The heaving line bend is a knot for securely joining two ropes of different diameter or rigidity. It is often used to affix playing strings to the thick silk eyes of an anchorage knot in some stringed instruments. In nautical use, the heaving line bend is used to connect a lighter messenger line to a hawser when mooring ships. It is knot number 1463 in The Ashley Book of Knots, and appeared in the 1916 Swedish knot manual Om Knutar.
The heaving line bend is similar to the sheet bend and the racking bend, and may be used to pass a thick rope to a distant receiver by first throwing the end of a thinner rope which may be weighted with a monkey fist or a heaving line knot.