1/2" Multiline II

Straw

Hi all,
I just had a guy give me a partial spool of New England bull rope 1/2" Multiline II for free! I pulled it off the spool into a bag and it is around 235' long. New England's website has it listed at 5,800 lb tensile strength. Thats the breaking strength correct, not the working load? I am wondering what the working load of this rope would be. Should I use the 10-1 rule for it? This is the link to the page on New England's site about this rope.

New England Ropes - Product Details

Thanks, Straw.

Eric Frei

In Oz we have a 1/6th rule not 1/10th, ropes are a lot stronger in the southern hemisphere it appears.

There has been a lot of debate over time about the 10% rule, it is seen as overly conservative. To get a 10ton rope so you can rig 1 ton does seem overkill, especially in a pre-tensioned non dynamic loaded scenario.

You'll here terminology like "cycles to failure".

If a rope never exceeds say 10% of it's breaking strength and is well looked after it can last a very long time. On the other hand, load a rope to 90% of it's breaking strength often and it will bust one day.

Once a rope has been loaded to breaking point then it becomes very inconsistent for it's new breaking strength, it can bust anywhere along the loading curve. So if you do bust a rope, chuck it out.

There is a lot of dynamic loading when topping out or lowering logs so factor that in.

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Straw

Thanks Ekka. The reason I was asking concerning this rope is that they had this printed at the bottom of the page.

"Working Loads:
No blanket safe working load (SWL) recommendations can be made for any line because SWL's must be calculated based on application, conditions of use, and potential danger to personnel among other considerations. It is recommended that the end user establish working loads and safety factors based on best practices established by the end user's industry; by professional judgment and personal experience; and after thorough assessment of all risks. The SWL is a guideline for the use of a rope in good condition for non-critical applications and should be reduced where life, limb, or valuable property is involved, or in cases of exceptional service such as shock loading, sustained loading, severe vibration, etc. The Cordage Institute specifies that the SWL of a rope shall be determined by dividing the Minimum Tensile Strength of the rope by a safety factor. The safety factor ranges from 5 to 12 for non-critical uses and is typically set at 15 for life lines."

I was estimating on the high side and will probably only use it for directional tensioning. Was cool to get it for free though, brand new on the spool

Straw,

elloppo

IN oz the Australian Standard for life support ropes gives a guide of a safety factor of 1/10th for climbing ropes.

For rigging they can be 1/5th. Where shock loading is an issue such as in tree work a higher safety factor should be used.

tying a bowline in your rope reduces the strength by 35-40% straight up.

take into account that a shock load when blocking down can be 7 - 10 times the weight of a load. We have done load cell testing where a 200kg log went 2 ton in a worst case scenario - this is backed up by arbormaster training stats in the US.

It all depends on how long you want to keep your rope in service. If you work with a higher safety factor your rope will last longer etc. if you hammer the shit out of it it wont last too long at all.

Steve Tipton

That's good rope, I use it in 1/2" and 5/8"

It'll last a long time if not abused.

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Heightmaster