What are These Chainplates Made Of?

[sarafina]

I got a magnet and tested.

The chainplates are non-magnetic. The bolts holding them are non magnetic. I am not sure what that tells me as both marine stainless and monel are supposed to be non magnetic.

I asked our friend, who originally mentioned this to us, why he was so sure it was monel.

He said you could just tell by the look and feel of it. Not exactly scientific...

Here is another confusion... The standing rigging is magnetic. Most of the screws and nuts and bolts in my hardware stash, which I purchased at marine supply are magnetic. A bunch of the screws are ones I have removed from on the Cal, which have been in place for the 50 years of the boat's life and are corrosion free, but are magnetic.

I came away from the boat feeling pretty puzzled...

[CeesH]

Originally Posted by Stumble

Monel is a copper nickle alloy, that is generally used in highly corrosive environments, and where you need a high strength metal. It is generally in the same strength class as the 300 series stainless steels, but does have better general corrosion properties. It's down side is that it is more anodic than 300 series, and subject to galvanic corrosion.

It is also a very expensive material, about on par or more expensive than titanium, but without titaniums advantages.

A quick chart:


....................yield..............tensile
Mild steel.......50,000psi......70,000psi
304...............31,200psi......73,200psi
316...............34,800psi......79,800psi
Monel............42,000psi......87,000psi
G5 titanium..128,000psi....138,000psi

Weight wise, Monel and all the steels are within just a percentage of the same weight, with titanium running about 40% the weight by volume.

15-5PH ~ yield.....145,038 psi; tensile....155,190 psi

15-5PH and 17-4PH are Magnetic Stainless

my 2 cents..

[Bash]

Originally Posted by sarafina

That's it! Monel. Cool, now I can go google it!

Do others hold the opinion that it's "good stuff"?

Thanks,

Not just the "good stuff." Often the best stuff. Especially when electrolysis is concerned.

[Andrew Troup]

Sarafina

Like most simple dictums, the one about marine stainless being magnetic is true except when it's not.

The times when it's not include the precipitation hardening steels mentioned by CeesH: this is mainly found on sailboats in the form of premium or ultrapremium shackles and snapshackles, as it's stronger.

It's important not to use such shackles for prolonged service immersed in seawater. They do a lot worse than, say, 316, which itself is far from ideal in such situations (especially quiet seawater)

Other stainless alloys which are eminently suitable for marine use, but nevertheless magnetic, include duplex and superduplex stainless, the best known of which is SAF2205. These can be used underwater, boasting better resistance to pitting than 316. It's also stronger AND tougher (a rare and attractive combination), and what tops it off: it's surprisingly affordable, often more so than 316, if you go to the big stockholders who supply the industry.

I first encountered magnetic stainless during a calm-weather outing on a luxury cruising sailboat on which, in my youth, I served as sailing master. The autopilot started acting up. If the boat gave a sudden roll when motoring - say we encountered a wake, in flat water - the pilot would pile in and steer exactly the wrong wiggles to make things as worse as possible.

Although it didn't happen when sailing, so strictly speaking it wasn't my problem ;-)

... eventually I discovered that someone had put a leatherette pack of conical, flat bottomed, thin stainless whisky tumblers in the sink to stop them rolling onto the floor. As they rolled about the sink, as only conical things can do, they played merry hell with the fluxgate master compass for the autopilot, which the builders had (for unfathomable reasons) installed under the sink.

This was a stupid thing for them to do even in the unlikely event the boat was 'dry', because cutlery stainless is invariably -- to a close approximation -- magnetic.

It was also a surprising thing for the vessel's owner to have done. I say this because he was a captain of industry - in his case, a specialised supplier and fabricator of stainless steel ! He was greatly surprised when I brought them up into the cockpit and waved them about the steering compass, demonstrating that they were strongly magnetic. "But .... they're STAINLESS", he protested.

Even 30x series stainless (eg 304, 316) can be mildly magnetic, if it's strain hardened (aka work hardened). This will be the case for forged or swaged items.

I hope I've cast some light, rather than muddied the waters. It's a fairly convoluted topic.

[Jim Cate]

In particular, 304 can become somewhat magnetic when it is cold formed or drawn. Thus wire which is drawn and many screws and bolts which are cold headed and have rolled threads can be picked up with a magnet... except when you have dropped them into the bilge or other inaccessible spot!

Actually Sara, the reason that I suggested the magnet was to rule out any form of mild steel with some sort of surface treatment that looked like monel or whatever!

Cheers,

Jim

[CeesH]

About 17-4PH and 15-5PH

Originally Posted by Andrew Troup

...........................................The times when it's not include the precipitation hardening steels mentioned by CeesH: this is mainly found on sailboats in the form of premium or ultrapremium shackles and snapshackles, as it's stronger.

It's important not to use such shackles for prolonged service immersed in seawater. They do a lot worse than, say, 316, which itself is far from ideal in such situations (especially quiet seawater)......................................

If have used these materials for over 25 years to design and produce "sound source devices" for the use of deep sea seismic exploration. These devices are towed behind a seismic exploration vessel at about 5 meters under the water surface. These devices were used 24/7 and had a life time of about 8 to 10 years in this hars salt water envirioment.

