Jack Lines - Page 4 - SailNet Community
 11Likes
Reply
 
LinkBack Thread Tools
post #31 of 38 Old 05-08-2019
Administrator
 
Jeff_H's Avatar
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 8,795
Thanks: 39
Thanked 432 Times in 362 Posts
Rep Power: 10
     
Re: Jack Lines

Quote:
Originally Posted by Jeff_H View Post
I would assume that you add an eye to the 1" webbing by having the eye professionally sown by a company who is certified to do that kind of structural sewing....
Jeff
Quote:
Originally Posted by pdqaltair View Post
Does this exist? In a practical sense, not really.

In a former life I manufactured climbing gear, and generally, we are talking self-certifications though ISO (6 sigma break testing program). That's it and many are not. Realistically, a sailmaker will do it. You will also need to source the correct webbing, which is a problem.

You are right that the Dyneema approach is probably best for DIYs. Fewer question marks and a solid finished product.
I don't know whether its true that companies that are certified to do that kind of structural sewing exists, but I see 'OSHA' certified safety harnesses and tethers and so I have always assumed that there are companies that are certified to do structural stitching. That said, I have no idea if that is actually the case.

Jeff


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
Jeff_H is online now  
Sponsored Links
Advertisement
 
post #32 of 38 Old 05-08-2019 Thread Starter
Senior Member
 
SanderO's Avatar
 
Join Date: Jul 2007
Location: Northport, NY
Posts: 3,670
Thanks: 2
Thanked 94 Times in 94 Posts
Rep Power: 13
 
Re: Jack Lines

With all due respect... I do not need a system designed to 5000# load... static or dynamic. This WAY more than the force of a 200# human be tossed my boat motion from a wave.

Stretch? I how much stretch will a 25' line loaded when a person is tossed by a wave? Another nonsense concept. Actually a little shock absorption is not a bad idea!

I will keep the vinyl coated wire jack lines as back up.... so I am not concerned about being with no jack lines.

pay attention... someone's life depends on it

Last edited by SanderO; 05-08-2019 at 05:46 PM.
SanderO is online now  
post #33 of 38 Old 05-08-2019
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 3,636
Thanks: 4
Thanked 127 Times in 125 Posts
Rep Power: 12
 
Re: Jack Lines

Quote:
Originally Posted by SanderO View Post
With all due respect... I do not need a system designed to 5000# load... static or dynamic. This WAY more than the force of a 200# human be tossed my boat motion from a wave.

Stretch? I how much stretch will a 25' line loaded when a person is tossed by a wave? Another nonsense concept. Actually a little shock absorption is not a bad idea!

I will keep the vinyl coated wire jack lines as back up.... so I am not concerned about being with no jack lines.
* Safety Factor. Your anchor chain has a safety factor. Your shrouds have a safety factor. For safety critical applications a 10:1 safety factor is common, depending on the materials.
* Wear.
* Dynamic forces. If you cannot calculate it or measure, then you guess, I assume.
* Humans HAVE broken tethers on boats. You can google this. That is the reason the standards were updated to include a drop test. People died. And they weren't 200-pound humans. Most recently a skinny guy died on one of the Clipper Race boats (CV30--google it) because his tether parted; I believe new standards will result, since a clip meeting the last standard failed.

You have declared disrespect for ANSI, ISO, OSHA, ISAF/WS, and UIAA. OK.

I don't always or even often use tethers. But I would not want to have safety gear that was unreliable. That's worse than none, if you have fooled yourself into believing that it is good.

Writing full-time since 2014
Author--Rigging Modern Anchors

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


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

"Keeping a Cruising Boat for Peanuts"
"Faster Cruising for the Coastal Sailor"
"Singlehanded Sailing for the Coastal Sailor"

Last edited by pdqaltair; 05-08-2019 at 07:32 PM.
pdqaltair is online now  
 
post #34 of 38 Old 05-08-2019 Thread Starter
Senior Member
 
SanderO's Avatar
 
Join Date: Jul 2007
Location: Northport, NY
Posts: 3,670
Thanks: 2
Thanked 94 Times in 94 Posts
Rep Power: 13
 
Re: Jack Lines

I have Lirakis harnesses and they are very robust.

