SailNet Community - Reply to Topic

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance > Chain plate help
 Not a Member? 


Thread: Chain plate help Reply to Thread
Title:
  

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

Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:
 

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:

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.



Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Topic Review (Newest First)
12-20-2010 12:46 PM
sailingdog Even if the welds are made with the proper welding wire stock, the issue of corrosion at the welds still exists. Also, the suggestion of replacing the steel with PVC does very little good for the OP who is replacing CHAINPLATES, which are very high load items. PVC is not very strong.

Quote:
Originally Posted by CaptainJesse View Post
Not always is stainless welded with the exact same material as the base metal. Close to the same material is not good enough. Polishing the welds can deter external corrosion but not internal and as we know some steel boats rust from the inside out. Aluminum and stainless steel fuel, water and holding tanks rust and corrode from the inside out. Most commonly this rust and corrosion appears at the welded joints and especially where these tanks come in contact with foam insulation or rest on their mounts. In your customer's situation I would consider not just these conditions but also the dissimilar metals and especially if they are in contact with the galvanized mild steel framework. On my water maker I replaced every item I could with PVC, even making the filter chambers from 4" PVC pipe with end caps and reducers thus eliminating 99% of the corrosion problems with no adverse effects to the system.
12-20-2010 02:27 AM
CaptainJesse
Do away with rust and corrosion

Quote:
Originally Posted by GaryHLucas View Post
Interesting little story about stainless steels. This week we got back a wastewater RO filtration unit from a customer. All the stainless on this unit was 316. The sch 40 piping was welded and not subsequently finished in any way. It was all quite corroded at all the welds. The filter canister was a bead blasted finish, and eaten completely through in several places! The high pressure Can pump had an electropolish finish, and was still bright and shiny everywhere. Interestingly, the hot dip galvanized frame still looked great! I don't know what they were processing, but it sure raised hell with stainless steel.

Gary H. Lucas
Not always is stainless welded with the exact same material as the base metal. Close to the same material is not good enough. Polishing the welds can deter external corrosion but not internal and as we know some steel boats rust from the inside out. Aluminum and stainless steel fuel, water and holding tanks rust and corrode from the inside out. Most commonly this rust and corrosion appears at the welded joints and especially where these tanks come in contact with foam insulation or rest on their mounts. In your customer's situation I would consider not just these conditions but also the dissimilar metals and especially if they are in contact with the galvanized mild steel framework. On my water maker I replaced every item I could with PVC, even making the filter chambers from 4" PVC pipe with end caps and reducers thus eliminating 99% of the corrosion problems with no adverse effects to the system.
12-19-2010 10:06 PM
sailingdog
Quote:
Originally Posted by GaryHLucas View Post
Interesting little story about stainless steels. This week we got back a wastewater RO filtration unit from a customer. All the stainless on this unit was 316. The sch 40 piping was welded and not subsequently finished in any way. It was all quite corroded at all the welds. The filter canister was a bead blasted finish, and eaten completely through in several places! The high pressure Can pump had an electropolish finish, and was still bright and shiny everywhere. Interestingly, the hot dip galvanized frame still looked great! I don't know what they were processing, but it sure raised hell with stainless steel.

Gary H. Lucas
Not surprised the bead blasted portion and welds got eaten up. Not surprised the electropolished stuff was in good shape. The irregular surface of the bead blasted areas encourage crevice corrosion and that's why it got eaten away so badly. IIRC, the welds tend to be more prone to corrosion because the alloy composition changes due to the high temperatures of the welding process, since the various components of the stainless steel alloy have different melting points. The increased corrosion can be reduced by using low carbon versions of the alloy, 316L, rather than 316.
12-19-2010 08:13 PM
GaryHLucas Interesting little story about stainless steels. This week we got back a wastewater RO filtration unit from a customer. All the stainless on this unit was 316. The sch 40 piping was welded and not subsequently finished in any way. It was all quite corroded at all the welds. The filter canister was a bead blasted finish, and eaten completely through in several places! The high pressure Can pump had an electropolish finish, and was still bright and shiny everywhere. Interestingly, the hot dip galvanized frame still looked great! I don't know what they were processing, but it sure raised hell with stainless steel.

