galvanised chain plus nylon = rust

[Gunfleet]

Has anyone else noticed their anchor chain splice induces rust to the chain? My anchor chain is good quality but has rusted on the splice but nowhere else. Weird. I also have a good quality Japanese diver's knife which I put a nylon lanyard on. No rust anywhere except where the nylon lanyard touches. What is it?

 

[cindersailor]

I assume that this is due to the fact that nylon absorbs quite a bit of water, your chain/knife is therfore in long term contact with water where it is attached to the nylon providing a good environment for corrosion. Any other ideas?

 

[Remmington]

Friction movement has worn away the galvanising

 

[Gunfleet]

Definitely not friction. Maybe the constant presence of water, but it's quite a powerful effect. I'll try to post a photo when I can.

 

[Guest]

Ditto ... seen it on many a boat surveyed .... I tend to support the replies that water held in the joint is cause ...

Plus being Salt-water .... the salt will likely be precipitated out and remain behind even when dry.

 

[FAITIRA]

No stainless thimble in the splice I hope? or is it rope to chain splice? then it must be moisture as other say.

 

[Allan]

Mine is just the same! I have put it down to moisture and/or salt. I also wondered if there could be anything acidic in the rope from it's manufacture.
Allan

 

[Gunfleet]

No stainless, Bill, unless you count the shackle right at the other end of the chain, attaching the anchor. It's a proper octoplait anchor splice, by the way. I don't really believe the effect is just salt and water. It just seems too strong.

 

[Wunja]

Its caused by the difference in potential between the zinc and the long chain molecules of the nylon.
The solution is to use a Nylon with a lower valency, reversing the potential current, or to install a sacrificial plastic anode.

/forums/images/graemlins/wink.gif

Vince.

 

[GMac]

Rust by the end link is common as muck.

Could be something with the nylon. Is something to do with saltwater though as none of our rodes used in fresh water only do it. Combination of movement, salt and maybe something in the nylon is our best guess.

It is nothing to be afriad of untill it starts getting real intense. Then you had better cut the splice and the link it was around off and start again. Have a close look at the chain link under the splice, it may just spook you. It may not but I've seen more than a few that would.

 

[Thistle]

The sacrificial plastic is most effectively used by handing it to the chandlery staff on entry. It can be recovered before departure on provision of the correct 4-digit code. When used in this way for anodes, the process is sometimes referred to as "anodising".

 

[Topcat47]

Rust is an occupational hazard on a boat. I don't worry too much about my Anchor Chain because it rubs off and my annual examination has never shown significant reduction in chain thickness on any of the links. Iron Oxide is much less dense than steel so the rust always looks worse than it is if it's not been scraped off.

 

[Gunfleet]

Wait till you see the pictures!

 

[bobmay]

Topcat47 has it right, rust is almost 10 times that of steel. Very frightening on first sight.