What are These Chainplates Made Of?

[sarafina]

We were looking at some of the work we have done with a good friend who is far more knowledgeable and experienced than we are. He looked at our chain plates and made a comment about the metal they were made of and how "Good" they were. He made a point that they were not SS. They are prolly the originals so vintage '67.

I wanted to google what they are made of. Anyone know what the metal might be called?They are a matte silver, dull not shiny, but very smooth to to the touch.

[Blue Stocking]

A bit of a yellow tinge?--Copper/Nickel?

[Bill4]

Originally Posted by sarafina

I wanted to google what they are made of. Anyone know what the metal might be called?They are a matte silver, dull not shiny, but very smooth to to the touch.

Galvanised steel?

[bruce smith]

Originally Posted by sarafina

We were looking at some of the work we have done with a good friend who is far more knowledgeable and experienced than we are. He looked at our chain plates and made a comment about the metal they were made of and how "Good" they were. He made a point that they were not SS. They are prolly the originals so vintage '67.

I wanted to google what they are made of. Anyone know what the metal might be called?They are a matte silver, dull not shiny, but very smooth to to the touch.

monel?

[sarafina]

Originally Posted by bruce smith

monel?

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

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

Thanks,

[Jim Cate]

G'Day Sara,

Not likely to be Monel if they are the original chain plates in a Cal 28. Monel is bloody expensive, and while the good folks at Jensen Marine didn't cut too many corners, use of Monel would be surprising to say the least!

So, have you given them the old magnet test?

Cheers,

Jim

[sarafina]

Nope I haven't. They could be original, I wouldn't be surprised if they were.

That said my little hole in the water was once, back in the day, a racing witch and has been rigged with track all OVER, set marks line the cockpit for different wind speeds, a box of blocks and stuff that I wouldn't even know what to do with came with her, and she had a sail inventory of something like 14 or 16 sails. Life lines were moved inboard 6" to facilitate head sail deployment. She has numerous spinnaker poles/spars.

It's clear she was raced SERIOUSLY. Would that have been a reason for a change to the monel plates?

[Andrew Troup]

I've never knowingly been on a vessel with Monel chainplates but they would have to be just about the best material you could wish for. Get back to us after a magnet test.

I don't think it's a retrofit anybody would be likely to do in the absence of extraordinary circumstances, say they worked for a company which was scrapping some monel flat bar ... it seems most monel finds its way onto boats after being scrapped from chemical plants and the like.

Galvanised steel, if done competently, is also a very good choice IMO, particularly for wooden boats and wooden masts (all mast tangs, cap fitting, etc)

[Therapy]

I thought monel was too soft?

I heard titanium. (another thread)

[barnakiel]

Maybe not monel? Maybe electro polished cast steel?

Why monel for chainplates?

b.

[Stumble]

Originally Posted by barnakiel

Maybe not monel? Maybe electro polished cast steel?

Why monel for chainplates?

b.

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.

[Andrew Troup]

Originally Posted by Therapy

I thought monel was too soft?

I heard titanium. (another thread)

Monel is fine in terms of hardness for chainplate service: not as hard as stainless or titanium (assuming you mean a suitable alloy of titanium - the pure metal about as soft as monel) but similar to mild steel and a lot harder than aluminium alloys (those suitable for marine use).

Aluminium alloy (marine grade) is what the chainplates on any self-respecting aluminium hull will be made of.
Occasionally they are sleeved either with something harder, or with something protective, in very high-class or heavily loaded situations, but this is not usually considered necessary.

It's hard to put comparative numbers on hardness because there are so many alloys of any material, and each alloy is available in a number of different hardnesses, but as a very rough guide (using the Rockwell B hardness scale)

Aluminium alloys from 30 - 55
Mild steel ~60
Monel ~60
Bronze ~75
Titanium ~ 80
Stainless steel 30x 85+

For any material, there is a tradeoff between hardness (which is proportional to tensile strength, particularly for a given material) and toughness. Toughness trumps hardness in this case, hands down (see previous post).

Glass is hard but not tough. It would not make ideal chainplates.

[Andrew Troup]

Originally Posted by barnakiel

Maybe not monel? Maybe electro polished cast steel?

Why monel for chainplates?

b.

Casting is best avoided for highly loaded fittings due to quality control difficulties.

Castings are a project rather than a process.

Once you get the quality sorted for a process it tends to stay sorted, whereas quality issues are specific to each casting, and even to each pour in many cases.

Having said that, cast steel is a fantastic material in the right application, and if the quality is carefully managed. Heavy mobile machinery, for instance, relies heavily on steel castings.

High strength cast steels can be fussy about how they're regalvanised, and how often. A few people have come unstuck with genuine Bruce anchors for this reason, after a number of re-dips.

[Andrew Troup]

Greg Rubin's chart shows an interesting difference between Monel and titanium, at least for the grades he's picked.

Notice the very large delta between yield and ultimate tensile strengths for monel. During this entire phase, the material is resisting brittle failure, absorbing energy by shifting the dislocations in the microstructure. And getting progressively stronger.

If you cut a coupon of monel and leave half of it sticking up out of a vice you'll work up a real sweat smacking it to and fro, each time having to try a bit harder, and you'll likely wear yourself out before it breaks.

G5 Titanium OTOH, as Greg's figures show, has relatively little ability to absorb energy because by the time it yields, it's perilously close to snapping (what he lists as "tensile" is the ultimate tensile stress, at which the material breaks). So although it's a lot stronger, it's not safe to use all that extra strength in an environment of unpredictable but repetitive loading.

[hellosailor]

Monel has been damned expensive for a long time, as is cupronickel in general. I think up to the mid-60's you'd find some fuel tanks made of it, despite the cost, simply because it was so good for a dangerous job. (Ensuring against fuel leaks.)

Now titanium, titanium was always so damned expensive only the military could afford it and it was classed as a "strategic metal" because it is so damned good for so many military purposes, like aircraft cockpit armor. The USSR controlledd most of the world supply of titanium, and it has only been since the USSR fell apart and their supplies came on the global market that mortals have been able to dream or affording titanium. Titanium alloys also like to eat up conventional machine tools by the bulk carton, making it doubly expensive to use.

If you're serious about high strength with small parts or light weight, you go titanium. If you to check your bank balance before you write the checks, and you actually sign them yourself, then you still don't do titanium.

Titanium chainplates? Not damned likely on a production boat.

Hey Greg, don't we all get a family discount from your guys?!