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 > Replacing lead Keel bolts
 Not a Member? 


Thread: Replacing lead Keel bolts 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)
10-20-2012 10:24 AM
eherlihy
Re: Replacing lead Keel bolts

Quote:
Originally Posted by Brewgyver View Post
Eherlihy, I'm wondering if the root cause of the damage to those bolts is more stretching than corrosion? Anybody?
I can't speak to that, as I did not build the boat, and she was not mine when those pictures were taken.

I believe that what you are looking at is simple crevice corrosion. Those lines in the metal are simply the way that the corrosion traveled through the steel.
10-20-2012 02:18 AM
Stumble
Re: Replacing lead Keel bolts

Quote:
Originally Posted by Brewgyver View Post
Eherlihy, I'm wondering if the root cause of the damage to those bolts is more stretching than corrosion? Anybody?
It's a pretty easy check, just try and thread a nut down on the existing threads. But I don't see anything that looks like elongation. The pictures are pretty typical of general corrosion eating away at the bolts.
10-20-2012 02:17 AM
Stumble
Re: Replacing lead Keel bolts

Quote:
Originally Posted by cousineddy View Post
The 13700 holding capacity is per bolt. There are 6 bolts. Total holding capacity is 82200 lbs. That oughtta do er.
As I said above the 5:1 safety margin is per bolt. Assuming each bolt alone is holding the entire keel. The justification for this is that when the boat is rolled onto it's side, and being slapped by waves, there is no telling how unequal the forces are going to be applied. It very well may be that just the front bolt will have to briefly hold the entire weight of the keel, plus it's momentum on the boat, even if everything else is in good shape.
10-19-2012 06:11 PM
Brewgyver
Re: Replacing lead Keel bolts

Eherlihy, I'm wondering if the root cause of the damage to those bolts is more stretching than corrosion? Anybody?
10-19-2012 05:31 PM
cousineddy
Re: Replacing lead Keel bolts

Titanium is the best choice. It will never corrode in salt water. The only substance that can penetrate its protective oxide coating is a strong acid, like hydroflouric.

Silicon Bronze is more corrossion resistant than stainless, both 18-8 and 316 in salt water. No advantage in fresh water. Just gotta make sure you get good quality bolts. We tested silicon bronze against brass at work for a non-magnetic application. They were only half as strong as they were supposed to be. So, we abandoned them.
10-19-2012 05:08 PM
Plumbean
Re: Replacing lead Keel bolts

Quote:
Originally Posted by casey1999 View Post
My lead keel attachment is just like yours (windows). My original keel bolts are stainless steel and appear ok (34 years old), but maybe one day I will need to replace.

Would silicon bronze be preferred over stainless? Titanium is also becoming available at a resonable price, any thoughts?

What is your boat make?
Regards
Casey: Looks the same because it is the same boat! Aquafibre built S&S34. Someone had encapsulated the bolt heads in the bilge and they had corroded due to the lack of oxygen. On some there were only 3 full turns of the threads left on the bolt in the bilge. The rest of the bolt looked fine, just the part in the bilge was corroded. Silicon Bronze is more expensive but won't corrode like stainless. I only wanted to do this job once, so decided to spring for the silicon bronze.
10-19-2012 05:02 PM
cousineddy
Re: Replacing lead Keel bolts

The 13700 holding capacity is per bolt. There are 6 bolts. Total holding capacity is 82200 lbs. That oughtta do er.
10-19-2012 04:35 PM
Stumble
Re: Replacing lead Keel bolts

Quote:
Originally Posted by cousineddy View Post
Actually, that 5 times safety factor works for the 1/2 hanger bolts. 1400 x 5 = 7000 per bolt, which is about what i calculated was required for a 1x safety factor. So, having a 13700 lb holding capacity gives me an over all safety factor of 2x. I get a warm fuzzy with that margin.
I think you misunderstand. Each bolt assembly however anchored should have at least a 5 times safety margin.

Your assembly's week point is the attachment mechanism. So you have to design to that. If the max load the keel will generate is 7,000lbs, then you need an attachment mechanism, and bolts rated to 35,000lbs. Your design is woefully undersized.
10-19-2012 03:26 PM
casey1999
Re: Replacing lead Keel bolts

Quote:
Originally Posted by Plumbean View Post
While probably most boats are made with "j" bolts for their keel bolts, there are plenty that used the pocket method, mine included. Here is what they looked like when we dropped the keel and replaced them all with silicon bronze.

My lead keel attachment is just like yours (windows). My original keel bolts are stainless steel and appear ok (34 years old), but maybe one day I will need to replace.

Would silicon bronze be preferred over stainless? Titanium is also becoming available at a resonable price, any thoughts?

What is your boat make?
Regards
10-17-2012 06:04 PM
cousineddy
Re: Replacing lead Keel bolts

Actually, that 5 times safety factor works for the 1/2 hanger bolts. 1400 x 5 = 7000 per bolt, which is about what i calculated was required for a 1x safety factor. So, having a 13700 lb holding capacity gives me an over all safety factor of 2x. I get a warm fuzzy with that margin.
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 11:48 PM.

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.