Anchor chain stretch?

[contrail]

Originally Posted by a64pilot

Can you take a picture of it? I’m interested but can’t get what it is in my mind, sorry

I would gladly do so, but have never done so before and have no idea how to attach it or add it to the thread! Advice?


Cheers,
Tim

[a64pilot]

I rarely use the computer to post, but I’ll try.
A the bottom of the page click go advanced, under where you type is a button that says manage attachments, click one of those and chose a picture saved on your computer, be wary of file size though

[Simi 60]

We stretched or deformed 13mm chain on ours during an 80knot event.
Wasn't noticeable to the eye or measurement but the chain from then on always came up twisting and never quite went through the chainwheel as smoothly again.

Felt much better when it was replaced.

[contrail]

Originally Posted by a64pilot

I rarely use the computer to post, but I’ll try.
A the bottom of the page click go advanced, under where you type is a button that says manage attachments, click one of those and chose a picture saved on your computer, be wary of file size though

Sounds simple enough! I will try to remember to take a picture tomorrow. Thanks for the guidance.

[edexter]

Excellent articles on chain in Practical Sailor magazine, if you do your own work you need this publication. See https://www.practical-sailor.com/iss...h_11416-1.html . I get this, Good Old Boat, and Sail, and they are priceless.

[skenn_ie]

I treat chain as being unstretchable. The force required for elasticity to be measurable would pull the fittings out of the boat. Chain needs to lie on the bottom for a substantial length, otherwise it will snatch horrendously.

[sdj]

Try towing a car with a chain and you will get your answer. Don't try this with a car you want to keep.

Chains don't stretch.

[Simi 60]

Originally Posted by sdj

Chains don't stretch.

[Jim Cate]

Originally Posted by Simi 60

Now THAT'S graphic! Nice demo of chain stretch, mate!

Jim

[thinwater]

Originally Posted by Simi 60

Thanks! That's participation.


I wonder how much is stretch of the wire vs. change in bend radius at the end. I'm guessing almost entirely the latter, but probably a little of the former.


I'm guess this was not the chain mentioned just above. What caused this?


Regarding the 80-knot chain, any additional observations?
* Snubber? Describe.
* Chain snatching or steady load? It can be very hard to tel the difference from the cabin in a heavy boat. You would' really feel it, believe it or not (I've taken measurements well over a ton and not really felt it).
* other notable factors? Steap chop? Shallow water?

[evm1024]

Originally Posted by Simi 60

Just looking at the diameter of the wire (eyeballs mk1) it appears that you are right. The majority of the stretch is in the bend radius.It appears that there is very little necking.

[Simi 60]

Originally Posted by thinwater

Thanks! That's participation.


I wonder how much is stretch of the wire vs. change in bend radius at the end. I'm guessing almost entirely the latter, but probably a little of the former.


I'm guess this was not the chain mentioned just above. What caused this?

From this site
https://twoatsea.com/anchor-chain-information-resource/

Regarding the 80-knot chain, any additional observations?
* Snubber? Describe.
* Chain snatching or steady load? It can be very hard to tel the difference from the cabin in a heavy boat. You would' really feel it, believe it or not (I've taken measurements well over a ton and not really felt it).
* other notable factors? Steap chop? Shallow water?

For us in the 80 it was a in behind a low island so not much wave action nor protection from wind for us, but it was a E N/E at 20 and then W N/W at 80.
We noticeably went backwards, veered and leaned over a fair bit, water was coming through windows (since removed and sealed properly) horizontal hail, almost zero vis, sounder lost bottom, GPS lost signal, Radar showed nothing, depth and drag alarms shrieking.
Occasionally we would see a boat drag past.

When it finished and we got GPS back, we were probably the only boat out of about 20 who hadn't moved.

We had moved out about an hour prior when it became obvious we were in line and put 14 ft under our 7ft draft and ran out 150ft for 5:1 (14+7+10 to the deck) of 13mm chain attached to a 150lb manson supreme.
Snubber at the time was 10ft of 1 inch silver rope, so no real stretch.
Since replaced with 20ft of 3/4 inch nylon.

Damage done apart from deformed chain was step treads going from the sides to the foredeck , about 2ft x 1ft x 2inch made of merbau and very heavy that had been held down by gravity had been sucked up and deposited about 10ft fwd on the deck punching holes through the fiberglass skin.
Horizontal hail had found some undiscovered rot in the ply bulwarks and it looked like it was shotgun blasted.
In its path it had blown shipping containers around at the Port and moved passenger jets around at the airport.

Next time well run out more chain.
It does nothing for you sitting in the locker.

[Compass790]

Originally Posted by skenn_ie

I treat chain as being unstretchable. The force required for elasticity to be measurable would pull the fittings out of the boat. Chain needs to lie on the bottom for a substantial length, otherwise it will snatch horrendously.

sorry mate but you are wrong.
It can be stretched without tearing the fittings out even with a mixed chain/ nylon rode. Of course it depends on chain size & quality of rode holding fittings.
I don't recommend the real world test.
See post #43
Agree with longer the rode the better though.

[a64pilot]

Originally Posted by sdj

Try towing a car with a chain and you will get your answer. Don't try this with a car you want to keep.



Chains don't stretch.

Steel is quite elastic, look it up. It’s more elastic than rubber.
Chain does stretch, and it returns to its original dimension if not deformed.
However it’s safe to say that it doesn’t stretch much.
Look, concrete bends, but it doesn’t bend much.

So’ I’ll say again that under any normal anchoring loads, chains elasticity just isn’t a factor, but it does exist.
Ever bounced a steel bearing ball off of a thick piece of steel? It bounces very well, a hammer will bounce nicely off of an anvil too, both are examples of steels elasticity, if it weren’t elastic, it wouldn’t bounce.

By the way, don’t ever let a Blacksmith catch you hitting an anvil with a hammer.

[Steve Bean]

I would love to see a photo of contrail's chain stopper, and a sketch of the installation. As for posting, I suggest asking the nearest twelve-year-old kid.