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Safety/strength loss All knots or hitches cause some strength loss in the rope they are tied in through the creation of bends in the fibers that make up the line. Thus, knots that minimize the strength loss of the rope — or put another way, retain as much of the rope strength as possible — are the best choice, particularly in rigging operations where lines and knots are exposed to a great deal of dynamic forces. Unfortunately, there is currently no readily reliable source for information on the relative merits with regard to strength for different rigging knots and hitches. However, research done by organizations and individuals such as Dr.Brian Kane from the University of Massachusetts is begin- ning to fill this void; and hopefully will soon result in comparisons that tree crews can take advantage of when making knot choices. Security Security, put quite basically, is how well or poorly the selected hitch or knot stays where it is placed/tied without slipping, moving or letting go of the piece to which it is attached.Obviously, this factor is important in the use of all knots or hitches, but particularly so in rigging knots. In addition, certain species with slick bark or wood may stay secure with a standard hitch, but only if additional turns or “tweaks” are made in the knot. Ease of use Ease of use is a factor in knot selection that can often be overlooked by the casual user.The reality is that a knot may be very safe/strong and secure, but so complex that it takes a great deal of time to tie and untie — leading to possible safety or effi- ciency issues. Typically if a knot or hitch is very complex, requires constant maintenance, and/or takes a great deal of time to tie/untie, mistakes are going to be made in its use; and in all likelihood there is probably a perfectly acceptable alternative knot or hitch available — without the baggage. Running Bowline with half hitches or marls This knot is often used to terminate the rigging rope at a piece or branch, with the half hitches or marls added for security or to hold the piece/branch a certain way once it is cut free. Rope strength research on rigging lines has shown that the Running Bowline actually has more strength without any marls or half hitches; and the addition of them actually decreases strength. As a result, marls and half hitches should only be used in cases where there is a concern about the piece’s orientation or that the branch might slip free from the Running Bowline, because they do not add any strength, and, in fact, decrease rope www.arborage.com Running Bowline cinched up against the piece. strength.This hitch is simply a Bowline tied around the standing part of the line. It is created by passing the end of the line around the piece or branch, making a loop in the line, passing the end of the line around the standing part (capturing it), then feeding the tail up through the formed loop around the upper standing part of the line, and back down through the loop.The Running Bowline is intended to cinch up or choke against the branch or piece when loaded. Clove Hitch with two half hitches One of the most common ways to attach a line to branches or pieces of wood, particularly among traditionalists, is the Clove Hitch. It is certainly an effective hitch when tied correctly, although it does require more line to tie than some of the other hitches discussed here. It can also have a tendency to “roll out,” meaning it must be “backed up” with two half hitches. In the Clove hitch the working end of the rope is passed around the piece/branch, captures the standing part of the line, goes back around the branch, and comes out beneath the loop created by the first turn around the branch. When it’s done correctly, the line should exit on opposite sides of the hitch, with the piece of line on top running diagonally. Once again, it must be backed up with two half hitches tied around the standing part of the line. Halter hitch The Halter hitch, a rigging knot observed being used by Wenda Li and Mark Cooke of Ontario is, like the Running Arbor Age / May/June 2011 13