Usage
The Blood Knot, a favorite of fly fishermen, is most usefully employed for joining two lines of monofilament nylon while maintaining a high portion of the line's inherent strength. Other knots used for this purpose can cause a substantial loss of strength. In fly fishing, this serves to build a leader of gradually decreasing diameter with the castable fly line attached at the large diameter end and the fly or hook at the small diameter end. The principal drawback to the Blood Knot is the dexterity required to tie it. It is also likely to jam, which isn't a concern in fishing line, which is no great loss to cut, but may be a concern in normal rope.
Also known as
ABOK
Strength/Reliability
Though the Blood Knot can be tied with as few as 4 wraps on each side, the strength is increased by adding at least 5 and up to 7 wraps to each side of the knot.
Note
As with most fishing knots, remember to lubricate the knot while tightening. Lubricating the knot, typically with water or saliva, reduces friction as the knot is tightened, preventing heat buildup that can weaken the line. This is particularly important for monofilament and fluorocarbon lines, which can be damaged by the heat generated during knot tightening. Proper lubrication allows the knot to cinch smoothly and evenly, preserving the line’s strength and ensuring a more reliable knot.
