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How to Tie the Double Uni Knot

The double uni knot is the most popular variation of the uni knot.

As its name implies, this knot simply doubles up on the standard uni knot to add even more strength to an already strong knot.

Although the double uni knot has several different uses, it’s most commonly used to connect two lines (of differing or similar sizes) together for fishing.

How to tie double uni knot step by step illustrated guide

In fact, this is such an effective fishing knot that we included it on our list of the 10 best fishing knots every angler needs to know – you’d do well to learn this knot whether you’re a recreational fisher or learning the skill for disaster prepping.

Here’s exactly what you need to know to tie a double uni knot the right away.

How to Tie a Double Uni Knot

Tying a double uni knot is simple, no matter the type of line you’re using.

Although you likely want to learn to tie this knot with fishing line, we’ll show you how it’s done with two different lengths of rope to better illustrate the process.

You can follow the exact same steps to tie a double uni knot with fishing line.

Step 1

double uni knot step 1

Overlap the ends of the lines next to each other by several inches.

Step 2

how to tie double uni knot step 2

Next, make a small loop by doubling back the free end of one line.

Step 3

how to tie double uni knot step 3

Wrap the free end of the first line around both lines three to four times.

Step 4

how to tie double unit knot step 4

Pull the end of the first line through the loop you created to form the first of the two uni knots.

Step 5

tying the double uni knot step 5

Repeat steps 2, 3, and 4 with the free end of the second line. Remember to wrap the second line the same number of times (three or four) before pulling tight.

Step 6

double uni knot step 6

You know have formed two separate uni knots. Finish the process by pulling the standing lines in opposite directions to pull the knots together until secure.

Step 7

complete double uni knot with rope

Clip the tag ends close to the knot. I use nail clippers when working with fishing line. Like most fishing knots, the double uni knot is not meant to be untied, so you can clip very close to the knot itself.

Tips on Tying the Double Uni Knot

The double uni knot is simple and straightforward. It’s a fishing knot anyone can learn.

Tying this knot works best when connecting two similar fishing lines. For example, joining two monofilament lines, even if they’re different diameters.

Things get a little trickier when joining two different types of fishing lines, especially if one of the two is braided line.

When you’re working with braided fishing line – say, when joining monofilament line and braided line – it’s important to give the braided line a few extra wraps while simultaneously giving the monofilament line a few less wraps.

So, for example, you’d want to wrap the uni knot on the braided line five times while wrapping the uni knot on the monofilament line eight times.

Adding the extra wraps on the braided side of the double uni knot will ensure that both knots hold, despite their differences.

Best Uses for the Double Uni Knot

person holding trout

The double uni knot is one of the best fisherman’s knots around.

It’s most commonly used to join two lengths of fishing line. It can be effectively used on braided, fluorocarbon, and monofilament line.

With just a slight variation, you can also use the double uni knot to connect a fishing line to a fishing hook, although a standard uni knot is typically better suited for this particular task.

The double uni knot is known for its versatility. It can be used for pretty much any type of fishing, although it’s most often used for saltwater fishing thanks to its strength. It’s the perfect knot to join two lines when going after big game fish.

You’ll rarely see the double uni knot used outside of fishing since other knots are typically better suited for these jobs.

With that said, the double uni knot is perfect for joining two lines of any length, including rope (as illustrated in my step-by-step knot tying directions above).

Use this knot to connect two lengths of rope for a variety of wilderness survival and camping tasks. Although it’s not necessarily the best knot for such tasks, it does shine in terms of ease of use.  

Once you know how to tie it, the double uni knot is one of those knots you can tie with your eyes closed – perfect for camping, hiking, and wilderness survival after dark.

Pros and Cons of the Double Uni Knot

Every angler should learn to tie the double uni knot, but it’s still important to learn its pros and cons for fishing.

Double Uni Knot Advantages

Here are the main benefits of the double uni knot:

  • Strong – The uni knot itself is a very strong knot, but the double uni knot variation increases the strength even more.
  • Versatile – You can use this knot to join braided, fluorocarbon, and monofilament fishing line. It’s particularly useful for joining two different types of line (such as braided and monofilament).
  • Easy – Once you learn how to tie it, the double uni knot is so easy you’ll be able to tie it with your eyes closed (perfect for low light conditions).

Double Uni Knot Disadvantages

Here are the main drawbacks of the double uni knot:

  • Stretching – This is more so a disadvantage of using braided and monofilament line together rather than a downside to the double uni knot, but monofilament line tends to stretch when used with braided line.

History of the Double Uni Knot

The standard uni knot dates back to roughly 1944 when it first appeared in a print publication.

At the time, the uni knot was called the gallows knot. Other names it’s had over the years include the Duncan loop and Grinner knot.  

A small variation, the double uni knot, was quickly developed due to its added strength, especially when joining two lines.

The double uni knot has long been a favorite of anglers for both freshwater and saltwater fishing with braided, fluorocarbon, and monofilament lines.

Variations of the Double Uni Knot

The double uni knot is itself a variation of the uni knot.

The uni knot is regularly used to attach a line to a hook or to join two lines together.

Although the double uni knot can be used to join a line to a hook, it’s much better suited for joining two lines together, especially when extra holding strength is desired.

The standard uni knot is a better choice for connecting a fishing line to a hook.

While it’s not technically a variation of the uni knot or double uni knot, the blood knot has similar applications for fishing. It’s a little more difficult to tie (and not necessarily as strong), but is certainly a “cleaner” knot.

Why Not Learn Some More Fishing Knots?

At Survival World, we’re set on compiling the best knot tying resources online.

To learn how to tie other knots, check out our guide to the best fishing knots as well as our full list of survival knots.

And, if you want to learn even more about survival fishing, our survival fishing resources break down everything you need to know, such as how to choose the best fishing knife.

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