The blood knot is one of several fly fishing knots that is used to connect two fishing lines together like a leader and a tippet. The end of a tapered leader is about the same size as a tippet. The Albright Knot is better suited for lines of different diameters. This knot makes a lot of sense when you build it, but does require some practice to be able to make is smoothly while out fly fishing. If I have not used this knot in a while I practice this at my home a day or two before going fly fishing.
There are many terms used when describing tying fishing knots, marine knots, and other types of knots. Two words I will use in the descriptions of my favorite knots will be
When beginning to learn to tie fishing knots, you will need to learn to leave enough extra line on your working end to finish the knot. With practice you will learn to estimate this very closely. As you progress through tying the knot you will quickly learn to tell if you will run out of line on your working end. Sometimes you will need to just start over because you will not have started with enough extra line on the working end to finish the knot. The rope used in these pictures is of course much bigger than fishing line - as a result the knots in these pictures are much bigger than you will make with your fishing line.. When done tying any knot trim any excess line on the working end so that it will not be in the way.
Blood Knot Step One and Two
The blood knot actually has two working ends. Lay the two ends of the leader and tippet for example along side of each other. In the field or next to a stream you will have to learn to do this in your hands. Notice in the picture above that this actually shows the second step by looping one working end back towards the second working end.
Blood Knot Step Three
Step Three involves forming 8-10 loops with the working end of the line you just made the loop. As you make these turns or revolutions you will see the loop getting smaller as in the photo above. Keep this loop open by holding it as you make these revolutions. In the example above I shortened this process using only showing 3-4 turns. With a common leader and tippet you should attempt to make 6-10 turns.
Tighten the Knot
This step completes the first half of this knot. Pass the working end of the line you have been using through the remaining loop you have formed. Then tighten this knot down onto the working end of the other line. Do not let the working end of the second line slip through this knot just formed. The second picture shows this first knot tightened down. What is going to happen is the second working line is going to form a knot just like this one you just formed. Then when you pull the standing parts of both lines these knots will slide together and hold firmly.
Begin Side Two
Now begin the same process on the reverse side. I will simply supply 4 additional pictures showing the final steps to completing this knot. When done trim the loose ends.
Side Two Loop Arounds
Working End Through Loop
Tighten Second Knot
Finish Blood Knot - Pull Together and Trim