More details about the The Sheet Bend
Uses: The Sheet Bend (ABOK # 1431, p 262) is recommended for joining two ropes of unequal size. The larger rope must be used for the simple bight as shown. It works equally well if the ropes are of the same size.
It would replace the Reef (Square) knot except for the awkward fact that it has to be tied with both ends loose in your hands with no load on the ropes (The reef - with all its faults - can be tied tight against a sail, or parcel, and usually stays tight while the second half hitch is tied).
Double Sheet Bend When the ropes are markedly different in size, the bitter end of the smaller rope can be taken twice round the bight in the larger rope to create the double sheet bend.
Structure: When correctly tied the two ends lie on the same side of the knot. The alternative version - with the ends on opposite sides - is less reliable.