Stainless steel anchors - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 14 Old 09-08-2011 Thread Starter
PCP
Senior Member
 
PCP's Avatar
 
Join Date: Dec 2004
Location: Portugal, West Coast
Posts: 16,214
Thanks: 21
Thanked 105 Times in 88 Posts
Rep Power: 11
 
Stainless steel anchors

Stainless steel anchors are a beauty, they are expensive but most of all I thought that they were weaker than their steel model. I thought that a good high grade steel was always more resistant to breaking and torsion than any stainless steel but then I saw this add on the net:

" Breaking loads 50% to 100% higher than galvanized anchors of competitors."

Stainless Steel Anchor Suncor CQR Danforth Bruce grapnel plow swivel

Just one more silly add or there is something I don't know about Stainless steel versus high grade steel?

Regards

Paulo
PCP is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 14 Old 09-08-2011
Senior Member
 
tommays's Avatar
 
Join Date: Sep 2008
Posts: 4,296
Thanks: 1
Thanked 30 Times in 30 Posts
Rep Power: 7
 





I am just a humble backyard SS mixer repiar hack and Bicycle frame builder BUT all one would need to do is increase the metal thickness and hence overall weight in key areas to get a MUCH stronger unit




I fillet braze Columbus nivacrom bicycle tubing together and while some might thing brazing is to weak for such a strong steel you just need to use the correct method to make a large enough fillet and the tube will fail before the brazing

1970 Cal 29 Sea Fever

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

1981 J24 Tangent 2930
Tommays
Northport NY


If a dirty bottom slows you down what do you think it does to your boat
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
tommays is offline  
Quote Quick Reply Share with Facebook
post #3 of 14 Old 09-08-2011
Senior Member
 
CaptainForce's Avatar
 
Join Date: Jan 2006
Location: living aboard since 1972
Posts: 1,715
Thanks: 0
Thanked 12 Times in 12 Posts
Rep Power: 10
 
They're as beautiful as those hood ornaments on classic cars and too pretty to dip in the mud! I can't imagine that people are buying them because of their function,- they are "bling". Take care and joy, Aythya crew
CaptainForce is offline  
Quote Quick Reply Share with Facebook
post #4 of 14 Old 09-08-2011
Wandering Aimlessly
 
PBzeer's Avatar
 
Join Date: Nov 2002
Location: Cruising
Posts: 21,256
Thanks: 0
Thanked 94 Times in 91 Posts
Rep Power: 15
     
Gotta agree with CaptainForce on this one. Even if SS were stronger, I can't think of any time I've worried about my anchor failing, only whether I set it well.

John
Ontario 32 - Aria

Free, is the heart, that lives not, in fear.
Full, is the spirit, that thinks not, of falling.
True, is the soul, that hesitates not, to give.
Alive, is the one, that believes, in love.
JCP


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
- Website & Blog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
PBzeer is offline  
Quote Quick Reply Share with Facebook
post #5 of 14 Old 09-08-2011
Senior Member
 
RichH's Avatar
 
Join Date: Jul 2000
Location: Pennsylvania
Posts: 3,565
Thanks: 25
Thanked 167 Times in 156 Posts
Rep Power: 16
 
300 series stainless steel is indeed 'weaker' than an equivalent plain high strength steel.
Stainless steel has the same tensile properties as a high strength steel BUT is more subject to 'fatigue failure'. 300 series Stainless (90,000 psi tensile) has an 'endurance limit' of only 30,000 psi for cyclical stress applications. Cyclical stress is loading/unloading and if the stress level go much above that endurance limit, the material 'cold works' forms micro cracks and rapidly fatigues. Usually 300 series stainless can only withstand ~1 million load cycles above 30000 psi ... then falls apart!!!!!

Once the micro-cracks begin to form, & water enters the cracks and you then have an additional failure mode: crevice corrosion. Fatigue Failure + Crevice corrosion failure = catastrophe.

So, is stainless steel a good material for anchors? ... absolutely NOT!
Is stainless steel a good material for sailboat rigging? ... absolutely NOT! and thats why you have to replace your rigging so damn often.
RichH is offline  
Quote Quick Reply Share with Facebook
post #6 of 14 Old 09-08-2011
Senior Member
 
Join Date: Oct 2009
Location: Gloucester, MA
Posts: 586
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 6
 
It all depends what grades you are comparing. They say that their anchors are made of 316 which is good for corrosion but not super strong. If they compare to a low grade cast steel, the yield strength will be higher. However, if you compare to a high strength steel like that used in several of the modern anchors, 316 is very weak. There are much stronger types of stainless than this out there but I don't know of any that is used for anchors.

