KNOT COMPARISON - Fig 8 (Centauri knot) vs the Uni Knot

[REEFMAN]

Many people over the years have claimed that the Uni Knot is the same as the Fig 8 (Centauri knot)

The knots make a similar "Fig 8" pattern when they are unravelled, but that is where the similarity ends. Sportfishingmag knot strength tests report the Double Fig 8 almost 15-20% stronger than a Double Uni. But the main difference between the final knots is the direction of the tag end. The Uni knot tag end ends up at 90 degrees to the mainline, while the Fig 8 tag end runs parallel. This cannot be seen very clearly when using light tackle, but I decided to highlight these differences once and for all using large diameter mono and some thick nylon rope.

The diffferences can be seen much more clearly. This is no real problem in terminal tackle, but when used in joining leaders or line joins, the Uni knot tag end will catch the rod guides every time.

[REEFMAN]

More. The Fig 8 in mono rulez!! 

[Capt. Hook]

100% Tony, the Fig. 8 works better on your guides and is definately stronger. 

[shamwari]

Great illustration Tony, thank you.

The reference to the increase in strength of the fig 8 over the  uni - are they referring to the back to back connection for mono to mono only  or also tying to swivels, hooks etc.

I would be interested to hear your own test results or those of F.A.'s of a 4 turn uni vs a fig 8 knot to a swivel, hook etc. ? I have done some very simple one vs. the other tests i.e. tie a uni to a thick hook then tie the other end to exactly the same type hook with a Fig 8. Hook one on burglar bars and put a screw driver through the other hook and pull. Using 100lb zippy mono I didnt get consistant results.

Your thoughts ? many thanks.

[REEFMAN]

Bruce, according to summarized test results I've collated from Sportfishingmag, Tackletour.com and others... (these are tests in mono) the Uni is 85% to terminal tackle... perfectly acceptable, and the same as a Fig 8. But when used to leaders as a Double Uni (back to back), the strength drops quite dramatically... right down to 66% in 50lb Mono, and probably even more in 100lb...

The best thing about the Fig 8 knot IMO, is that it is almost a frictionless knot in the forming of the knot.

Wish I had one of those line tester machines... we could make some serious inroads to dispelling certain knot myths...

[Spotted Grunter]

I am sure this has been done before, but could not find it on the site.
 
I've been playing around with the Uni vs Fig 8 and I think I have stumbled across a way to tie the figure 8 just like you would a uni with 1 subtle difference.
 
Why? Boredom for 1 and tying a figure 8 with more than  3 turns gets a bit fiddly with the loops.
 
1. Cross tag end over standing end and form a loop. This is the difference to a Uni. 
   
 
2. Complete as you would a Uni with required number of turns, 2 in this case


 
3. Tighten


4. Completed Knot



To me, this looks exactly the same as a figure 8. I have not done any knot strength tests. Works the same for joining lines, cross the 2 lines first before making the loop.
 
Reefman and other knot gurus, can you have a look and do a few test of your own to see if this will work, thanks 

[REEFMAN]

Interesting SG... Nice images!!
Will check it out when I have some time.... definitely looks better than an ordinary Uni, with the tag parallel to the mainline.
Why would you tie a Fig 8 with more than 3 loops?

[Spotted Grunter]

Sorry, meant to say with 3 loops, I always seem to lose to the 1st 2 loops when trying to secure the 3rd, especially with wet fingers and thinner line. At home no problems, on the beach very frustrating.

[dodger]

there are a few ways to tie a Fig 8 knot, I know Richard uses something similar to what you have posted

[Spotted Grunter]

Just to add to this.
 
With a Fig 8, before tightening, the tag and standing ends  both sit next to each other and exit the same side of the loop. The Uni on the other hand, both ends do not sit next to each  other and exit either side of the loop.
 
This results in what Reefman has shown in the 1st  post, tag running parallel (Fig 8) and perpendicular (Uni).
 
