Attachment method for Vang - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 18 Old 11-17-2007 Thread Starter
STARBOARD!!
 
KeelHaulin's Avatar
 
Join Date: Mar 2006
Posts: 1,662
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 11
   
Attachment method for Vang

I'm going to add a standard (non-supportive) vang soon and I was wondering what the best way to attach the block at the mast would be. We have an un-used bail on the boom 1/3 of the way back from the gooseneck that will work for the vang. At the mast I could either use a padeye or a pole ring. The pole ring looks stronger; we had a padeye rip out in a mildly uncontrolled gybe (preventers are going on soon also).

I was considering the Ronstan RF41 if it has the right radius to fit the mast.

http://shop.sailnet.com/product_info...oducts_id/4964
KeelHaulin is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 18 Old 11-17-2007
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,534
Thanks: 104
Thanked 310 Times in 300 Posts
Rep Power: 10
     
There can be a tremendous load on that fitting under heavy going... It will be difficult to make either of those types of fittings attached sufficiently strong.

We had a fitting that bolted to a long slug that slid into the sail track groove and locked in place. It was identical to the gooseneck pivot, so the rotation of the boom and the vang fitting matched perfectly.

This was on a 24 foot day racer.





Hopefully you can make sense of this... If the attachment bolts (which thread through the long slug) are long enough that they will pass through holes drilled in the back of the sail track as shown, the fitting will never move.

I believe this was a commercially available fitting, but we have had a machinist make one of these as well.

Last edited by Faster; 11-17-2007 at 01:24 AM.
Faster is offline  
Quote Quick Reply Share with Facebook
post #3 of 18 Old 11-17-2007
Here .. Pull this
 
Join Date: Jan 2007
Posts: 2,031
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
How big is your boat/sail ???
Sailormann is offline  
Quote Quick Reply Share with Facebook
post #4 of 18 Old 11-17-2007 Thread Starter
STARBOARD!!
 
KeelHaulin's Avatar
 
Join Date: Mar 2006
Posts: 1,662
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 11
   
The sail is 350 sq-ft, a bit on the small side for a 41' boat. We do get into heavy wind on SF Bay. Harken Compu-Spec gives blocks rated SWL of 1500 lbs; break strength of 3050 lbs. Is something wrong with this load spec?

Last edited by KeelHaulin; 11-17-2007 at 01:44 AM.
KeelHaulin is offline  
Quote Quick Reply Share with Facebook
post #5 of 18 Old 11-17-2007
Telstar 28
 
sailingdog's Avatar
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 15 Times in 12 Posts
Rep Power: 14
         
Given that the vang attaches mid-boom... you might want to go a bit stronger on the blocks... and I'd have to agree that a simple padeye or pole ring isn't going to be sufficiently strong. You need a boom bail or something similar that is through bolted.

Sailingdog

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

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
sailingdog is offline  
Quote Quick Reply Share with Facebook
post #6 of 18 Old 11-17-2007
Senior Member
 
NOLAsailing's Avatar
 
Join Date: Sep 2006
Location: Mandeville, LA
Posts: 504
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
Quote:
We had a fitting that bolted to a long slug that slid into the sail track groove and locked in place. It was identical to the gooseneck pivot, so the rotation of the boom and the vang fitting matched perfectly.
That looks like the fitting for a Boomkicker, which supports the boom like a rigid vang and is used in conjunction with a soft vang. The loads are mostly compressive (see photo for fitting).



For a soft vang, I don't think I trust that fitting. On my boat I have a robust plate held in place with 8 or 10 rivets. The vang can really load up, don't undersize this fitting.


-Jason

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
NOLAsailing is offline  
Quote Quick Reply Share with Facebook
post #7 of 18 Old 11-17-2007
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,534
Thanks: 104
Thanked 310 Times in 300 Posts
Rep Power: 10
     
Quote:
Originally Posted by NOLAsailing View Post
That looks like the fitting for a Boomkicker, which supports the boom like a rigid vang and is used in conjunction with a soft vang. The loads are mostly compressive (see photo for fitting).



For a soft vang, I don't think I trust that fitting. On my boat I have a robust plate held in place with 8 or 10 rivets. The vang can really load up, don't undersize this fitting.

Nola - the attachment method is the same as I described above, but there is an essential difference in the outer fitting. As a gooseneck/vang attachment it is important that the fitting conforms to the mast shape in such a way as to compress the edges of the sail track against the inner slug so as to prevent the sail track from "peeling" open under load. Without those "shoulders" to trap the extrusion, you're right, under tension it may be subject to failure if sufficient load was applied.

In my experience on 40 footers these types of fitting are often welded onto the mast to avoid issues of fastener failure. But our old 24 foot (SA/D =29 - fairly powered up) racer used the fitting described above for both gooseneck and vang. Some early models that used a through-bolted bail at the partners for the vang suffered mast failures.
Faster is offline  
Quote Quick Reply Share with Facebook
post #8 of 18 Old 11-19-2007 Thread Starter
STARBOARD!!
 
KeelHaulin's Avatar
 
Join Date: Mar 2006
Posts: 1,662
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 11
   
So the greater issue is fasteners stripping out? That makes sense; but unfortunately I don't have a mast that has an extruded track in it; so that type of fitting is not going to work. Looks like I will either have to beef up the holding ability of the pole ring or design something that will have enough holding power.

Thanks for the help...
KeelHaulin is offline  
Quote Quick Reply Share with Facebook
post #9 of 18 Old 11-19-2007
.
 
Join Date: Nov 2006
Posts: 10,851
Thanks: 0
Thanked 5 Times in 2 Posts
Rep Power: 13
         
Keel,

For a bot your size, I think you should invest some money and have a metal shop fabricate something like this for you.

Its is simple a Plate is bent to conform to your mast radius, then a hinge is welded above and bellow and tube with the fitting is held by a bolt.

Its very simple. Look at mine. You then attach with bots or rivets.




Last edited by Giulietta; 11-19-2007 at 01:39 PM.
Giulietta is offline  
Quote Quick Reply Share with Facebook
post #10 of 18 Old 11-19-2007
.
 
Join Date: Nov 2006
Posts: 10,851
Thanks: 0
Thanked 5 Times in 2 Posts
Rep Power: 13
         
I made also this drawing for you.

Giulietta 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
Radius Chine Plywood method? Cyberjag General Discussion (sailing related) 5 01-20-2008 11:20 PM
Proper Line Cleating Method Sabreman Seamanship & Navigation 27 09-07-2007 06:14 PM
Prop strut attachment fairing aphil138 Gear & Maintenance 1 04-02-2007 09:10 AM
Coffee: Best/Simplest method pluscard General Discussion (sailing related) 7 07-04-2006 11:51 AM
Forestay Attachment jkolle Gear & Maintenance 1 06-16-2006 05:56 AM

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