Rigging with a Split Tail?

[rwbinbc]

Hello,

I have been using a split tail with a blake's hitch on a 5/8" bull rope. Is this safe to use this set-up? At what point will the blake's hitch slip? The full set-up is a 5/8" 3 strand rope with an spliced eye on one end with a heavy carabiner to choke on the tree at about 20' up, The split tail was use to adjust the distance on the rope between the chain come a long, So I could adjust the set-up easily. We where pulling trees off a fence line they where leaning over the fence slightly (not to much).

Again safe or not? Just wondering

Thanks Rob

 

[VA-Sawyer]

Don't think I would say it is 'unsafe'. You may want to try a load test between a couple of stout posts with the rig to see if it slips at a lower load than expected. I think a Prussik may give a better grip than the Blakes.
I use a rope prussik for gripping my 5/8 bull rope with the 5:1 rig. I have a number of loops made from 3/8 up to 1/2 inch rope. They are made in different lengths and I use them like I do the nylon loops. They just work better than the nylon loops for prussiks.
Rick

 

[rwbinbc]

The chain come a long is a 3/4 ton and it doesn't get stiff when we where pulling them over. The rope swl I believe is around 1800-2200 lbs and I didn't want to stress it. I was using this set-up just to insure the fall.

 

[2FatGuys]

While I've never seen a Blake's Hitch used this way, it doesn't mean it won't work. I agree that a Prussick is the traditional hitch used in this manner. We use the Prussick when setting "spider legs" and also use it to attach pulleys to the bull line when setting up "mechanical advantage" systems. Each rope / cord combination has an optimum number of wraps to work well. For us, it's a 4-loop prussick (8 total wraps) aince we are using a 3/4" bull line when we need to set up MA.

EDIT: FYI - with a 5:1 (and 2 BIG guys pulling), it isn't hard to achieve that 3/4 ton pull without a mechanical winch or come-along.

 

[PFirebird]

It's probably safe to say that using a friction hitch (blake's hitch) like that is not recommended, although it may work. I think, instead of the blakes hitch for adjusment, instead tie a bowline on a bight on the pull line, and attach the other pull rope to the loops in the bowline with carabiner etc. It's a little more work to adjust it (you just have to re-tie the bowline bght were you need it) but the bowline on a bight never fails, and can't slip. The rope would fail first.

 

[randyg]

So long as the split tail is same diameter it will work fine. I like to add one more wrap on the top end of the Blakes when using for rigging like you described. For me, I think easier to untie than prussic especially when loaded real heavy. Prussic sometimes needs a small hammer or head of a wedge to pound loop back to loosen, blakes with 3 wraps up I can work by hand to get loose. Now pull either knot halfway through the side plates of a turning pulley and you have a real picnic, not that I ever...

 

[randyg]

If you could set a line higher (using throw line/bag) you could get by with much less pull.

 

[2FatGuys]

If you could set a line higher (using throw line/bag) you could get by with much less pull.

For some people, that is a big IF...

But you are right.

 

[2FatGuys]

So long as the split tail is same diameter it will work fine. I like to add one more wrap on the top end of the Blakes when using for rigging like you described. For me, I think easier to untie than prussic especially when loaded real heavy. Prussic sometimes needs a small hammer or head of a wedge to pound loop back to loosen, blakes with 3 wraps up I can work by hand to get loose. Now pull either knot halfway through the side plates of a turning pulley and you have a real picnic, not that I ever...

We've never had our 5:1 prussicks lock up on us. Maybe we just got lucky with the combination of bull rope and prussick cord we use.

 

[rwbinbc]

Cant I make pussiks out of 1/2" climbing line to use on the 5/8" bull rope?, What would be the best knot for the ends? I do like the blake's hitch as it does untie pretty easy after a load. Just trying to be as safe as possible.

 

[2FatGuys]

Cant I make pussiks out of 1/2" climbing line to use on the 5/8" bull rope?, What would be the best knot for the ends? I do like the blake's hitch as it does untie pretty easy after a load. Just trying to be as safe as possible.

Depends on the construction of the ropes / cords. I use a 7/16" rope on my 3/4" bull line. The 7/16" lines are made into permanent loops using water knots. The benefit we have seen with the prussicks is the ease of adjusting on the line. We tried using a blakes years ago and once loaded heavily, the blakes had to be "broken" to adjust it. The prussicks seem to slide easier after loading.

But if it works for you, and you are keeping a good eye on the tail of the blakes to make sure it isn't walking, do what you know....