Tether overload protection - Page 3 - SailNet Community
 39Likes
Reply
 
LinkBack Thread Tools
post #21 of 29 Old 04-26-2019
Senior Member
 
Join Date: Feb 2002
Location: Jackson WY
Posts: 2,212
Thanks: 45
Thanked 85 Times in 84 Posts
Rep Power: 19
 
Re: Tether overload protection

Quote:
Originally Posted by SteffanieS View Post
I suspect they got tired of all us newbies getting seasick.
Either that or sailing outside of the gate is serious business. Sailing inside the gate is serious business.
MarkofSeaLife and SteffanieS like this.

Jordan
West Wight Potter 14 "Lemon Drop"
Oceanside CA
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.
jephotog is online now  
Sponsored Links
Advertisement
 
post #22 of 29 Old 04-26-2019
Administrator
 
Jeff_H's Avatar
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 8,914
Thanks: 44
Thanked 444 Times in 374 Posts
Rep Power: 10
     
Re: Tether overload protection

Quote:
Originally Posted by SteffanieS View Post
After watching a YouTube video on the testing of tethers, I'm fairly certain that if I fall off the boat attached to a tether, I'd better have a sharp rigging knife at the ready so I can cut myself free. It looked like a sure-fire way to drown. I'm assuming the only way a tether would save my life is to keep me on the boat in the first place. Barring that, the skipper had better be really good at stopping the boat on a dime or I'll drown at any boat speed above 2 knots.

On my own boat, I need to rig the jack lines so I won't go overboard. If I'm single-handed, the skipper will be me.

I'm going to order that $100 tether now...
In terms of carrying a sharp knife, modern tethers have a snap shackle at the chest ring that you can pull if you need to get free of the tether in a hurry. The sharp knife thing is actually pretty much of an urban legend since I can't imagine anyone actually being able to get their hands on a knife, open it, find and cut the tether while being dragged at several knots face first through the water.

The current thinking is that at any speed at all, the chest ring attachment of the tether will place the person being towed in a pretty dangerous position that is as likely to drown them as save them. There are some experimental harness set-ups that have a a back ring as well as a chest ring. These use a tether that has a snap shackle at the chest ring with a length of tether that runs to the back ring. If the person in the water feels like they are being drown by being towed, they can blow the chest ring and be towed from their back instead, which is safer in terms of drowning. But that set up only works with a crew on board to retrieve you since you can no longer reach the tether to pull yourself back aboard.

Having tried to pull myself aboard from the water in wet clothing, my belief is that if I were hanging from a tether with my body completely over the side, I have about a 50-50 chance of pulling myself aboard if I wasn't injured going over the side and almost no chance if i were injured. For me as a single-hander, the tethers and jacklines are solely to keep me on board and ideally inside the toerails from my waist up.

Jeff
SteffanieS likes this.


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  
post #23 of 29 Old 04-26-2019
Senior Member
 
PhilCarlson's Avatar
 
Join Date: Dec 2013
Location: Tampa FL
Posts: 476
Thanks: 7
Thanked 39 Times in 39 Posts
Rep Power: 7
 
Dock
Re: Tether overload protection

Quote:
Originally Posted by Jeff_H View Post
...modern tethers have a snap shackle at the chest ring that you can pull if you need to get free of the tether in a hurry.
I'm curious about the use of a snap shackle in this application, having seen a few release at inopportune times in other applications. It would never even cross my mind to trust a snap shackle as a personal anchor. Seems like it would be the weak point in the system.

Thoughts?

Last edited by PhilCarlson; 04-26-2019 at 11:12 AM.
PhilCarlson is offline  
 
post #24 of 29 Old 04-26-2019
Senior Member
 
Join Date: Aug 2010
Location: The Bahamas
Posts: 4,143
Thanks: 3
Thanked 153 Times in 151 Posts
Rep Power: 10
 
I dont disagree. I would expect a one handed safety latch.
Mine has snap shackle
RegisteredUser is online now  
post #25 of 29 Old 04-26-2019 Thread Starter
Junior Member
 
Join Date: Jul 2018
Posts: 18
Thanks: 4
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: Tether overload protection

Quote:
Originally Posted by Jeff_H View Post
In terms of carrying a sharp knife, modern tethers have a snap shackle at the chest ring that you can pull if you need to get free of the tether in a hurry. The sharp knife thing is actually pretty much of an urban legend since I can't imagine anyone actually being able to get their hands on a knife, open it, find and cut the tether while being dragged at several knots face first through the water.
Yeah, that didn't exactly sound feasible to me either. However, there are some tethers that attach to the harness by a loop, no shackle. There would be no release in this case. You can buy a gadget for slicing through the tether in a pinch, but I'm not sure it's much better than a knife.

Quote:
For me as a single-hander, the tethers and jacklines are solely to keep me on board and ideally inside the toerails from my waist up.

