A blood knot, also known as a barrel knot sometimes, is one of the most used knots in the fly fishing world. It dates back hundreds of years and was used on sailing boats at the end of whips or cat o nine tails for the purpose of drawing blood when punishing an unruly mate on board, hence the name blood knot, and is used in sailing today as a stopper knot.
In fly fishing, we don’t use it to whip other anglers off our fly fishing spots but instead to join two lines of different diameters to make leader connections on our fly fishing leaders tapering down from your leader material to your tippet.
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How to Tie a Blood Knot
The blood knot is a quick and easy knot to tie once you have practiced it a little. Here are the directions on how to tie a blood knot.
Take the two pieces of line, such as your tippet and leader sections, and line them up horizontally side by side, overlapping by about 6 inches.
Grip the two sections of line in the middle of where they overlap with your thumb and forefinger and create a gap between the two lines, this will be the hole your tag ends go into at the end.
Take the tag end of the leader or tippet material with your other hand, it doesn’t matter which first, let’s say you’re using the mono leader first and wrap it around your tippet line 5-7 turns. Now take the tag end of the mono and slot it through the loop you made in step 2 and hold it.
Repeat the process in step 3 but with the other diameter line, your tippet, in this case, wrapping it around the mono for 5-7 turns in the opposite direction and then putting the tag end into the same loop as the other tag end.
Make sure the tag ends are coming out of the loop in opposite directions for a quality blood knot.
To finish the blood knot, wet each strand with saliva and slowly pull both main lines apart. You should start seeing the turns moving towards each other. Keep going until they form a blood knot and pull a little harder to tighten the knot.
Now trim the tag ends of each of the lines, leaving a little bit of line so the knot doesn’t slip, and you have successfully tied a bloody knot.
Tip – I always seal my blood knots with UV knot glue to add some extra strength and so the tag ends don’t catch on my fly rod when I cast make it easier to fish with. Just put a dollop on there and leave it in the sun for a smooth, sealed, easy to cast blood knot.
Here is a Youtube video that will show you how to tie a blood knot:
Is the blood knot strong?
Yes, the blood knot is pretty strong and when tested the blood knot provides 83% of the strength of the diameter of the lines being used. So if your using 15 lb or 0 x sizes the blood knot will break at 83% of 15lbs with is 12.45lbs. But remember, this knot uses two different size lines, so always measure for the lightest weakest one.
How do you tie a blood knot quickly?
One of the bests ways to tie a blood knot quickly is through practice but you can also speed up this knot’s process if you use a match stick to maintain the loop the tag ends go into.
You’ll find that you lose the loop often when you first start learning this knot and it can be time-consuming but if you use a match or twig to keep the loop open, you can always find it for your tag ends.
How many turns in a blood knot?
As I mentioned above you’ll need to use 5-7 turns with these knots to ensure 83% knot strength. Any less and the strength of the knot goes down. I always use 6 turns as it’s my lucky number.
What are blood knots best used for?
We have touched on this but just to avoid any confusion, blood knots best uses are when you need to join two different size mono lines together, like a leader to tippet. They can also be used as a stopper knot in sailing.
They are not good for use with braid, so do not use them for a braid to braid, or braid to mono connection.