Some info that hopefully will assist you rslifkin:
Nylon has more stretch than polyester, making it more prone to chafe, dependent on loads (as described below):
- When loaded at 20% of Breaking strength: 3strand Nylon will stretch ~10%,
8 Polyester ~3% (Source: Samson
- Polyester line is as much as ten times better than nylon in dealing with chafe (Source: Yale Ropes). Snatching and wandering up and back from the anchor
in a gale will increase chafe at the rub points due to this greater stretch of nylon, as the nylon is moving back and forth more under loads. This is more a factor on larger boats and when longer lengths of nylon are deployed.
You can deal with the reduced elasticity of polyester line, and the resulting lower energy absorbing capacity, by simply veering more line (Steve Dashew). However, getting the right balance of load absorption from the lengths of 8 plait polyester deployed and it's diameter/breaking strength is a consideration, especially when in tight anchorages
. Could you use a rope snubber (of greater stretch) with the primary rope rhode..how will the rope snubber rolling hitch tie, hold and untie on the primary rope?
Nylon is more prone to abrasion than polyester when wet, losing up to 50% of its abrasions resistance when wet (Source: New England
Nylon 3 strand can cockle (open up the lay of the strands) under rotational twists of veering on anchor
. This cannot happen with 8 plait polyester, as it doesn't matter which way the rope is twisted, it only tightens the lay (Source Jimmy Green).
Arguably the best 8 plait polyester is made in Italy
by LIROS. It is branded as LIROS Squareline PES - Octoplait. Like you, hard to get in my country (Australia). Can be purchased and shipped from Jimmy Green in the UK.
Better to match anchor components by using minimum breaking load (MBL), as working load limit (WLL) is derived by a particular safety
factor (SF) applied by the manufacturer....commonly 5:1 for rope (i.e. WLL = MBL / SF).