Outside metal rod

I have a very good book (reportedly a classic) on sailboat rigging:

"The Complete Rigger's Apprentice - Tools and Techniques for Modern and Traditional Rigging", by Brion Toss, International Marine (a division of McGraw-Hill), 1998.

The matter of corrosion of stainless steel fittings is discussed at some length, starting on page 275. Basically, crevice corrosion is the issue. The mechanism is lack of oxygen in confined spaces, such as between a stainless steel fitting and the thing it is bolted or crimped to.

The general solution is to fill such spaces with a compound he calls "slush", which is composed of 6 parts stockholm tar, 3 parts boiled linseed oil, 1 part Japan drier, and 1 part spar varnish. I assume that this is a traditional recipe, handed down in one form or another since the age of sail.

Also widely used is straight lanolin.

I developed a similar trick in the 1970s to slow automobile battery-post corrosion down: I smeared the post and the inside of the clamp with silicon dielectric grease, pushed clamp onto post, and tightened. This ensured that the space between post and clamp was filled with silicon grease, preventing wicking of acid into that space. I should have patented it - now kits to do the same are in every auto parts store. But it seemed too simple and obvious. I bet a thousand people had the same experience.

The author also addresses stress corrosion and metal fatigue, largely in the context of failure swaged connections between fittings and wire rope. The general solution there is slush plus better mechanical details.

Anyway, I'd recommend that people read this part of the book for the practical experience and advice.

Joe Gwinn

Reply to
Joe Gwinn
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Good approach -- but that is "silicon*E*" not "silicon". Silicon is a crystalline substance somewhat like glass except that it is not transparent to visible light. (Silicon and Germanium are transparent to certain ranges if infrared light, however, and have been used to make lenses for IR imagers. (It is also used, in precisely impure forms, to make transistors, rectifiers, and integrated circuits.)

Silicon is a element -- silicone is a family of chemicals in which the silicon elements take the place of carbon in organic chemicals. Thus a grease is possible there, while pure silicon, if crushed to make filler for some other carrier would be very abrasive. :-)

Picture silicon breast implants -- hard as a rock. :-)

So many things that could have (and should have) been patented. :-)

Enjoy, DoN.

Reply to
DoN. Nichols

Saved by the "grease" part?

I do know the difference, but the language is changing.

Oh yes. And lots of nonsense is patented as well.

Joe Gwinn

Reply to
Joe Gwinn

Toss' book is indeed a classic but he does get all nostalgic about old time stuff - in one part of the book he gets rather excited about galvanized rigging - which will last providing that the rigger spends longer wrapping and frapping and slushing with Stockholm tar and whatnot than he did splicing :-)

But stainless rigging really doesn't have a lot of problems with crevice corrosion and all the other mystical stainless corrosions except for the swedged terminals on the lower shrouds which tend to crack around the cable probably due to corrosion between the cable and the swedged fittings although the "screw together" terminals like Norseman don't seem to have this problem.

By the way, the old timey solution to battery terminal was a much cruder version of your silicon grease solution - just gob a handful of chassis grease all over the terminals, cover them up. It worked but is pretty messy :-)

Reply to
J.B.Slocomb

It sounds interesting, and enjoyable reading, because I like that old stuff. Maybe I'll get a chance to look it over. I don't get the International Marine catalogs anymore. Maybe they gave up on me.

But I'll keep it in mind. Anything to do with sailing catches my attention even though I don't do much of it anymore.

Reply to
Ed Huntress

They would be real 'Jugs'. ;-)

Reply to
Michael A. Terrell

You're right about that. He didn't see the reason to spend the money on stainless, but he still told how to do it - he wasn't going to send work away.

He didn't trust stainless to just work, and talked about inspecting by unbolting a few things and looking. He also was not worried about rust stains, but advised to look for surface pitting with a strong light and a magnifier. If there was any pitting, it had to be dealt with, generally with slush (if soon enough) or replacement (if too far gone) or failure would soon be upon us, most likely during a storm.

As for swaged fittings, he recommended dipping the wire end in lanolin or the like before assembly and crimping, precisely to exclude salt water from the interstices of the wire in the crimp barrel. This was especially important in the Tropics.

I used this method for copper wire terminals on my car, only used silicon grease, followed with a heat-shrink sleeve for mechanical strength. This worked well at keeping road salt from destroying the assembly.

All in all, I found Toss's book to be quite practical. And I don't even own a boat, though I grew up with boats.

I do recall that method. But the wisdom of the day was that you should never put grease between post and clamp, because it would interfere with the passage of electricity. I heard this all the time, but I knew that this had to be nonsense because when one clamps pieces of metal together, it's the asperities (little metal hills) that are forced into the opposing surfaces, and the clamping pressure is more than sufficient to push any grease aside, so it ends up surrounding and protecting the asperities, which carry the current.

Joe Gwinn

Reply to
Joe Gwinn

Mammary saps, wot?

Reply to
Larry Jaques

To be honest, I never found anything wrong with swedged stainless rigging except for the cracks in the bottom shroud fittings. I understand that insurance companies suggest that stainless rigging be changed every ten years but I'm not sure of the reasoning. I did replace all the rigging on my last boat, and it was likely more than ten years old, and I noticed that cutting the old rigging cables seemed to take more effort than cutting the new cable but I don't know whether that was work hardening of the old cables or a different alloy in the new :-)

That makes sense (I guess). I replaced the terminals with screw together terminals and filled them full of 5200 before screwing them together and sealant did squirt out around the cable but I don't know how far it penetrated into the cable.

I found it to be very good reading and about the best instructions for splicing, particularly braided rope, I've come across.

Reply to
J.B.Slocomb

They would have to be registered as deadly weapons.

Reply to
Michael A. Terrell

IIRC the standard advice of the time was to use Vaseline, since it did the least harm of all the commonly available greases when accidentally transferred elsewhere such as on the fender paint or your clothes. I don't remember it being very effective at halting corrosion so I tried LPS3, which was somewhat better. jsw

Reply to
Jim Wilkins

That's my recollection as well. What was new was that GE had just released a new product, GE 620, a dielectric grease intended for high-voltage insulators. (Don't think GE makes it any more, but many other do.) This was the game changer. Plus the realization that the grease had to go between post and clamp, versus smeared on the outside.

Joe Gwinn

Reply to
Joe Gwinn

I've always used axle grease on battery terminals. It doesn't melt and run out of the terminal, like some other types.

Reply to
Michael A. Terrell

[snip]

Toss does discuss this. It's the accumulation of fatigue and various kinds of corrosion slowly eating away at the safety margin. Not to mention becoming brittle from work hardening. Everything looks OK, but will break in a storm, just when it's most critical that it not break.

The steel has not likely gotten worse. Most likely, the cables are work hardened, as you suspect. Another reason for periodic replacement.

I assume that you mean 3M type 5200 sealant. This is listed for fiberglass and wood, but 3M does not mention use for metal. I would also guess that 5200 is too thick to penetrate through the wire rope. So, there may be little protection in this, as the saltwater can wick down the center of the rope.

Oh yes. And I have made some braided eye splices to make a nylon rope handrail for the basement stairs, which are too narrow for a traditional handrail. Just like on a boat. Used marine hardware for the attachment points as well, for the guaranteed strength (real full-penetration welds, not slapdash partial resistance butt welds), with the hardware screwed directly to the studs through the wallboard.

Joe Gwinn

Reply to
Joe Gwinn

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