Operators like Seismograph Service London Ltd (Former Rhatheon company) and Western Geophysical Corp. (a former Litton company) have used these devices in the '80 and '90.

CeesH

[Stumble]

HelloSailor,

Surprisingly the cost of titanium has come down pretty significantly in the last ten years or so. Primarily as a result of a new smelting method that has allowed the industry to reduce the number of steps, time, and harsh chemicals used in the extraction process.

Honestly prices get a little tricky because we typically make so many fewer of a part than the stainless manufacturers, and because there is often some engineering issues to make the switch reasonably.

So for instance our 1/2" turnbuckles run about $150 retail, compared to a Johnson 1/2 one. So obviously if you replace ours part for part it's going to be a premium. On the other hand ours are rated to a nominal strength of about 60,000lbs vs theirs at 10,000lbs. Now you could replace size for size, but the smarter way is to buy a turnbuckle properly sized for strength. Where the price is much more comperable.

We are currently working with a prominent sail hardware company to try and design parts that would be strength replacemnets instead of size replacements, and hopefully will have parts on the market early next year that will be much more price competitive.


Even given this there are parts right now that are price competitive right now with stainless steel. Lifeline stantions particularly we can provide for around $60 each, compared to stainless that retail for $99 each. Ours however are roughly three times as strong, and half the weight.

[Andrew Troup]

CeesH

The problems in prolonged submersion arise from oxygen starvation, leading to crevice corrosion and followed by stress corrosion cracking.
Oxygen starvation is not however a factor for an item which is continually on the move (eg being towed). It's also not a particular problem if a precipitation hardening material is not hardened to the upper range of potential tensile strength, but high strength sailboat shackles invariably are.

Wichard, for one, recommend against using their precipitation hardening shackles for moorings and such, in fact anything in quiescent seawater.

I was first alerted to this by some serious failures of 17-4PH in relation to mooring bottom connections, in comparison with 316 fittings immediately adjacent, which held up better. When I researched it, I found that this was in keeping with the expectations under the prevailing conditions.

[hellosailor]

Sara-
'He said you could just tell by the look and feel of it. Not exactly scientific..."
Actually, QUITE scientific. He's just not expressing himself very well. There are differences in the color, the lustre, the finishes, the grain structure, of different metals. In the same way that you can tell the difference between a brass handrail and a wrought iron one, there are more subtle differences that tell you aluminum/vs/steel, or monel versus something else. Or at least "monel-ish" versus something else.
Some of the differences are things that most folks would be hard pressed to put into words, like whether a metal feels warmer or colder to the touch. And I suspect there are some galvanic reactions, differences in the current flow across the nerve endings, that we just don't have common terms for. Maybe "tingly".

It might be *simpler* for most folks to put a sample in a machine and have a result spit out, but someone who knows their metals can often tell them apart, the way a trained eye can tell "this is a diamond, this is a cubic zirconium". Try explaining to someone how you can tell them apart--assuming you're one of the folks who quickly can. Some just can't.

Hey, is this milk sour? <G>

[sarafina]

That's interesting.. one of the things he said that I didn't pass on because it sounded so new age is "It has an aura all it's own"...

And I can "get that" about being able to "just tell" something...

... dump a pile of fabrics in front of me and I can tell you all sorts of things about them that most people wouldn't "see"...

So stainless may or may not be magnetic. It just depends. *sigh*

[Paul Mazza]

Sara, could your Cal 28 any chance be the old Debinda 2. It was a boat that was raced very successfully in the late 1960's in the Danforth series off of San Francisco. If it's her, you may have some very unique hardware on board.

[drdivot]

Paul my name is Ken Schaefer and my dad owned Debinda 1 thru Debinda 4 and was a member at Richmond yatch club. If you have any information about his boats i would love to hear it

I was 10 when he sold his last boat and died in 1974 so I am very curious.


Thanks
Ken Schaefer

[Paul Mazza]

Ken, sorry but I don't have much additional information. When I was young a sailing friend of ours sailed (I believe) on one of your dad's boats. I responded to Sarafina's post regarding the apparent exotic chain plates on her Cal 28 because of the unique position this crew member of your dad had. I never heard back from Sarafina, so don't know if her boat is the Debinda I was referring to.
Here's what I remember. Our friend, who's probably passed on by now was named Jim Frasier. He sailed with a crew of big, heavy weight guys on your dad's Cal 28 (I believe Debinda 2). I remember they won the Danforth Trophy, which was part of the SF Bay Ocean Racing series in the 1960's or possibly very early 70's. They were the tiny giant killer in the fleet and had no business beating the big ocean boats. But they sailed her very hard and very fast. The significant thing about our friend Jim was, he was in charge of the local naval air apprenticeship program, and thus had access to a great machine shop. He'd occasionally have the apprentices make hardware for the race boat. It was during the Vietnam war, and the exotic materials were being thrown away by the Navy in those days, and the apprentices were learning valuable skills, so it was a win/win situation. A friend of mine was an apprentice there, and said this training was some of the best he had, and I know for a fact, he became one of the finest machinists I ever knew. Unfortunately that's all I know/remember. Paul