If'n ya look hard; you can see that even though the Blake's supports on a single leg to the saddle from the bottom of it's 4 turn coil, that it also crosses the loaded leg over the leg going to the top of the coil to pull on it too. i think this places a Blake's more with all the rest of the hitches that pull thier 4 coils closed all at once, from top and bottom. This kinda leaves the Taughtline alone as far as mechanics i think, save for the Tarbuck(Natural fiber rope era friction hitch, not pictured); that just majorly pull a round turn closed i think.
Friction Hitch Lineup at MTL
New Friction Hitch Page in Progress at MTL
Mark Adams did an excellent article on these hitches in Oct. 04 Arborist News-Climber's Corner that Tom/Mark have archived with several other pieces of theirs under "Articles". He teased about a followup article too, that i hope he comes thru with.
When making the Blake's it is easy to make a SuiSlide instead; just by the final move with the bitter end/working tail. The way that happens, is a common concept in a few of our working lacings to get the most secured pinch and hold on to the bitter end most securely, to give the lacing most security. By both the amount of pressure direction and the direction of rotation. Which on a 'lifeline'/sliding/frition hitch is of course of utmost importance. Likewise any open tailed friction hitch (one that both legs of friction hitch do not connect to saddle) needs a stopper knot, even though Blake's does sit on it's own tail/bitter end faithfully like an anchor hitch.
i think the sliding hitch strategy works cuz' when you pull down on the hitch in DdRT, you are actually extending that leg of line, and the more static leg of line to saddle, ttries to take the load. Just as it would if it's partner leg was tearing, more elastic, or being lowered. The static leg will take the load. So the hitch loosens up as it isn't loaded, then slides. If, we do the same on SRT, there is no other line to switch the weight to, so as we push down on the top coils, the bottom ones just sieze more to the line in response. For so much hold is needed to support, the system tries to support, so the loosened top coils need the bottom ones to grip tighter to make up the diffeance, and so they do. In DdRT only half the weight is on hitch to start, then weight swithces to static leg, then you are slidning/not supported totally, so pull on hitch is less than 1/2 weight. The softer loading, making the differance in the ability to slide. The 4 coils giving sure, death grip to stop, the preceding buffer (in all but Blake's), keeping the coils from siezing to the line etc. All in concert to not overload friction hitch 4 coil choke death grip to siezing on the line.
The non-Tautline hitches work on a base of 4 continuous gripping coils on top i think. Blake's unique, for it just disturbs the bottom 2 coils bite, allowing slide, as weight switches to the static leg/dead ended to saddle in DdRT. The 4 and 6 coil prusiks, bite more and are presented more for completeness. The rest of the friction hitches shown have a 4 coil death grip on line, but the loading preceded by another single choking coil. To buffer loading to the 4 coil death grip, that could sieze; but the preceding buffer keeps the forces in the more manageable powerband of performance for the friction hitch. VT family giving a buffering list of line bends, rather than the single choking coil. If the preceding coil buffer was not a simple turn, but the much, much better round turn strategy, it would be too good; have too much grip. The much lesser reliable single turn; thereby finding place here by definition.
It should be easy to learn new hitches, if they are based off of the same forms, with slight mechanical alteration to taste with this view.
With a lanyard on, i generally have 2 free hands. A distel so similar to tautline in lacing(but not mechanics), should be as likely a candidate for a 1 handed tie; save for linking last leg to saddle.
Hidden Button to enlarge photos below
:alien:
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