Using Towlines as Jacklines?

[estarzinger]

Originally Posted by dochip

At REI (or online ar REI) you can get double wall 1-inch strapping of more than sufficient strength for jack lines at 36 cents per foot. I was turned on to it by one of my sons who is a rock climber.

I just looked. The REI 1" tubular webbing is rated at 17.8 -18.0 kilonewtons, which is 4000lbs. The ISAF minimum strength for a jackline system is 4500lbs.

So it is in fact not quite strong enough to meet the sailing sport specifications in a conventional 'single layer' jackline design. But is more than strong enough in the 'sling' configuration that I recommended (in a post way above) for DIY jacklines (and climbers also mostly used this webbing in a sling configuration), as in the sling configuration the load is split in half.

I have not tested the 'UV aged strength' of this particular sort of webbing. I know the colors fade dramatically but I dont know specifically what effect it has on strength. However based on other 'UV aging' tests, I would guess the strength drops very roughly by 50% after 2 years of continuous UV exposure, which means again, the sling configuration/design (or running dyneema down the middle of the wedding tube) is preferred to the more typical end loop design.

[Scout 30]

The biggest issue with jack lines & tethers is stretch. Accounting for stretch your tether needs to be short enough to keep you on deck. Being drug along side the boat is a bad way to go. With that in mind polyester line would be superior to nylon.