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Old 09-06-2008, 13:29   #16
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Just for what its worth, even "good" grades of stainless can rust because of free iron molecules at the surface left by the fabrication process. Stainless products subjected to corrosive applications are typically passivated to clean and remove the free iron.

Most passivation is performed with a nitric acid based solution although some others are used, even citric acid.

There is more to corrosion resistance than just the alloy.

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Old 09-06-2008, 13:49   #17
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There is more to corrosion resistance than just the alloy.
Good point. You should also be careful as to any contact with dissimilar metals. Every contact point needs to isolated. To further add protection against corrosion, we use Tef-Gel on every single fastener. It's basically common sense, do it right and do it once. Take the time to apply Tef-Gel, isolate other metals and ensure that it is in fact 316, and you won't have to worry about it for decades.
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Old 09-06-2008, 14:20   #18
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You'll see 304 and 303 used on a lot of the lower cost boarding ladders. It's common and OK for fresh water but shows rust easily and after a short season in salt water. It has very good strength and is easier to work with but is not perhaps what you think it is. The price difference is more than significant. Triple priced is not out of line. When it's new there is a better polish on most 316 pieces. It is also part of the process to finish it smoother for better rust prevention. It's not assured but again it usually looks a bit better and is desirable.

If they are not making a big deal about it being 316 then it almost certainly isn't. On those nice huge sport fish boats you can be looking at many 10's of thousands of dollars in just the stainless work.
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Old 10-06-2008, 07:50   #19
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If they are not making a big deal about it being 316 then it almost certainly isn't.
Yep, and for many of the reasons that have been pointed out in this thread; looks better, lasts longer, more suited to a salt water environment, etc.
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Old 12-06-2008, 13:04   #20
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One thing that seems to have been missed here regarding the 300 series stainless steels is the addition of 2 to 3 % molybdenum to 316/316L, which gives it a much higher resistance to chlorides among other things. 316 also has less chrome than 304, (16-18%) and more nickel (10-14%), making it even less magnetic. It's resistance to chloride ions (the villain in stagnant sea water) is higher but generally it's mechanical strength is slightly lower, although the minimum required tensile strength, and yield strength are the same for both alloys. For areas where severe chemical attack will make even 316 fail, 317 with higher chrome, higher nickel and even higher molybdenum is both very expensive, and almost impervious to salt water. One would only need it in rare circumstances where design caused problems led to failure of lesser metals. Keel bolts on certain designs come to mind. Such an expensive repair that one shouldn't fret about $100 more for raw materials.
The duplex stainless steels, so called because they are both Austenitic and Ferritic, contain large amounts of chrome, (typically 22% or more), but more importantly contain a generous amount of molybdenum combined with a helping of copper which give them excellent resistance to chlorides and very good strength, in the case of 2205, almost 100,000 PSI. compared to the 70, 000 of the 300 series. None of the austenitic stainless steels are hardenable by heat treatment, and all will work harden severely, so once it has been cold formed, or forged it will be quite hard, and prone to cracking. This is the bugaboo with swaged wire terminals in the rigging, as they have been heavily worked in the swaging process, and so quite hard and prone to cracking, right where a little flexibility is an asset.

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Old 30-06-2008, 12:19   #21
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Just a quick bit of information about joining differing types of metals to avoid galvanic(rust) reactions. I'd come across this the other day when researching about the carbon fiber being used here. And most here (at work) were unaware of it. Good to know what you need to watch out for since most of us do our own repairs. Probably common knowledge, but thought I'd throw it out there.

There are 3 possibilities for all materials:
1. That a dry installation is allowed(meaning that no barrier gasket type material is needed)
2. Wet installation is required(be it a coat of 3m5200, butyl tape, or something more substantial to reduce electrical contact we use hysol ea934 or 9394na for carbon fiber. )
3. Prohibited (watch the daily progess as is eats itself up)



For Al to AL joints
1 aluminum (anodized), Cad. plated Steel, Cad plated Monel
2. Titanium, CRES(C orrosion RE sistant S teel commonly called stainless)
3. Monel, Copper, Brass

For TI to TI, Cres or Ni alloys in any combination
1. Ti, CRES, Inconel
2. Monel
3. Al coated steel, Cad plated steel, Cad p[lated Monel, Aluminum


For Al to CRES
1. Plated (AL or Cad) titanium
2. A286, Cad. Plated Monel, Unplated Titanuim
3. Aluminum

For Al to Steel
1. Cad plated steel, Cad. plated monel, Cad plated CRES
2. Titanium, CRES
3. Aluminum

For Al to Ti
1. None
2. Titanium , CRES
3. Cad plated Steel, Cad plated Monel, Monel

