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Sail & Rigging - Corrosion on our new standing rigging
04 December 2013 - 05:11
Join Date: 10 April 2010
Posts: 32

Corrosion on our new standing rigging

Dear Fellow Swan Owners,

Six months ago we replaced our standing rigging, which we think was original (from 1979). Already, thereappears to be significant signs of corrosion where the wire joins the eye fittings at the deck, as well as corrosion spiraling up the wire on the diagonalwires between the first and second spreaders (see the photos below). The wire is 5/16" 1x19 type 316. The prior rigging (30+ years old) had no such corrosion. The prior rigging had some sort of sealant where the eye and wire joined; the boatyard did not use sealant at the joint in the new rig.In response to our concerns, the boatyard sent us rust cleaner and said not to worry. We're not so sure.Should sealant at the joint have been used? Is the eye fitting inferior stainless steel? What would be a good remedy? Any comments/suggestions about this situation would be most welcome.

Mark (Anthea, Swan 41)

05 December 2013 - 05:04
Join Date: 06 September 2013
Posts: 53

Lars should probably weigh in, but this does not look normal to me. Wrong alloy for standing rigging?

Don F/411 Zoe

05 December 2013 - 11:55
Join Date: 02 January 2008
Posts: 1547

Dear Mark
The problem appears to be local near the terminals, and caused by contamination of some sort. Suggest you try the rust cleaner, if the rust comes back the cleaner is not a remedy. For example using tools of ordinary steel on stainless leaves traces of the rusting steel on the contact surfaces, these can be removed with a cleaner, but here the wire strand surfaces are affected.
Is the rust streak on the terminal upper end flowing down from the strands above, or is the terminal rusting locally? Is there dust/sand on the upper end surface of the terminal?
Has the boatyard used grit inside the terminal to improve the grip?
Originally there were Norseman swageless terminals and a sealant was used as you observed. There are differing opinions about the use of sealants, some claim that this allows the wire to slip out of the terminal at low loads, and that it causes increased corrosion inside.
In order to hold the wire securely the swaging must be done correctly, i.e. the diameter reduced a prescribed amount, and the manufacturers of the swage fittings have tables specifying the diameter before and after swaging. Suggest the diameters are checked, there are some letters probably stating the fitting manufacturer partly visible at the bottom of the second picture you posted.
Sealants use different curing systems, and some of them produce acids, this is usually felt as vinegar smell and not desirable in this application.
Kind regards

06 December 2013 - 01:37
Join Date: 25 July 2012
Posts: 30

Hi Mark,

Yes it does look bad for such a new rig.
Firstly the question of sealant in the terminals: there are 2 schools of thought, those who use it in swaged terminals and those who do not and they both think they are correct!   So I do not think that is an issue here.
Next, the stain spiraling up the wire: probably you have a contaminant higher up and in fact the stain is coming down, making the bottom terminal look like the 'bad guy'. I am not saying there is no problem with the bottom terminal, it just looks worse than it is and you have a problem higher up (possibly as well).

Is the staining on all 1X19 wires or only some?  If only some it may not be the wire or terminals at all.

Contamination can be caused by non-316 washers or pins - Clevis or cotter. 

When the wire was cut did the rigger use a cutting disk? This can leave contaminants which in time, like 6 months, can create havoc. 

Etc. etc. 


Have a look around to see what might be the cause. Sometimes it is evident and easily remedied (by your rigger!).  It will mean you, or someone, going aloft, but it might be time well spent. 


Good luck

David 43/12


06 December 2013 - 04:54
Join Date: 10 April 2010
Posts: 32

Dear Lars and David,

Thank you both very much for your thoughtful and insightful comments.  We will seek to determine if the corrosion is from the terminal or from some sort of contamination in the local area, or both.  The suggestion to clean the rust and wait to see if it returns is a good one.  We will also get answers to the other questions Lars asked, e.g. was grit used in the swage for grip and what the post-swage terminal diameter is.  It is also good to know that there is not a consensus about using sealant.  It seems to me like the rust is of local origin, and not streaming down from something higher up - though this will be thoroughly checked out.

We know have a solid base of information with which to approach the rigger.  And the fact that the rust on the starboard lower terminals is less than on the port terminals also seems to be a good sign (pictures attached below).

We remind ourselves that while there are some issues with the new standing rigging, replacing it enabled us to arrest the galvanic corrosion on the mast and hopefully secure another 30 good years of life for it and all the spars.

Please do share any further comments/insights you may have.

Warm regards,

Mark (41/59)

starboard lower aft

starboard lower forward

29 December 2013 - 10:29
Join Date: 02 January 2008
Posts: 1547

Dear Mark
Here some further observations referring to swaged terminals.
The swaging process compresses a sleeve around the wire with great force, and this creates narrow slots inside as the sleeve and wire strands partly flow into each other under the high pressure.
Add salt water at the lower end of the shrouds, and an extremely corrosive environment is on hand inside the swage. Stainless steel is susceptible to crevice corrosion, and the conditions in the slots are highly favourable for this type of corrosion.
It would be advisable to flush out the salt water, but this requires drain holes at the lower end of the sleeve. This is hardly possible in practice, and the alternative is to try to prevent the water from getting in.
It was pointed out earlier on this forum that there are two schools of thought regarding the use of mastic in swaged terminals. The well known rigger Brian Toss recommends that terminals are sealed by melting wax into them for keeping the water out.
It would be interesting to test a product named Tef-Gel in this application, as it can be expected to last longer than wax. There are slots in 1x19 wire inside the outer strands, and it would be important to fill these completely to some distance above the upper end of the terminals, say one wire diameter up. In practice this is likely to be quite challenging, as the wire lay opposes being opened.
Any news about your rigging?
Happy New Year!

11 January 2014 - 06:12
Join Date: 10 April 2010
Posts: 32

Dear Lars,

Many thanks for your further observations about pros and cons of sealing the swage terminals and your query about what's happened with the new rig. 

Turns out that the staining was almost definitely caused by contamination on the wire, which ran down and pooled on top of the swage terminal.  In fact, over the last several weeks the staining and pooling had become much less, perhaps suggesting that the contamination had slowly dissipated. 

We were on board over the holidays and took Anthea to the boat yard that did the rerig; the rig was fully inspected by the rigger in the presence of the project manager, a second rig expert and the yard co-owner.  We all agreed the corrosion was both superficial and dissipatiing; apparently this is not uncommon after a new rig is built and put together.  We also confirmed that grit was not used to improve grip, that the swage diameters were checked to ensure conformance with factory specifications, and that the wire was not cut in a manner that caused the strands to separate. 

During the inspection it was determined that the rod backstay was several inches too long - so that was cut shorter and reinstalled; the cap shrouds and aft lowers were also tightened up a few turns as they had worked a little loose since the initial installation. 

The jury is still out regarding sealant on the wire swage terminals connection.  It seems near impossible to ensure a complete seal, which means that any moisture that goes gain entry will remain inside the terminal and eventually cause corrosion.  This seems to be the argument against sealant.  For the moment at least, our plan is to simply rinse the salt off the terminals and leave unsealed.  The suggestion of sealing with wax or TefGel is intriging, but we are just leery about our ability to achieve a total seal. 

Again, thank you for your help in this matter and Happy New Year.




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