The double overhand knot or barrel knot is simply an extension of the regular overhand knot, made with one additional pass. The result is slightly larger and more difficult to untie. It forms the first part of the surgeon's knot and both sides of a double fisherman's knot. According to The Ashley Book of Knots, "A double overhand knot tied in a cat-o'-nine-tails is termed a blood knot." When weighted, it can be difficult to untie, especially when wet. The strangle knot is a rearranged double overhand knot made around an object. It is sometimes used to secure items to posts.

Instructions for tying

Alternatively, the working end of the rope can be wrapped around the standing end twice, and then passed through both resulting loops. Both methods result in the same knot, though the latter is easier to dress in the compact finished form. With either method, more loops can be included to make a longer multiple overhand knot (which is also known as a barrel knot or blood knot).