If you want to compare yield strength or tensile strength only, you can easily find information on many different types of steel online. There is an incredibly wide range depending on the steel.
klem is offline  
Quote Quick Reply Share with Facebook
post #7 of 14 Old 09-10-2011
Senior Member
 
Join Date: Sep 2010
Posts: 249
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 6
 
I don't think stainless steel is any weaker than normal steel. If anything it is stronger.

Someone mentioned a load cycle limit of 1,000,000 cycles over the fatigue limit (typically 1/2 of yield strength for steel). The fatigue limit is the point where stress cycles below that point do not cause failure of the material ever. Steel is one of the few materials that has a fatigue limit. The limit for Aluminum is like zero (it always fatigues). No anchor should be approaching 1/2 of the yield strength of the material on a regular basis.

I don't see how yield strength or the fatigue limit would be an issue for an anchor. But having a grade of stainless steel that does not hold up in saltwater would be kind of a waste of money. Also, your chain and all the parts that are electrically connected to the anchor must also be made out of stainless steel else the stainless will rapidly increase the rate of corrosion of the non stainless steel parts.

Last edited by steel; 09-10-2011 at 01:29 AM.
steel is offline  
Quote Quick Reply Share with Facebook
post #8 of 14 Old 09-10-2011 Thread Starter
PCP
Senior Member
 
PCP's Avatar
 
Join Date: Dec 2004
Location: Portugal, West Coast
Posts: 16,214
Thanks: 21
Thanked 105 Times in 88 Posts
Rep Power: 11
 
Thanks to all.

It seems that there is not a problem with stainless steel anchors but I would have to have also a stainless steel chain. I have looked at the prices of one of the best performance/price anchors, the Kobra II:

The 16kg stainless steel Kobra costs 1298.65. The Galvanized Steel 16kg Kobra costs 138.14


Plastimo Kobra Anchor Stainless Steel | GulfStreamShop.com

Plastimo Kobra Anchor Galvanised Steel | GulfStreamShop.com

I knew that the Stainless steel one was more expensive but I had no idea that would cost almost 10 times more

Regards

Paulo
PCP is offline  
Quote Quick Reply Share with Facebook
post #9 of 14 Old 09-10-2011
Senior Member
 
skygazer's Avatar
 
Join Date: Sep 2011
Location: western Maine
Posts: 394
Thanks: 2
Thanked 5 Times in 5 Posts
Rep Power: 5
 
Quote:
Originally Posted by RichH View Post
300 series stainless steel is indeed 'weaker' than an equivalent plain high strength steel.
Usually 300 series stainless can only withstand ~1 million load cycles above 30000 psi ... then falls apart!!!!!

Once the micro-cracks begin to form, & water enters the cracks and you then have an additional failure mode: crevice corrosion. Fatigue Failure + Crevice corrosion failure = catastrophe.

So, is stainless steel a good material for anchors? ... absolutely NOT!
Is stainless steel a good material for sailboat rigging? ... absolutely NOT! and thats why you have to replace your rigging so damn often.
So, if I use a stainless anchor I should become concerned after about my 500,000th storm while anchored in an exposed location...................... ?
skygazer is offline  
Quote Quick Reply Share with Facebook
post #10 of 14 Old 09-11-2011
Senior Member
 
Join Date: Oct 2009
Location: Gloucester, MA
Posts: 586
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 6
 
If you look at an SN curve for steel, you will see that there is a given stress level below which an infinite number of cycles are possible and at higher stress levels, fewer and fewer cycles are possible. Ideally, the anchor will be designed so that the stress never exceeds the value for infinite life.

Comments like stainless is as strong as regular steel are not fair because there are too many grades. There are strong stainless steels like 17-4 and there are weak ones (316 being relatively weak). The same thing is true for steel with steels like 4140 being pretty strong and something like 1018 being relatively weak. How the material is heat treated also makes a huge difference. A materials engineer could go into much greater detail but the gist of it is that the stainless anchors are not made out of very strong material.
klem is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Stainless steel anchors AdamLein Gear & Maintenance 31 07-07-2009 06:08 PM
Stainless Steel... merttan Gear & Maintenance 14 04-12-2008 07:59 PM
Stainless anchors Craig Smith Gear & Maintenance 2 02-19-2007 10:15 AM
Combination stainless steel chain/ galvanized steel anchor Grigrigrigoris Gear & Maintenance 11 07-03-2005 03:46 PM
Spade Anchors Aluminum vs Steel thomsonjd Gear & Maintenance 1 12-31-2001 12:54 PM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome