Do you double wrap?

There a many different ways to secure your slackline webbing.  A common method is to use a static lock created by passing a bite of webbing through a closed loop and securing it.  For instructions on static locker methods see the how to single wrap static locker and double wrap static locker.

Hypothesis:

The strength of webbing in a bend or a bite will be reduced.  The double wrap line locker increases the bend radius and reduced the pitching force in the knot.

Materials:

• 4 x 3m pieces of Skypilot Nylon Webbing
• 4 x 3 1/4 T 5/8″ Steel Shackle
• Certified Break Test Machine

Procedure:

Break test Method – Secure the webbing to be tested using the Static Lock Method below.  A constantly increasing force will be applied until the webbing fails.

Test #1 – Control Test – Perform a break test of a piece of webbing with double wrap static locker on both ends.

Test #2 – Control Test 2 – Perform a break test of a piece of webbing with double wrap static locker on both ends.

Test #3 – Single Wrap 3 – Perform a break test of a piece of webbing with double wrap static locker on one ends and a single wrap on the other.

Test #4 – Single Wrap 4 – Perform a break test of a piece of webbing with double wrap static locker on one ends and a single wrap on the other.

Data Collection:

Single Wrap Break Test Read-out

Analysis:

Control Tests – As expected the ‘control tests’ webbing broke inside the double wrapped static locker at about 80% of the webbing MBS. 

Single Wrap Tests – As expected the webbing secured using a single wrap method broke inside the single wrap at roughly 70% the webbing MBS.

Conclusion:

A double-wrapped static locker retains more of the webbing’s breaking strength at roughly 80% whereas the single-wrapped method retains 70%.  There are other methods of securing the webbing that retains more of the webbing strength.  More test will be performed on other lock-off methods.