Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 29-09-2020, 10:42   #1
Moderator
 
carstenb's Avatar

Cruisers Forum Supporter

Join Date: May 2012
Location: At sea in the pacific - 5 years full time blue water cruising
Boat: Jeanneau Sun Fast 40.3
Posts: 5,408
Images: 1
Can Dyneema Chafe through Stainless Steel? Yes!

The picture below shows the stainless steel eye of our snubber. Note the 3 deep furrows in the steel. These have been caused by chafe from the Dyneema shackle we use to fix the snubber to the anchor.

The snubber and shackle have been used for slightly over 1000 nights at anchor i various anchorages around the world. The Dyneema shackle is the original shackle and note that there is no wear on the Dyneema.

For the curious, we have a 30 kilo Mantus anchor - 100 meters of 8mm chain and our boat weighs in at about 12 tons, fully loaded.
Attached Thumbnails
Click image for larger version

Name:	DSCF2451.jpg
Views:	1092
Size:	430.8 KB
ID:	224355  
__________________
I must go down to the seas again, to the lonely sea and the sky,
And all I ask is a tall ship and a star to steer her by

www.svcapri.com
carstenb is offline   Reply With Quote
Old 29-09-2020, 11:27   #2
Registered User
 
flyingnut40's Avatar

Join Date: Jan 2014
Location: Cobourg, Ontario,Canada
Boat: Sandpiper 565
Posts: 281
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Following with interest
__________________
Live your life with passion, even if it kills you, because something is going to kill you anyways. Webb Chilies
flyingnut40 is online now   Reply With Quote
Old 29-09-2020, 11:38   #3
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 14,070
Images: 14
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Any chance that whilst it's in use the stainless steel could touch the galv chain?
Pete7 is offline   Reply With Quote
Old 29-09-2020, 12:33   #4
Moderator
 
carstenb's Avatar

Cruisers Forum Supporter

Join Date: May 2012
Location: At sea in the pacific - 5 years full time blue water cruising
Boat: Jeanneau Sun Fast 40.3
Posts: 5,408
Images: 1
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Quote:
Originally Posted by Pete7 View Post
Any chance that whilst it's in use the stainless steel could touch the galv chain?
yes, I suppose it could. If the shackle twists when we turn whilst at anchor (wind, swells etc) there is that possibility - but I don't think the chain would be in contact with the eye for any great length of time.

What are you thinking? some type of galvanic corrosion?

I have to say, the Dyneema fits exactly into the groves.....................
__________________
I must go down to the seas again, to the lonely sea and the sky,
And all I ask is a tall ship and a star to steer her by

www.svcapri.com
carstenb is offline   Reply With Quote
Old 29-09-2020, 17:46   #5
Registered User

Join Date: Aug 2020
Location: Stuck in Melbin
Posts: 19
Images: 5
Re: Can Dyneema Chafe through Stainless Steel? Yes!

I wonder if it is more like crevice corrosion, not the chafing so much as the Dyneema providing a means for moisture and salt to be in close contact with the steel for a long time. The thimble may be stainless but perhaps a low grade alloy?

Given you use it frequently, if it was chafe alone I would expect the abraded area to be bright with wear. How about a forensic pic, scrape out some of the corroded metal and see how deep it goes and what it looks like really close up.


Thanks for sharing, never seen this before.
tanngrisnir is offline   Reply With Quote
Old 29-09-2020, 20:28   #6
Writing Full-Time Since 2014
 
thinwater's Avatar

Cruisers Forum Supporter

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 7,521
Re: Can Dyneema Chafe through Stainless Steel? Yes!

That's not chafe, that's some manner of electrochemical corrosion. The mechanism is not jumping out at me, but the pattern is all wrong for chafe. It is too rough and it obviously happened in a very short time period, relative to the total time at anchor. I've seen corrosion like that on stainless in chemical plants.


The other thing is that there is VERY little motion when the shackle is under load.


A high res photo would help.
__________________
Gear Testing--Engineering--Sailing
https://sail-delmarva.blogspot.com/
thinwater is offline   Reply With Quote
Old 29-09-2020, 20:44   #7
Writing Full-Time Since 2014
 
thinwater's Avatar

Cruisers Forum Supporter

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 7,521
Re: Can Dyneema Chafe through Stainless Steel? Yes!

a. Was the snubber typically in the water or above? I'm assuming above.



b. I'm guessing the boat was often anchored in this manner for extended periods, for example at least weeks?
__________________
Gear Testing--Engineering--Sailing
https://sail-delmarva.blogspot.com/
thinwater is offline   Reply With Quote
Old 30-09-2020, 07:21   #8
Moderator
 
carstenb's Avatar

Cruisers Forum Supporter

Join Date: May 2012
Location: At sea in the pacific - 5 years full time blue water cruising
Boat: Jeanneau Sun Fast 40.3
Posts: 5,408
Images: 1
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Quote:
Originally Posted by thinwater View Post
a. Was the snubber typically in the water or above? I'm assuming above.

The snubber is always below the water. the bridle si about 5 meters long so the eye will always be submerged.

b. I'm guessing the boat was often anchored in this manner for extended periods, for example at least weeks?
we have anchored for extended periods - Nuku Hiva - say 6 months in one stretch. Hawaii, the Big Island - say 6 weeks in one spot. Many other places 3 weeks at time, Fakarava, Kuenhi, Rangiora, Rareteria etc.

