There is a lot more engineering in this than folks realize. As a 30-year engineer
, 25-year sailor, and 30-year rock and ice climber that has logged more air time than most would like to consider (thousands of falls), I think I have a few thoughts of value. Fortunatly, I've posted most of this elsewhere so I don't need to retype it.
Yes, I agree there is money
to be saved, but it must be done intelegently. I have helped scrape the remains of 2 climbers (separate events) from the ground that were using good equiment they used improperly; that's how serious it is.
The forces involved? Here are some calculations. Some is catamaran
Sail Delmarva: Sample Calculations for Jackline Stress and Energy Absorption
Ideas in general. Some is catamaran
Sail Delmarva: Climbing Gear for Sailors--Jacklines and Harnesses for the Unemployed
And this about shock absorbing tethers. Shock absorbers are required by OSHA and the military and I believe most of the tether failures we have read about were the result of unsustainable impact forces. If you don't think this matters, secure a conventional tether to a rigid point, get about 6 feet of slack and a good running start as though you were thrown by a wave, and then call us from the hospital (broken ribs).
Sail Delmarva: The Case for Softer Tethers
There are dozens of factors to consider, and each boat is different:
* Can you get back on if you fall of?
* Will the jackline be perminant? Mine are. Then consider UV very seriously.
* How wide are your side decks? What is the worst case fall?
* One leg or 2? Most people are going to 2-leg tethers as that is the only way to stay on the boat in all cases.
* What is the proper length? 6'/3' is standard, but shorter may be required on some boats.
* Where to run the jacklines
* Will you also use hard-points?
* How does the harness fit? With clothes?
* Where do you sail and how do you sail? The requirements of a relaxed coastal sailor (me), solo ocean racer
, and fully-crewed racer
* What sort of boat?
I do not mean to be harsh, really, but the OP's tethers scare me silly in several ways. They need to be trashed. Homemade tethers can be economical and safe, but these are not.
* The slides are of unknown strength and may cut the webbing. A water knot
is a better known quanity and can be tied in a few seconds. It is a much safer choise for home-built, the safe choise of climbers for many decades.
* The carabiners are a complete unknown. About all I would trust them with is a fender
. Climbing carabiners are quite inexpensive, the wire gate sort quite corrosion
proof, and they are of know strength. However...
* Carabiners without a locking function and a quick-open function are scary. It is easy to unclip a regular biner from a u-bolt, almost a party trick. Just take the tether and rotate it with the gate facing the bolt. It is acceptable to use a locking biner at the jackline end, but the harness ned must quick release.
* These carbiners are not so easy to use in the dark or with gloves.
* Webbing. Can't say for certain, but I would be more comfortable buying
webbing that was rated for climbing and of known stregth (4,000-pound plus).