1/2" nylon solid braid vs.

[samsquatch]

OK gang, here's a chunk of 1/2" rope that'd hard to say no to based solely on price:
https://www.northerntool.com/shop/tools/product_200635737_200635737
Someone give me a reason to not purchase this! I would like the 300' to assist in longer mechanical advantage situations - but will this rope hold up in a 5:1 rigging situation?

What are other reliable options, 1/2" stable braid for 4x the price?

EDIT: Further research shows the diameter may not be 1/2" (maybe more like that "3/7" stuff sold on eBay that I've purchased before. If it's that crap, it's not real 1/2" rigging line. Would work great for taglines, accessory cordage, etc. though.

 

[treebilly]

Let us know how it works out but I’ll stick with stable braid. I didn’t read to much on it because of the low breaking strength. How’s the stretch factor?

 

[evo]

its nylon, strechy strechy

In a 5:1 or such the lower breaking strength doesnt bother me. I bet its not uv stabilized, or missing some element.. Could just use it as a very light duty junk lowering line, or a keeper overnight for a tie in or rigging point

 

[samsquatch]

its nylon, strechy strechy

Stretchy can be good for rigging - not so much for when trying to get good MA, static rope better for that.

In a 5:1 or such the lower breaking strength doesnt bother me.

It should! A 5:1 system will put 5x the input force on the load leg of them system! EDIT: sorry I see what you mean, it doesn't bother you as much as it would if you were, say, negative rigging a spar. But what about those times when using MA to lift a large limb - when you need several hundred pounds of lift before cutting & dropping all the limb's weight into the system? Still seems like a low SWL to me...
The only published figure I could find for this spool of rope is 420lbs or 473lbs SWL. Which I think may not be too far off of a comparable arb line - i mean, 5400 MBS with a safety factor of 10x is 540lbs SWL, right?
Some user reviews of the rope on Amazon list MBS around 5000lbs, but I'm not considering those published.

 

[evo]

Nahh bro, if used in a fiddle block each leg of rope sees 1/5th the load

 

[Jehinten]

Stretchy can be good for rigging - not so much for when trying to get good MA, static rope better for that.

It should! A 5:1 system will put 5x the input force on the load leg of them system! EDIT: sorry I see what you mean, it doesn't bother you as much as it would if you were, say, negative rigging a spar. But what about those times when using MA to lift a large limb - when you need several hundred pounds of lift before cutting & dropping all the limb's weight into the system? Still seems like a low SWL to me...
The only published figure I could find for this spool of rope is 420lbs or 473lbs SWL. Which I think may not be too far off of a comparable arb line - i mean, 5400 MBS with a safety factor of 10x is 540lbs SWL, right?
Some user reviews of the rope on Amazon list MBS around 5000lbs, but I'm not considering those published.

Although climb lines are given a safety factor of 10, it's rare for any other ropes (outside of climbing/rigging) to be given this. This can lead to two ropes having a similar WLL, but having 1,000s of pounds difference in MBS. I believe hardware store rope usually have a safety factor of about 5.

 

[samsquatch]

Nahh bro, if used in a fiddle block each leg of rope sees 1/5th the load

I think we're saying the same thing - you're saying that each leg sees 1/5 of the load, and I'm saying that the load sees 5x the force exerted on the input leg; I think I see the confusion, I'm referring to a situation when the fiddle block is not attached to the load but to a separate anchor.. which I guess would be pretty rare? Normally one would want the block on the load I suppose.

EDIT: I see - in a MA situation, the block is always traveling with the load. If both blocks were stationary with the last leg out to a load, no MA would be take place just a number of redirects. I get it now

 

[JeffGu]

The safety factor isn't a property of the rope, it's an expectation of the end user. We tend to rig things from one location to another with every expectation that the load will be moving fairly fast, will drop and bounce to an alarming degree, etc. That's fairly unique to tree work. A crane operator does everything they can to deal with static loads, and attempts to keep any movement slow and predictable. A 5:1 safety factor allows for the occasional light bouncing or slight drop. If you're hanging on a climb line, a two foot drop or a big swing makes a 10:1 factor necessary because a human being that is conscious is very seldom a static load. Our rigging techniques are pretty brutal, so using 10:1 allows for more severe shock loading than what you'd expect from a crane operator unloading shipping containers down at the docks. If those guys let loads swing around and drop like we do, the death toll would be horrendous.

Your fiddle blocks are for handling loads that are mostly static, like a crane operator deals with. It isn't meant for negative rigging or playing Tarzan with big logs. The 5:1 factor is fine for the device as long as you keep movement slow and predictable and don't let the load freefall more that a few inches.

A polyester 3-strand or 12-strand rope will work well, and they're cheap. A kernmantle climb line of 10mm works really well... strong and light. Calculate your 5:1 safety factor from the rope's MBS and try to keep the load at or below that. The safety factor will compensate for minor miscalculations (that's what it's for) but intentionally pushing your luck pretty much wipes that out. It also allows for the rope wearing and aging, etc. but you still have to play by the rules and keep shock loading to a minimum, and load speeds nice and slow (unless, of course, you want the thing to slam into the ground, in which case you don't need the MA).