Jeff
That is exactly my plan on my own boat.
SteffanieS is offline  
post #26 of 29 Old 04-27-2019
TQA
Bombay Explorer 44
 
TQA's Avatar
 
Join Date: Apr 2009
Posts: 3,619
Thanks: 0
Thanked 132 Times in 128 Posts
Rep Power: 12
 
Re: Tether overload protection

I flew hang gliders intensively for 10 years and then at odd times for the next twenty years.

After 30 years I decided to stop flying and cut up my harness. All the webbing straps showed signs of slight bleaching by the sun.

But all seemed still sound.
TQA is offline  
post #27 of 29 Old 04-27-2019
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 3,719
Thanks: 4
Thanked 131 Times in 129 Posts
Rep Power: 12
 
Re: Tether overload protection

ISO and World Sailing standards do not specify a quick-release at the harness end. Personally I would always have some manner of release; I've gotten on the wrong side of rigging numerous times and it is handy if you can just clip back around.

Whether a quick release is better has been debated. A singlehander will point out that spin shackles occasionally come loose, and they don't believe release is likely to save them. On the other hand, sailor have been trapped by tethers that didn't release; the Windnutz accident was high profile.

If you do have a snap shackle, remember that if you clip the unused tether to the harness you have defeated the quick release function (after release you will be held to the harness by the other leg--one of the Windnutz sailors made this mistake); you need to have a parking loop on the ether or clip it in to the snap shackle eye... if it is large enough, which most are not.

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 offline  
post #28 of 29 Old 04-28-2019
Junior Member
 
Join Date: Jul 2018
Location: SF Bay Area
Posts: 19
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: Tether overload protection

Having a cutting tool you can actually use when being waterboarded is always wise (lines under tension are also easy to cut). If you wear an inflatable PFD, the "rescue hook" style cutters may be both more effective and safer for the PFD. Still, I'd prefer a proper quick-release mechanism and I'm not convinced snap shackles are actually designed for that. In the WingNuts case, I think only one of the crew was able to use the snap-shackle release as intended.

Interesting reading is the PS article on tethers from back in 2011, which also mentions that it took 34-38 lbs of force to open the shackles under load: https://www.practical-sailor.com/iss...r_10574-1.html

As to improvised tethers, this is an area where climbers may better understand the forces involved. Fall factors are counted by the ratio of the fall distance to the available rope. A factor of 1 (you are at the anchor and fall the full length of the tether) represents a significant impact. A factor 2 fall means you climbed above the anchor and so fell twice the length of the tether. In drop tests, a factor 2 fall is sufficient to break Dyneema slings. (Humans are squishier, so more likely to break than the sling.)

Hopefully a boat presents less opportunity for such a fall; a more "gentle" slide under the lifelines will generate less force, and a connection to the jacklines means the length of the jacklines is also involved in absorbing energy. Still, the forces involved with "sudden stops" shouldn't be underestimated. This is why via ferrata gear includes shock absorbers; via ferrata falls can easily exceed factor 2. The takeaway? Try not to put yourself in positions where you could take a hard fall on a tether.
requiem is offline  
post #29 of 29 Old 04-28-2019
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 3,719
Thanks: 4
Thanked 131 Times in 129 Posts
Rep Power: 12
 
Re: Tether overload protection

Quote:
Originally Posted by requiem View Post
... Fall factors are counted by the ratio of the fall distance to the available rope. A factor of 1 (you are at the anchor and fall the full length of the tether) represents a significant impact. A factor 2 fall means you climbed above the anchor and so fell twice the length of the tether. In drop tests, a factor 2 fall is sufficient to break Dyneema slings. (Humans are squishier, so more likely to break than the sling.)

Hopefully a boat presents less opportunity for such a fall; a more "gentle" slide under the lifelines will generate less force, and a connection to the jacklines means the length of the jacklines is also involved in absorbing energy. Still, the forces involved with "sudden stops" shouldn't be underestimated. This is why via ferrata gear includes shock absorbers; via ferrata falls can easily exceed factor 2. The takeaway? Try not to put yourself in positions where you could take a hard fall on a tether.
The ISO and World Sailing standard includes a drop that is fall factor 1 but with slightly greater mass. About factor 1.3.

A fall factor 1.3 only means you've been thrown across the cockpit at 7 knots with a wave following you. It does NOT require an actual fall, only equivalent energy.

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 offline  
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
Can you overload a 12 volt battery? Bruce3966 General Discussion (sailing related) 58 09-15-2015 08:44 AM
West Marine Combine/Overload module??? csharp56 Electrical Systems 1 07-29-2013 06:27 AM
Don't watch these videos unless you are suffering from election overload disorder and knothead General Discussion (sailing related) 1 11-01-2008 09:56 PM
Toddler PFD-harness/ tether h20ski General Discussion (sailing related) 11 04-18-2006 02:59 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