Pulleys

[TheTreeSpyder]

Mike, i've tried to draw that out too; din't do that well! But from the 'stolen stacks' i have one like it perty slick, that i made sure i held on to. This is a neat trick, if just to show creativity of mind, what one can do and working with these simple tools, IMLHO.

For those unfamiliar, this can take about 4 legs of line for the line running in the pulley; another leg+ for the support line. In use the support tail doesn't have to be anchored; it is just for re-inverting system to remove the block; so a seperate tie down anchor for it isn't needed(hence rope pictured in bag). Thereby, also dropping the support load some also with this strategy. A line thrown over the support and tied down to anchor on the ground and not as Mike showed; places more load on the support, which can already be carrying double loadforce becuase of the pulley(depending on the angle of the lines coming out of the pulley).


Not used very much, but if ya done it enough to realize when it is needed and throw together quickly can be very handy IMLHO. A 2/1 system hung simiraily will give more power, reduce the support load by ~1/2 x Load; but take 6 legs of line to initiate (w/o cheating and tying a line on the end of a few legs at once to extend them for a moment).

Or something like that
:alien:

 

[Kneejerk Bombas]

Make sure you use an appropriate knot for the loop, not a splice or bowline.

 

[rbtree]

Did you mean to say running bowline, Mike?

I learned that trick from Arbormaster training. Never used it though, due to the need to isolate the anchor limb, and the amount of line needed. and the fact that I forgot about it..

 

[John Paul Sanborn]

C'mon Rog, you can afford to keep a full spool of rope for you retrievable block

 

[Kneejerk Bombas]

NO RODGER, I MEAN A BOWLINE.
A BOWLINE CAN ONLY BE LOADED IN LINE WITH THE ROPE. THIS TECHNIQUE LOADS THE LOOP, NOT IN LINE WITH THE ROPE. THE ROPE PART IS LOOSE.

 

[TheTreeSpyder]

i've tried something similar with a roundsling etc. as eye instead of bowline to beat that affect, never seemed to work as well, especially removing.

So, i've re-sorted to a Double Bowline w/Y tie off (standard knot) with success. i was afraid that a barrel/buntline/lobster class eye might cinch up and really frustrate remote removall.

What kind of knot do you use Mike? i agree there should be some pull on the mainline to work the parts properly of the bowline, don't look at the works of the knot being a highly loaded position on choking on a fair sized 'textured' support(?); especially if placed with low stress on the 'joint' part of knot purposefully as it chokes(?). Not spread apart on support, not tight up agianst restriction of choke, but functional type strategy of place-meant.

___________________________
Enquiring Minds Need to Know!

 

[ROLLACOSTA]

do any of you guys still use the timber hitch on section felling..most guys myself included use a running bowline..i havent tied a timber hitch in years

 

[rbtree]

I see your point Mike, but fail too see a problem, having just gone outside and tested the rig, without loading it though. A jacked bowline with Y tieoff would be pretty secure.

What other knot would you recommend? a double figure 8 would work but add bulk.

 

[rumination]

TreeSpyder took that illustration from Art and Science of Practical Rigging. The very next page (pg 101) has an illustration of the correct knot to use. It is described as "a variation of the bowline with a round turn and the bight in the loop". It's a pretty neat knot. Sorry I don't have a scanner, otherwise I would post it.

 

[Kneejerk Bombas]

Originally posted by rbtree
I see your point Mike, but fail too see a problem

A BOWLINE IS NOT A GOOD KNOT TO USE WHEN LOADING THE LOOP BECAUSE IT WILL PULL APART WITH A RELATIVELY LOW LOAD.
IF IT PULLS APART, YOUR LOG WILL FALL AND MIGHT HIT YOU ON THE HEAD. FOR MOST PEOPLE, GETTING HIT ON THE HEAD IS A PROBLEM, BUT YOU SHOULD BE OK.

 

[TheTreeSpyder]

Actually TreeClimber165 was Rocky before he went over 4000 posts and started over; i got the drawing from a post or email, can't remeber.

i make that to be a double jacked bowline on pg.101, kinda like Rog said; and that would be a real good use for that positioning perhaps. From what would be usually a miss-maid bowline, i didn't feel too good about that before, but didn't know it came so highly recomended.

