Page 238 - Buck Tilton - Outward Bound Ropes, Knots, and Hitches 2 ed.
P. 238
Thread the working end of the second rope
through both loops of the double overhand knot
in the first rope, as shown in the photograph.
After being weighted the two double overhands form a
tight bond that simply stays put. For this reason, climbers
will use this knot to create a short sling or loop to aid
climbing. Fishermen often call the double fisherman’s knot
the grinner knot for reasons not completely understood.
Perhaps it’s because it looks to some like open mouths prior
to being tightened.
