The Reef or Square Knot
is most frequently used, as its name implies, in reefing sails. First make a plain overhand knot, as in [Fig. 139]. Then repeat the operation by taking the end and passing it over and under the loop, drawing the parts tight, as shown in [Fig. 140]. Care should be observed in crossing the ends so that they will always lay fairly alongside the main parts. Otherwise the knot will prove a granny and be comparatively worthless.
Figs. 139 and 140.—Square or reef knot.