Gary H. Lucas
12-18-2010 11:33 AM
CaptainJesse You have just joined a large group of concerned sailors who are in the same situation. Early versions of the Island Packet yachts were plagued with corrosion problems in their chain plates as was a lot of the older Hinkleys. Many manufacturers use this method of fiberglassing the chain plate weldment into the laminate of the hull. Contact the owners association of these boats. I am sure there will be plenty of interesting solutions to chose from. I prefer being able to inspect them visually, either through external mounting to the hull or bulkhead mounted chain plates. Also consider hull liner/tie rod installations, ie: Beneteau, Catalina, Hunter and other manufacturers using interior grid/liner construction. Consider and get quotes for the repair before making an offer. Your surveyor will advise you to the extent these repairs may take.
12-17-2010 10:48 PM
RichH If the plates are simple 'bar' and have no welding alterations, etc. then plain 316 will perform to the same level as 316L.

wkeenan - Just imitate the same shape and size of the OEM plates just change the materials and surface finish. If you have had 'failure' then of course you can increase the 'cross section' of the OEM plates. Dont totally reinvent the wheel, just make the old wheel 'better' - small steps of improvement.
12-17-2010 10:16 PM
wkeenan78 So stainless it is, 316L sounds to be the bees knees for this application. Can I also purchase 316L hardware? What size hardware? What length should I make the chainplates? What size stainless stock do I use to make them out of? How far apart do I drill the mounting holes? Can I use aluminum for backing plates or should I use stainless for that too?

Mabey I need to go buy a book on rigging... I still cant figure out how much tension to adjust the shrouds to either. I'm not a racer, just a cruiser. Thank you so much for all your help. Any answers you can give are much appreciated!
12-17-2010 09:56 PM
sailingdog Rich—

316L... agree with the electropolishing though.
12-17-2010 09:09 PM
RichH Aluminum7075 T6 in contact with halides (NaCl > 0.5% wt.) similar to seawater has a very low nominal "Fatigue Endurance Limit" .... about 15,000 psi. Chainplates and other components that are subject to repetitive cyclic stress loads will typically fail in fatigue/brittle failure mode and not in 'ductile failure'.

The nominal Fatigue Endurance Limit FEL for 7075 T6, depending on post treatment, can be as high as 25-30,000 psi; but, when in contact with chlorides, etc. can be 1/2 that value 12-15ksi. Assuming a design Safety Factor for this boat at FS=3 and a UTS of 60ksi, UYS of 53ksi, FEL of 15ksi ... ... ... ... I'd be selecting stainless 316 for the plates and would be mechanical mirror polishing (followed by electropolishing if possible) the 316 to retard both fatigue and crevice corrosion potential and would be selecting 30ksi as the FEL for that material.
12-17-2010 03:26 PM
sailingdog IMHO, you'd be better off with 316L stainless steel for chainplates. First, IIRC aluminum is far less fatigue resistant. Second, aluminum is less noble and you'd probably be using stainless steel fasteners with them. Using stainless steel and aluminum together with fairly large stainless steel fasteners is generally a bad idea, since the galvanic corrosion issues are far more likely because of the size of the fasteners.

Quote:
Originally Posted by wkeenan78 View Post
I have a Starratt & Jenks 45' sloop with the chainplates fiberglassed into the hull. I dont trust them and will be fabricating and installing external ones. I have found a few pieces of stainless on the boat that had very small rust lines on them, when I tested them with a lever, they snapped very easy on the line. I want to make new ones out of 7075 T6 Aluminum alloy .75" X 2.5" flat bar. The 7075 T6 alloy is not your average aluminum with a yield strength of over 53,000 lbs. Thoughts and input would be greatly helpful.
This thread has more than 10 replies. Click here to review the whole thread.

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


All times are GMT -4. The time now is 07:55 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.