3 Turn Fig 8 and Uni shown in the pics below

Now, your question got me thinking Reefman (why more than 3  turns).
1. If the ends exiting  opposite sides of the loop is the only difference between the two, and visually  it seems to be the only difference, then why do we limit the Fig 8 to 2/3 turns  and make more turns on the Uni? It would be interesting to know if more turns =  greater strength. 
2. The figures quoted above,  can these be attributed to braid as well, maybe not the exact numbers but can  we assume that the Fig 8 is stronger than Uni when joining lines (braid to  leader). If this is true then why not use a 7 turn Fig 8 on braid and 3 turn  Fig 8 on the leader side. 
 
Another similar way to tie the  Fig 8 is to form the 1st loop as you would normally do. You will  notice that the loop has crossed over the standing end, this is what gets both  ends to exit the same side of the loop. Now simply pass the tag end through the  loop the required amount of times and tighten.
 
Having said all this, I have used  both the Uni and Fig 8 on terminal tackle and both have never failed me. The 7  turn Uni – 3 turn Fig 8 when using braid and the double Fig 8 on mono have also  never failed me.
 
The Fig 8 is just a much neater  knot, this is quite evident on thicker lines. I do not have any fancy line testing gadgets so my comparisons above are not scientific, just  visual differences.

[Trevour]

I was once one of the believers that they were the same knot, but have come to my senses. It is possible to ensure a uni has a tag that exits straight rather than at an angle, its all in the tentioning of the knot, but even then, its not a fig 8. To me the difference is at the other end of the knot, with the 3rd turn. The turn ends with the tag going between the two mainlines, and then straight until exit under the turns. If you look carefully you will see what I mean. If you look at the tut on joining leader fig 8 to seven turn uni, you can see in the pic before the knot is tentioned,  that the tag goes between the doubled braid and mono. This is why the knot is stronger, and why  all the turns are able to happen before the tag heads back parallel to the lines. The last turn ends around only the line that is making the knot, not the line it is being joined to, this kills a lot of tention in the line making the line able to do the turns without strangling itself or breaking under the strain of a turn. Think of the construction of the knot, when putting the tag through the loops, it actually starts off going between the two lines, its not obvious because the big loop cause the two mainlines to be separate. I Hope this makes sense.

[Trevour]

My opinion on some of the questions, a uni will get stronger with additional turns, but not a fig8. This is because I reckon the knots owe their strength to different reasons. The uni basically works like a compressed bimini, where two lines are basically 'crimped' together by the turns going around them. When these knots fail, they often break just outside the knot, because the turns become too tight, strangling the mainline, and preventing it from stretching normally. More turns spreads the load, and reduces the tention each turn is under. A fig 8 reduces the tention in a different way. It would be interesting to have a discussion on the science of knots and why some do better than others.  I believe the strongest knots combine the methods in a fig8 and a uni. In braid try doing a twenty turn bimini, instead of half hitches just pass the tag between the loop lines, then do another twenty turn bimini, I l like going in the oppostie direction to the 1st bimini. Again pass the tag between the loop arms, and then another bimini, until there are 5 biminis on top of each other, then end with half hitches as usual. 1st bimini must be soft, and gradually they get tighter, eventually ending with tight compressed biminis. If anyone can understand what Im saying perhaps I can find someone to agree with me that this is a 100% loop, stronger than a stitched loop. All this is just my opinion, not proven fact.

[DonCouzens]

Hi on my medium setup I have been using the Bimini tied into 30lb DNA and then using the loop to tie a Yucatan onto a 0.8mm mono leader, works extremely well, but under max pressure, trying to bully a black steenbras out of his reef the Bimini seems to cut through the nylon leader. I suck at the FG and in medium tackle knot size is not crucial, Im after strength as I also do shore based jigging, still chasing yellowtail.
Any advice would be appreciated

[REEFMAN]

Don, joining braid to leader/mono is quite simple, without needing to do a Bimini even. A 7 turn Uni in the doubled braid to a 3 loop Fig 8 in the Mono is bullet proof. This is the join that Craig Thomassen uses as his go to knot.

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