To thimble or not to thimble – that is the question.
First, a little bit of info on D/d ratios.
There is a common belief that a synthetic rope eye termination should possess a diameter D/d ratio in the 6-8 range. Most synthetic winch ropes come with metal thimbles providing this ratio when new. The trouble is that the metal thimbles eventually yield and collapse onto the retaining pin, thus reducing the D/d ratio considerably.
Is this so bad? What happens to synthetic rope strength when the D/d ratio is reduced?
Luckily for us off roaders, many technical papers have been written on this by rope manufacturers and cordage experts and corresponding tests have been completed. Even when a single leg rope eye is pulled against a D/d of 1 (3/8 rope eye pulled against a 3/8 pin), the rope still retains almost all of its original strength.
Why is this?
It’s because you have the load of the pin being carried by two legs of the rope, similar to basket loading a synthetic sling. In fact, the testing standard for pull testing synthetic rope single legs is to use a shear pin in the (1.5 – 2) X d.
So what’s the bottom line, and what does this mean to us off roaders?
It means that if your rope retaining pin is smooth, and at least as big as the rope diameter or greater, you can run a soft thimble-less eye on the end of your rope and lose little to no breaking strength. We just released a rope spools with a D/d ratio of 2.6 for those who would like to run soft eyes on the Factor 55 products
ROPE SPOOL SIZE CHART:
XTV ROPE SPOOL: ProLink XTV
STANDARD SIZE ROPE SPOOL: ProLink, FlatLink, FlatLink E, Bridle, and UltraHook
XXL ROPE SPOOL: ProLink XXL
MADE IN USA
NOTE: If you currently have a metal thimble on the end of your synthetic rope, ROPE SPLICING IS REQUIRED
NOTE: FlatLink XXL has its own rope spool specific to that product.