*** Dyneema problems ***

gminkovsky · Post by **gminkovsky** » Wed 12 Jun 24, 18:25

: 2 dyneema lines

: dyneema deconstructed

I wrote years ago about Dyneema failure in my main halyard. Then a few years later I wrote about another Dyneema failure in my board downhaul. I wasn't sure what the cause was and speculated that it may have been related to some chafe and/or compression loads.

Now I had 2 more sudden breaks in Dyneema line. Look at the attached pictures.

One picture shows 2 different color Dyneema 8 mm lines with break. The other picture shows detailed construction of this line:

outer braided polyester cover
inner braided polyester cover
braided Dyneema core
1 strand of the braid pulled out

The inner core feels and looks like strands of cotton ball. The first few centimeters of core on both sides of the break have ZERO strength. They can be torn apart with fingers. They are as strong as a cotton ball. I also separated a piece of the line at the opposite end away from the break. The core is noticeably stronger there.

I brought these 2 failed lines to my rigger. He was APPALLED at the extreme poor quality of this rope. He agreed with me that the strength of the rope is in the cover (the 2 polyester covers). Once the cover is compromised, this rope breaks. He did verify that the 2 covers are polyester and the core is in fact Dyneema.

This Dyneema is absolute garbage. He advised my to immediately change all lines that are made of this rope.

On my boat this rope is used on:
main halyard
board up/down
both reefing lines
backstays
swing line
genoa furler
bowsprit tack line.

My boat was made in 2003. I don't know if the same rope was used in previous and later years.

I advise all of you to carefully examine all Dyneema lines and immediately replace any line with even minor chafing if your Dyneema is constructed the same as mine.

I am switching to New England Ropes Endura Braid 8mm (5/16").