A demonstration of how to tie the figure eight knot. For professional instruction, please visit amga.com. The strongest tie-in knot you can use is the figure-eight, which, when pull-tested, breaks at 75 to 80 percent of the rope’s full strength. The bowline is a slightly weaker knot, at 70 to 75 percent, followed by the double fisherman’s at 65 to 70 percent. The clove hitch is the weakest of the common climbing knots, at 60 to 65 percent. Read Climbing's "10 Things You Didn't Know About Knots" for more info.