While in polynesia we spent over 18 months at anchor in various places - never tied to a dock or a mooring ball during those 18 months.
__________________
I must go down to the seas again, to the lonely sea and the sky,
And all I ask is a tall ship and a star to steer her by

www.svcapri.com
carstenb is offline   Reply With Quote
Old 30-09-2020, 09:09   #9
Writing Full-Time Since 2014
 
thinwater's Avatar

Cruisers Forum Supporter

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 7,521
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Quote:
Originally Posted by carstenb View Post
we have anchored for extended periods - Nuku Hiva - say 6 months in one stretch. Hawaii, the Big Island - say 6 weeks in one spot. Many other places 3 weeks at time, Fakarava, Kuenhi, Rangiora, Rareteria etc.

While in polynesia we spent over 18 months at anchor in various places - never tied to a dock or a mooring ball during those 18 months.

Thank you for the reply. This is still baffling, since chafe of this type is unknown, and Dyneema is in very wide use. Certainly, this is the result of something other than simple chafe. The pattern is wrong and the stainless is (appears to be) rough and rusty, which does not add up, not one bit. There are skips in the wear, which does not happen with chafe. I think it is obvious that there is some other factor involved, either odd metalurgy, a surface hardening effect (I've seen this is cold rolled steel) or something electrochemical, but for now it is a mystery. I'm leaning towards some factor relating to how the steel was rolled and formed.



Did you observe this happen slowly, at a steady rate, over a period of years, or did you notice it only recently?
__________________
Gear Testing--Engineering--Sailing
https://sail-delmarva.blogspot.com/
thinwater is offline   Reply With Quote
Old 30-09-2020, 09:25   #10
Registered User
 
OS2Dude's Avatar

Join Date: Nov 2014
Location: Atlanta, GA
Boat: Catalina 30
Posts: 371
Images: 5
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Are you sure the thimble is solid stainless steel? It looks like it could be plated steel. The shiny part seems to be the only part that is worn (and it is shiny on the sides of the furrow), and the rust seems too dark to be stainless corrosion.
OS2Dude is offline   Reply With Quote
Old 30-09-2020, 09:38   #11
Registered User

Join Date: Apr 2012
Posts: 272
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Quote:
Originally Posted by carstenb View Post
The picture below shows the stainless steel eye of our snubber. Note the 3 deep furrows in the steel. These have been caused by chafe from the Dyneema shackle we use to fix the snubber to the anchor.

The snubber and shackle have been used for slightly over 1000 nights at anchor i various anchorages around the world. The Dyneema shackle is the original shackle and note that there is no wear on the Dyneema.

For the curious, we have a 30 kilo Mantus anchor - 100 meters of 8mm chain and our boat weighs in at about 12 tons, fully loaded.

Don't know why this would come as a surprise. Rubber seal lips will eventually wear a grove in a steel rotating shaft. That is why the rear main crankshaft seal of an engine starts leaking.
Physics, interesting stuff.
Good luck with your advantures!
oleman is offline   Reply With Quote
Old 30-09-2020, 09:38   #12
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 14,070
Images: 14
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Quote:
Originally Posted by carstenb View Post
What are you thinking? some type of galvanic corrosion?
Certainly something odd and as others have stated, I would have expected smooth possibly polished grooves.

Going forward, I think cut the splice off and replace with a good quality stainless thimble if you can find a well known make. A galvanised thimble won't do, the Dyneema will be through that in a week.

Well spotted though.

Pete
Pete7 is offline   Reply With Quote
Old 30-09-2020, 10:19   #13
Registered User

Join Date: Oct 2019
Location: Frederick, MD
Boat: Beneteau Oceanis 40
Posts: 82
Re: Can Dyneema Chafe through Stainless Steel? Yes!

If you abrade the thin oxide layer that protects stainless in the absence of air it will corrode. Stainless only remains 'stainless' if the oxide layer is intact.
vpbarkley is offline   Reply With Quote
Old 30-09-2020, 10:51   #14
Writing Full-Time Since 2014
 
thinwater's Avatar

Cruisers Forum Supporter

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 7,521
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Quote:
Originally Posted by Pete7 View Post
... A galvanised thimble won't do, the Dyneema will be through that in a week....
Pete

Nope. If this were even slightly true, he would have worn through the chain during some of the longer stays. No, this is just not something that is seen.


This is not wear. This is corrosion. It doesn't even look like wear. There was no movement. I've done wear testing of Dyneema on stainless (reciprocating chafe machine) and it looks nothing like this.
__________________
Gear Testing--Engineering--Sailing
https://sail-delmarva.blogspot.com/
thinwater is offline   Reply With Quote
Old 30-09-2020, 12:02   #15
Registered User

Join Date: Aug 2014
Location: Palm Beach Gardens, FL
Posts: 45
Re: Can Dyneema Chafe through Stainless Steel? Yes!

Does a magnet stick?
Var Korall is offline   Reply With Quote
Reply

Tags
dyneema, stainless steel, steel

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Dyneema rigging replacing stainless steel Miki Construction, Maintenance & Refit 5 08-01-2019 07:29
Chafe protection through fiberglass... best solution? basssears Electrical: Batteries, Generators & Solar 25 24-03-2018 10:33
Replacing stainless steel centerboard control cable with dyneema? autumnbreeze27 Deck hardware: Rigging, Sails & Hoisting 9 11-08-2015 03:02
Welding Stainless Through-Hulls to a Steel Hull Boracay Construction, Maintenance & Refit 30 20-06-2010 00:06

Advertise Here


All times are GMT -7. The time now is 19:33.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.