Blake's hitch is a knot that is used by people like mountaineers, rock climbers, tree climbers and cavers who need to climb up and down ropes. It is one of a class of slip knots called friction hitches, which hold tight when weight is applied to them, but can be moved up or down the rope they are tied to quite easily when no weight is applied.
Although this knot is most often called the Blake's hitch, it was actually first described by Heinz Prohaska in Nylon Highway, a caving magazine, perhaps as a modification of the Hedden knot. Since James Blake introduced the knot to the tree climbing community in the arborist publication Arbor several years ago, it's been referred to with his name, particularly by tree climbers, who use it as their main ascending knot. Prohaska's name is given to other knots of his own design and 'Blake's' is easier to say, so the name will probably stick.
Good and Bad
Blake's hitch is most popular for use in the two-rope technique for recreational tree climbing, a relatively recently discovered activity that attracts the very young and old, and the athletic and not so athletic. One reason for the knot's popularity is user-friendliness. It is easier to tie and use than the Prusik knot, which is a standard knot used by other types of climbers for ascending or as a fall-stopping safety measure. Another important advantage is that it will grip much better when loose than will the Prusik. It is also easy to slide or untie after a heavy load (you, for example) has been applied, whereas the Prusik tends to tighten up after a while and require two hands to break loose.
The major disadvantage of this knot is that it creates a point of concentrated friction inside the knot. This isn't a such problem for ascending, but the friction can generate enough heat to damage the rope during a long descent that is anything but very slow. None of the friction hitches are good for a fast rappel, but Blake's hitch is least suitable of all. If you're after the excitement of a flashy and impressive fast exit from your tree, cliff, etc. and you accept the risk of making an unintentionally severe impact on the environment (i.e., the ground), then make your descent with a special descender device designed for rappelling.
Description of knot tying really needs step-by-step illustration, but if you try this with rope in hand and a reasonable degree of stubborn refusal to give up, you will likely end up with a good Blake's hitch sooner or later.
What we are going to do here is take the end of a rope and tie it to another part of the same rope, somewhere in the middle. That will make a loop with a sliding knot, like a lasso. It's a good idea to work with the rope laid out on a surface, but you could also work with the rope hanging from a hook, tree branch, gallows or other convenient support. This description is for a half-inch wide climbing rope, which is very flexible. You can scale the dimensions up or down for the size and stiffness of the rope you are using.
- Hook. Take one end your rope and form an upside-down hook shape with it (or throw it over a tree branch, etc.). The open part of the hook should be on the right side. The upside-down U part can be as tall as you please, but you won't have enough rope to finish the knot if it is too small. I'll call the long part of the rope on the left, the part that always remains vertical, the standing part. The end part that we will be getting mad at while trying to tie the knot is called the working part.
- P. Now take the working part in your right hand at about 18 inches from the end and draw it over to the standing part to form a letter p with the 18-inch-long working part pointing off to the left of the standing part.
- Coil. Hold the point where the rope crosses itself in one hand and wind the working part under and around the standing part four complete times, loosely. Move up the rope as you wind so the windings form a loose but untangled coil. The working end, shorter now, should be pointing to the left again.
- Complete. Bring the working end down to the bottom of the knot, below the lowest winding, and pass it under the standing part. Now, bring the end up through the bottom two coils so that it exits to the right. That completes the knot, but now you have to tighten and dress it. Here, dressing means to make the knot neat so that the coil windings are all parallel like in a hangman's knot. The knot will not work unless it is tied and dressed correctly. Pull on the two parts of the rope that enter and exit the knot to tighten it as you work the coils into alignment.
- Test. If you tied the knot correctly, you can grasp it and slide it up or down the standing rope to tighten or loosen the 'noose' (loop). To test the knot's gripping ability, hold the standing part above the knot and pull down on either the loose end or the part of the loop that enters the knot. Tied properly, the knot will grip the standing rope tightly and not budge. If the knot is too loose, putting weight on it will distort it and make it look messy, although it may still grip to some degree. Done right, the knot will keep its dressed shape.
This knot will hold your weight easily. You can use it to climb up the standing rope or to descend the rope in a controlled manner. If you ever use this knot for actual climbing or safety purposes, remember that you might die or incur serious injury if the knot is not tied properly and used properly. Hands-on training by an experienced climber and adequate practice are essential.