The Importance of Splicing rather than using a Landlubbers Knot
Knots lower the strength of all ropes by at least 50%. This is because knots have a very high centre of curvature when the rope wraps around the same rope in a knot.
However, different braided ropes made out of different materials should use the most appropriate splice for the application.
Polyester and Nylon double braids should be spliced using a standard Polyester splice where the outer cover is fed back down the braided centre.
This is not acceptable for UHMWPE, Dyneema® fibre, Spectra and Vectran ropes or ropes that have a centre that carries most of the total load. (See splicing instruction.)
Single braids in all materials are best to use a Brummel splice where the tail and main rope are interlinked through each other to make a simple high strength splice. The tail is then tucked into the centre to finish the splice.
Nautilus Braids has the ability to carry out machine splicing when the rope is being made. This can only be done at one end. However, a machine splice is particularly effective as both the centre and the outer can be fed back down the centre of the rope and tapered to make a superior splice.
The Importance of Splicing – especially for braids made with UHMWPE Fibre
Nautilus Braids has installed a high spec strength tester for testing ropes up to 14 tonnes. There has been much knowledge gained as we can liberally test all our ropes. Much of this information we already know but the refinement gained has been great and we feel some of this should be shared with our customers because of the immense importance.
1. UHMWPE (Ultra High Molecular Weight Polyethylene) ropes get stronger as they are used up to a point (after some years of use) where they start to deteriorate. Typically, on an 8mm winch rope, the increase in strength with use may be as high as 800kg.
2. In the test standards, there are different tests – a cyclic test and a straight break test. Most braiding companies quote the cyclic test as their claimed strength.
3. Always use splicing for UHMWPE ropes. For single braids, it is best to use a Brummel splice with a long tapered tail (at least 400mm long is necessary). For double braids, it is best use a double braid UHMWPE eye splice.
4. While it is not so important due to the small amount of fibre stretch, polyester braids should also be spliced rather than knotted.
5. The tight bends in the rope when knotted create pressure points where the braid will fail. See the four different splicing techniques we recommend below:
1) Brummel Eye Splice
2) Non–stretch Core Double Braid Eye Splice
3) 100% Polyester or Nylon Double Braid Eye Splice
4) Multiplait Splice
The graph below illustrates the difference in strength of a non-stretch test sample with and without a knot tied in the rope.
Brummel Splice – For Single Braids
1. Pull end hard to roll “inside-out” at Mark A.
2. Now pass end through centre of rope at Mark B (in same direction as before).
3. Pull A all the way through the pull tight.
4. You now have points A&B rolled inside-out.
5. Now un-roll point A working rope up and through point A in direction shown.
6. Pull point B all the way through A.
7. Now un-roll Point B working short end up & through Point B in direction shown.
8. Pull short end up – while pulling the standing end down as shown.
9. Continue to close-up locked Brummel Splice.
10. Finally, bury tail into standing end.