Rust staining on shroud & fitting - advice sought

[JimC]

I have rust staining of one (only) of my shrouds where it enters the swage above the turnbuckle. It extends for an inch or so above the swage. Further up the wire there are no traces of staining so it isn't running down from above. This particular shroud passes very close to a guardwire and, suspecting that this might be a factor, I insulated the guardwire with tape but it made no difference.

The staining cleans off easily with oxalic acid and the underlying metal looks fine except that, on examining with a magnifying glass, there is a tiny depression like a crevice on one of the wires, just visible in this enlarged photo, about 1/4 way down the picture

I had hoped to get another couple of years out of my standing rigging, it's only had 9 years use and the boat hasn't been sailed hard, but obviously I'll replace the shroud if it's deemed unsafe and, if doing that, might as well replace all the lot. I wonder would saturating the wire with ACF50 do any good? I've found this product very effective in dealing with other corrosion issues. Any advice most welcome.

 

[vyv_cox]

I think that what you are experiencing is crevice corrosion. Shrouds quite often appear rusty due to minute cracks that are produced during the forming process. The standard way to improve this is by polishing with an abrasive product. In your case it seems that the crevice is much larger and polishing is unlikely to remove it. You could try something to prevent contact by seawater, for example grease or Waxoil. I don't have any experience with ACF50 but it's worth a try.

The mark is not in a high stress position and seems unlikely to be a fatigue initiator but keep an eye on it. Failure will be very obvious as the strand will stick out.

 

[JimC]

Thanks Vyv.

 

[Caer Urfa]

Hi Jim

Sorry mate put it this way I would not be happy sailing offshore with that rigging, blowing up your pictures shows fatigue has already well started
and my advice would be to replace it, why take a chance as if/when it parts you will have a load more problems !

Mike

 

[Sailingsaves]

I used to spray my rigging with this:

super molybdenum disulphide

http://www.opieoils.co.uk/p-69369-gulf-multiauto-super-molybdenum-disulphide-lubricant.aspx

What does Vyv think of this idea?

 

[Bosun Higgs]

molydisuphide is a horrible black gunge, a lubricant not a rust preventer. get that on your rigging and you will be for ever cursing it getting onto clothes and sails and ropes.

stainless steel isnt entirely stainless in reality whcih makes a nonsense of the german name of rostfrei. That it isnt. But the corrosion you have got there is the worst that I have seen and makes me wonder what is going on inside the swage. It could be crevice corrosion but it could be a number of other things. I wouldnt hesitate to change the shroud. Leaving aside the issue of masts and insurance, a failure at sea could put your life at risk

 

[Sailingsaves]

molydisuphide is a horrible black gunge, a lubricant not a rust preventer. get that on your rigging and you will be for ever cursing it getting onto clothes and sails and ropes.

stainless steel isnt entirely stainless in reality whcih makes a nonsense of the german name of rostfrei. That it isnt. But the corrosion you have got there is the worst that I have seen and makes me wonder what is going on inside the swage. It could be crevice corrosion but it could be a number of other things. I wouldnt hesitate to change the shroud. Leaving aside the issue of masts and insurance, a failure at sea could put your life at risk

The spray is excellent and not a gunge. Yes it is a lubricant but also...

"Super Molybdenum Disulphide Lubricant is a specialist lubricant designed to extend the life of wire ropes, cables and chains...and forces water out of metal pores"

It sprays on as a mist, penetrates and dries. Once dry it does not rub off and tiny amounts are needed. It is designed to get into pores and repel and dispel water and therefore prevent crevice corrosion. What Vic suggested would be excellent on NEW rigging, but would it not trap water inside that is already there? I used to spray it just an inch above the swage fittings and I believe it helps lengthen the life of the rigging (where most trouble occurs - swaged terminals - with standing rigging - as you say stainless is not rust free - as well as crevice corrosion, stainless NEEDS air to 'keep it working' which is why a swaged terminal with a puddle of salt water in there is not good and we have all heard of stainless rudder socks failing inside rudders)

The first thing I did when I bought my first boat was renew all the rigging and oversize the forestay (within foil) as a matter of course.

I don't remember if the OP stated this was a cap shroud etc or a not so important lower shroud.

I reckon Vyv knows his stuff though.

 

[JimC]

I don't remember if the OP stated this was a cap shroud etc or a not so important lower shroud.

It's a cap shroud.

 

[William_H]

OP used the term "only 9 years of use." SS wire in my experience fails from calender period after first use. ie not related to actual sailing time or abuse. So if it is around 15 years or more old change it all. Certainly the smaller 3/16 wire is more susceptible but larger size also. olewill

 

[KINGFISHER 9]

A bottle of Spotless Stainless ... paint it on, wash it off = just like new!

 

[Biggles Wader]

Hi Jim

Sorry mate put it this way I would not be happy sailing offshore with that rigging, blowing up your pictures shows fatigue has already well started
and my advice would be to replace it, why take a chance as if/when it parts you will have a load more problems !

Mike

Agree.The fact that you have taken the trouble to photo it and ask on here suggests that there is enough doubt in your mind to warrant changing it.You wont be happy with it until you do.