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How to Tie a Double Blood Knot for Fishing

The Double Blood Knot is used for joining two lines of similar diameter. It is a common method for attaching monofilament lines of similar diameter and is relatively simple to tie.

Double Blood Knot Step 1:

Double Blood Knot Step 1:

Lay both sections of fishing line across one another. Wrap the mainline 4-5 times (6-7 times for braid) around the other line.

Double Blood Knot Step 2:

Double Blood Knot Step 2:

Pass the tag end back and through the fork created by the crossing of lines in step 1.

Double Blood Knot Step 3:

Double Blood Knot Step 3:

Wrap the spooled line around the mainline in the same fashion as step one.

Double Blood Knot Step 4:

Double Blood Knot Step 4:

Pass the tag end of second line through the middle twist, making sure it enters from the opposing direction of the previous tag.

Double Blood Knot Step 5:

Double Blood Knot Step 5:

Moisten the knot with saliva, and while holding the long ends pull the knot tight, gently but firmly. Hold firm for a few seconds before clipping the short ends close and the knot is complete.

Knots Description

How to Tie a Double Blood Knot for Fishing

The Double Blood Knot is used for joining two lines of similar diameter. It is a common method for attaching monofilament lines of similar diameter and is relatively simple to tie, retaining 70 to 75 percent line strength. It is suitable for lines up to 30kg (65lb) breaking strain, however, the wider the difference in line diameter the weaker the knots strength. If one line is slightly thinner you should increase the number of turns for that thinner line. If the diameter varies even more, double the much thinner line, creating what's known as the Improved Blood Knot. The Double Blood Knot is a very tidy knot on completion and is therefore very popular. Do not confuse the barrel knot with the Double Blood Knot. The Barrel Knot wraps its line towards the centre of the knot, whereas the Double Blood Knot wraps away from the centre. The Barrel Knot is better suited for lighter lines of less than 4kg.

Applications for Fishing

Line Classes: Light to Medium
Line types: Monofilaments, super lines, cordage.
Retained Breaking Strength: 70% to 75%
Application: Joining two lines similar in diameter size


If you don't go fishing because you think it might rain you will never go fishing. This applies to more than fishing.


There are basic rules that apply to the tying of all knots in nylon monofilament, copolymer and cofilament lines. These rules apply in differing degrees to most of the knots, splices and hitches formed in multi-strand materials, such as Dacron, Micron, braided nylon and wire or cable leaders.
Knowing and adhering to these rules will reduce the incidence of knot failure in your fishing endeavours.
RULE 1: Be thoroughly familiar with all the knots you tie and continually practice the tying of those knots.
RULE 2: Always lubricate knots before tightening them, either with saliva, water or another similar lubricant. Knots tied in nylon monofilament, copolymer and cofilament lines are highly susceptible to heat friction.
RULE 3: When tightening the knot, do so gently but firmly. Do not draw the knot quickly as this can generate heat damaging the line. Give a few test pulls on the newly tied knot.
RULE 4: If you are not happy with a knot, always re-tie it until you are satisfied. Remember that a knot is effectively the weakest link between you and the fish and the stronger and better tied it is, the more chance you have of catching fish.


Tags should be trimmed to an appropriate length and trimmed with a pair of clippers or a knife as opposed to teeth.  


Knots fail for a number of reasons. Slippage is the most common and is usually due to insufficient wraps in the knot or trimming the tag end too short. Slippage is also a major factor in the second common cause of knot failure – heat damage due to friction. Insufficiently tightened knots often fail when sudden pressure is applied to them, such as the strike of a fish.
Lastly, knots can also fail when one strand of line cuts another. This is most common when lighter lines are joined to heavier, thicker lines. In knots where one line cuts across another, such as in the Overhand knot, the strength of the knot is reduced by as much as 50%. In all knot tying the aim should be to reduce the chance of failure and retain as much line strength as possible.


Knots in light lines, or lines under 3kg, pose unique problems. Small errors in technique will cost you more when tying these knots as opposed to in heavier line. Extra care should be taken with light line knots and any knot modification or improvement should be utilised. Using an extra wrap or two in a specific knot is a good idea in light line. Doubling the line is also recommended to strengthen the knot. Always leave a sizable tag end when tying a light line knot.


Heavy line knots have their own associated problems. Most problems are related to the physical difficulties of twisting or wrapping thick line. Knots on line between 25 and 100 kilos can be tied, but need modifications. Firstly, twists and wraps in knots need to be reduced. Heavy line knots also need to be tightened with care and up to 50% of the lines breaking strain in pressure needs to be applied. Pulling the tag end of the line is also advisable. Finally, melting the tag end to a stopping blob using a flame is worth doing, whilst taking care no to damage the main line. 


Most experienced knot tiers use their hands, fingers, mouths and even feet to tie knots. Mastering knots will invariably require you to use your limbs in a dexterous manner for the best results. Developing your own personalized style will serve you well. 


It must be remembered that line offcuts are a marine hazard and stay in aquatic ecosystems for a long time posing a series of threats. Line offcuts should always be collected and disposed of or recycled. There is no excuse for tossing away used or broken fishing line. 


Terminal tackle is the name given to all fishing essentials such as hooks, swivels, sinkers, floats, rings, lures and flies. Basically anything attached to lines to catch fish. Knots joining terminal to line are the most important an angler needs to master. Anglers should become proficient in at least three knots for attaching line to terminal that suit their particular style of fishing. 


Knots for joining line are mostly useful when assembling leaders, particularly tapered leaders. They are often used when a tangle needs to be removed from the middle of a line or when an additional line needs to be added to existing line. 


Andrew Galwey is the publisher of Australia’s most successful trailer boating publication, Trailerboat Fisherman and Australian Boating, dedicated to the cruiser enthusiast. He developed the Internet site www.marinews.com back in 1996 as window to pass on some of his skills. Fishing, boating and the art of knot tying are certainly skills he’s mastered well.
As a fishing enthusiast, fishing both commercially and recreationally, Andy developed a fascination and skill for the art of knot tying. His 40 years of both working the land and boating has seen those knot tying skills extended way beyond fishing knots and into the world of rope knots as well.
Marinews would like to thank Andy for his support and hope you not only learn from this excellent section on knot tying but also get many hours of enjoyment from it also.

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