I am not contemplating any offshore work in the foreseeable future. And I don't know whether I will do new jack lines or not... but for the use contemplated... 1" dacron will suffice.

Thank you for your concern!

pay attention... someone's life depends on it
SanderO is online now  
post #35 of 38 Old 05-08-2019
Senior Member
 
colemj's Avatar
 
Join Date: Jul 2003
Location: On the boat cruising
Posts: 2,863
Thanks: 4
Thanked 114 Times in 108 Posts
Rep Power: 17
 
Re: Jack Lines

Quote:
Originally Posted by SanderO View Post
Stretch? I how much stretch will a 25' line loaded when a person is tossed by a wave? Another nonsense concept. Actually a little shock absorption is not a bad idea!
Actually, stretch is one of the things I dislike about our current polyester webbing lines. When they are wet, they get very loose, and when they are in the sun, they get like guitar strings.

On our recent trip from Antigua to Georgia, I just rigged some old dyneema halyards as jacklines and liked that much better. I think I will be replacing the webbing with 1/4" dyneema in the future.

As for shock absorption, there will be enough of that just in the bowstring effect from the unsupported run, as well as the stretchy tether. In addition, one won't be coming up dead short on the jackline, they will also be sliding along it for some distance, which reduces the shock force. But personally, I think the less stretch in the static system the better - the dynamics will be providing the force reduction.

Mark
SanderO likes this.

Dolphin 460 Catamaran "Reach"

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

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
- Previous boat
colemj is offline  
post #36 of 38 Old 05-08-2019
Senior Member
 
Join Date: Aug 2010
Location: The Bahamas
Posts: 3,704
Thanks: 3
Thanked 139 Times in 137 Posts
Rep Power: 10
 
Sure.
Tether onto a mast..padeye or side rail and you arent asking how much 'give' that hardware allows.

Good discussion...but north is still north.
RegisteredUser is online now  
post #37 of 38 Old 05-08-2019
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 3,636
Thanks: 4
Thanked 127 Times in 125 Posts
Rep Power: 12
 
Re: Jack Lines

Quote:
Originally Posted by SanderO View Post
...Stretch? I how much stretch will a 25' line loaded when a person is tossed by a wave? Another nonsense concept. Actually a little shock absorption is not a bad ....
In testing, as much as 2 feet (PS Magazine). Or you could place a 25' section between two trees, without pretension, and step onto it. The static load will be on the order of 500 pounds and it will sag about 2 feet, depending on the product. Certainly body weight is reasonable. Try it. I have. Any slackliner or tight rope walker know of this. and look how many sailors, like ColeMj, have simply noticed it. Any engineer can check my math; it's high school physics and trig. Nothing complex in the static case.

Why belittle a concept you have not studied and have no personal knowledge of? You can test this for yourself.
SanderO likes this.

Writing full-time since 2014
Author--Rigging Modern Anchors

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


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

"Keeping a Cruising Boat for Peanuts"
"Faster Cruising for the Coastal Sailor"
"Singlehanded Sailing for the Coastal Sailor"
pdqaltair is online now  
post #38 of 38 Old 05-08-2019
Senior Member
 
Join Date: Aug 2010
Location: The Bahamas
Posts: 3,704
Thanks: 3
Thanked 139 Times in 137 Posts
Rep Power: 10
 
How bout dem Braves?

Springs wound tight....
RegisteredUser is online now  
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











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
Small Boat Jack Lines and Safety Tethers sparrow16 General Discussion (sailing related) 2 04-24-2013 10:34 AM
Jack lines and tethers rjcaudle Seamanship & Navigation 61 12-29-2011 06:17 AM
Jack lines flyingwelshman Gear & Maintenance 4 06-26-2011 01:13 PM
Kids & Jack Lines? tmckinn Learning to Sail 9 06-28-2006 07:50 PM
Question bout Jack Lines mmccoy Gear & Maintenance 6 12-09-2004 03:09 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