Dyneema has a slightly different molecular structure than Spectra and higher breaking strength in the larger diameters. It displays slightly better wear characteristics in heavy use areas, but has more elasticity than Honeywell’s Spectra 1000. This fiber is popular in Europe and is gaining popularity in the US.

Spectra is an amazing fiber that is very strong and durable. It has super low stretch, and is light enough to float. Spectra has the best fatigue life of any fiber. The only problem with Spectra is “creep”. Under steady high loads, Spectra will elongate very slowly. After a period of time, you might notice that your jib halyard now seems an inch looser. Using one size larger will greatly reduce creep, but it may still be noticeable. Spectra is the ultimate material for high fatigue and lightweight spinnaker halyards, guys & sheets. Spectra does not absorb moisture, which keeps it lighter on the boat.

Examples of cordage containing Dyneema: Amsteel Blue, Warpspeed, Superbraid, Ultrex, LOUPS.