Watch this boating instructional video to learn how to tie the double fisherman's knot. The double fisherman's knot securely ties two ropes together or can be used to tie the ends of rope or cord together to form the loops. Another use for this knot is to make another baoting knot more secure by tying this knot with the tag end of the rope behind another boating knot, a practice common to mountain climbers. In that case, you are effectively tying one half of the double fisherman's boating knot around the standing line of the other knot. This how to video will surely make you a pro at tying the double fisherman's knot.