For Carbon Fiber Composites to all Alloys
1. NONE
2. Titanium, Inconel, CRES, Monel
3. Aluminum, Cad. plated Steel, Cad plated Monel

And just a note to those who are working or want to work with carbon fiber, we currently use rivets from A-286 steel with a rust preventative coating per mil-l-46010 sometimes called par-90. These are normally for aerospace and extremely expensive, but there is probably a marine equivalent. And the problem is from the charge of the carbon in the carbon fiber, standard fiberglass doesn't contain carbon so is not an issue.
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Old 01-08-2008, 17:05   #22
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Hello everybody.
I have a question about SS rigging. In a 22 year old boat (trimaran) how bad can the SS cables suffer from fatigue. Where this fatigue can occur ? Only on the shrouds, stays etc... ends - I mean - the place where turnbukles, chain plates terminals and similar joins to the cable or the cable itself can also suffer from fatigue ? If I cut off all terminals, and put new ones, can I trust the cable ? Thank you for any answers about this.
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Old 02-08-2008, 04:12   #23
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... In a 22 year old boat (trimaran) how bad can the SS cables suffer from fatigue. Where this fatigue can occur ? Only on the shrouds, stays etc... ends - I mean - the place where turnbukles, chain plates terminals and similar joins to the cable or the cable itself can also suffer from fatigue ? If I cut off all terminals, and put new ones, can I trust the cable ?
I’d be very wary of spending much money replacing expensive fittings on 22 year old standing rigging. The wire may (likely) be very near the end of it’s safe useful life.

Both wire rigging and fittings have finite lives. They both fall prey to fatigue and corrosion over time. Wire rigging, due to its construction and method of attaching fittings, will probably fail from corrosion; whereas fittings fail primarily due to fatigue.

Corrosion in standing rigging is primarily "chloride type" corrosion, where salt water in an oxygen free environment will "activate" the stainless steel, and cause it to eat itself. This happens inside swage fittings, with little obvious evidence, until the wire and fitting part. Sometimes a small crack will be apparent in the swage fitting, from the corrosion expanding the parts, and sometimes not. Careful inspection can often find problems, and if any wire strands are broken at the shank of the swage, the wire should be replaced immediately. Type 316 stainless steel is only marginally better protection from this "active" type corrosion, than is 302/304 stainless.
Nitronic 50 rod, which is the alloy used for most rod rigging, is quite corrosion resistant and most of the fittings are designed to drain, thus avoiding the problem.

Anaerobic corrosion also causes surface discoloration on the wire itself. Any type of coating on the wire surface (dirt, oil, salt, and other surface contaminates) can keep oxygen from coming in contact with the surface of the stainless steel. If oxygen can not reach the surface of the stainless steel, the surface can not "passivate" itself, and corrosion or staining can occur. This can in all types (316 and 302/304 ss), and sources (US and imported) of stainless steel wire. The only way to avoid this staining is to keep the wire clean.

Fatigue is many times less evident than corrosion, but equally deadly to the vertical orientation of the rig. Wire is superior (over rod) in indicating fatigue, in that one or more stands will usually break (meathooking) before the entire bundle fails. Fatigue usually occurs during use of the boat, but a loose stay or shroud flogging in the wind at the dock is also a prime candidate.

According to Torrensen Marine (“Sailing News”)

“... In a fresh water environment with moderate humidity and negligible salinity, the life expectancy of the average standing rigging system is 15-20 years.

In a northern coastal environment with moderate humidity and moderate salinity the life expectancy of average standing rigging system is 10 to 15 years.

Lastly, in a high humidity and high salinity environment the life expectancy is more like 5 to 10 years ..."


Goto: Standing Rigging; You Can’t Ignore the Wire: Torresen Sailing and Boating News » Blog Archive » Standing Rigging; You Can’t Ignore the Wire
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Old 02-08-2008, 07:01   #24
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Thank you GordMay. Your words were very helpful and makes very good sense. The problem is that I am under negotiation over a 22 years old trimaran and the present owner knows very litle about the boat. He knows that the boat was built in 1986 but does not know if the rigging was replaced.. The price that he is asking (105.000 Brazilian currency – equivalent to US$ 70.000) becomes to expense if I have to change the all standing rigging. Thus my question about SS cables. The boat is a Marples trimaran CC44. Thank you once again.
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Old 02-08-2008, 07:18   #25
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Hi Luis. Check out this link it might help.

Sailboat Rig Problems - J. Stormer
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Old 02-08-2008, 12:38   #26
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Dear friend. Mrgan,
The link is really first class. Very, very helpful. Thank you very much.
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