[jfranta]

We have done, and continue to do UV testing on Dynex Dux (Heat Stretched/ Work Hardened Dyneema). Since we use and promote this for standing rigging this is very important to us. Dyneema fibers are the best synthetic fibers for UV resistance. We have enough data to recommend a 5-8 year replacement interval in the tropics. The data is still coming in and I believe that we will end up recommending an 8 year replacement interval for standing rigging. All this is for uncovered Dynex Dux that is/was initially treated with a Urethane Coating to help with friction and UV resistance.
Keep in mind that most steel manufacturers recommend an 8 year replacement interval for salt water boats.

The mechanism for UV damage on dyneema is such that the line experiences some external UV damage and then becomes somewhat opague for UV Rays so the damage rate diminishes considerably.

Also, this is based on the fact that we size the line for Stretch and Creep (not breaking strength). This type of sizing always ends up with line that is 2-5 times stronger than 1x19 spec'd for the same application. So you have a considerable factor of safety for strength.

John Franta, Colligo Marine