In the slip knot method of tying a double bowline, if you pull the bight out of the working side and bend over the standing, it makes the 'Jacked Bowline' i believe.

Very good lesson and view, not sure if that is really correct/correct perhaps better than standard bowline. It would seem to me as if the standing part isn't locked, then it still kinda has the pulls on it of a cut open bowline or sheetbend(?). A sheetbend is less secure because 1 leg is 'open' w/o load on the other end of the choking ring?

i think enough maybes to at least make a Double Bowline w/Y tie off (DBY) whether jacked or not. There is also another Double bowline version, where the 2 turns aren't as a round turn, but 2 seperate choking half hitches in series, called a water bowline, that is even more secure and used underwater etc.; that perhaps would be even more correct; esp. with Y tie off.

Great Discussion and Theories into Land of Inner Workings!

 

[RescueMan]

from Art and Science of Practical Rigging. The very next page (pg 101) has an illustration of the correct knot to use

I don't much like the round turn (double) or clove hitch variations of the bowline. It seems to me that these versions don't cinch down as well as the plain jane bowline.

But what I would use for this retrievable block loop is the jacked bowline with a Yosemite backup and an overhand backup just for belt & suspenders (see attached pic).

- Robert

 

[John Paul Sanborn]

I don't do the yosemeti, btu I usually use a jacked double bo'lin', it seems to come apart much easier after heavy loading.

 

[ROLLACOSTA]

i just got 1 basic question ..is a bowline a sufficent knot for section felling..yes or no..so far though ihave not had any problems with this knot ...years ago we in the UK always used a half hitch combined with a timber hitch now this knot seems to be very rarely used

 

[TheTreeSpyder]

i trust my Double Bowline w/Y tie off for about everything.


i think in our flexible 1/2" arbo lines the 2 ring bowline strategies align and set /cinch down very well; so i thin that line choice has something to do with our different observations possibly. i favour the slip knot method of tying the bowline, which lends very well to 2 ring strategies. Especially if you keep the rings loose till setting and then pull rings tight at once form opposite ends; also very easy to lay aside half made bowline with 2 rings to lay down, hang from thumb etc. and finish quickly.

The 2 rings can be of the standard forms of roundturn or clove or girth. i favour the roundturn/double/mountaineer bowline.

i think here extending the Y tie off is part of the answer, not eliminating it. i think we fight security of the tail and loosening of the choking turn(s)(by virtue of them ending with the standing end that is not loaded) in this excellent example. i think doing the Yosemite tie off and then bring the tie off back down through the ring(s), empowers the ring to choke on the tail again, the ring being partially loaded, the problem is too much dependance on loading the standing end to empower knot holding(?) Then perhaps on to RescueRob's final hitch/lock.

i think if that passes through a 2 ring strategy even better. For me that would be make normal bowline and add extra tuck for Y+ tie off. Adding resistance to the rings moving as standing end still is loose and end of choking ring(s); make the clove hitch bowline/ water bowline i think would be 1 answer. i don't think think the tail could slip 6 ring chokes + to escape.

i think the loop of the jacked can get pinned/locked against load, if laid in right direction to do so, for more security, esp. in example given(?)

 

[John Paul Sanborn]

Originally posted by ROLLACOSTA
i just got 1 basic question ..is a bowline a sufficent knot for section felling..yes or no..so far though ihave not had any problems with this knot ...years ago we in the UK always used a half hitch combined with a timber hitch now this knot seems to be very rarely used

I use a bo'lin' over a half hitch or a marl.

The hitch holds the bo'ling tight and takes loading off the boline,

 

[Kneejerk Bombas]

With a running bowline, the bowline part isn't the weakest point of the set up. The bowline is on one side of two legs, that wrap around the log, so it's only taking about half the load.
The bend where the standing part of the rope goes through the loop is the weak spot.
A marl is a nice addition when time is plenty, and you want added security.
The bowline is a good knot, except with some stiff ropes, they tend to come untied. Soft, sublte, arborist ropes hold a bowline really well. Bull ropes are stiffer but still work good with a bowline. I have some static ropes that are so stiff the bowline kind of unties itself. For these ropes I feel I need to do some of the add ons talked about already.