zinc
is working and your chain is surviving. It would also be good to devise
a system to prevent the chain from touching the anchor. You want the
zinc anode to be closer to every part of the anchor than the chain is.

3. After attaching a sacrificial zinc to the anchor, paint the anchor
with an epoxy paint intended for such use. There are some epoxies
designed for painting props that would work. Be careful not to paint the
zinc anode! Buried in seabed muck, the anchor might have a long a
productive life.

Of course, you could use stainless chain. It might be cheaper.

Good luck!

Chuck













wrote:

Hi,

I just found a 90 pound stainless steel plow to use as a mooring
anchor. The guy I got it from said that he thinks there is an
electrolysis issue if you use galvanized chain. He said that there was
something I needed to do, but couldn't remember what.

Anyone have any clues for me?

Thanks,

Mike.
Beaufort, NC