Synthetic, Dynice Dux rigging, noise problems

[Nauticatarcher]

Hi, I just recently re rigged my Islander Freeport 36 with Dynice Dux, swapped out 1/4" SS for 8mm Dux, very happy with result and no issues so far except one, when sitting at anchor and the wind gets up rigging hums quite loudly, Im assuming its caused by the fact that Dux is slightly square shaped instead of round and this causes it to vibrate and harmonic, anybody else who's made the change noticed this?

[Jim Cate]

Warwick, our dyneema runners will vibrate in strong winds, but they are more or less round. Being only runners, at rest we can take the load off them and kill the humming. Harder to do with shrouds... but I don't really think the cross sectional shape will matter. The vibration is caused by vortex shedding, and that can occur with any shape.

Jim

[rgleason]

Try reducing or changing the period and tension by tying one or two lines around the shrouds and back to the mast.

[svHyLyte]

Originally Posted by Nauticatarcher

Hi, I just recently re rigged my Islander Freeport 36 with Dynice Dux, swapped out 1/4" SS for 8mm Dux, very happy with result and no issues so far except one, when sitting at anchor and the wind gets up rigging hums quite loudly, Im assuming its caused by the fact that Dux is slightly square shaped instead of round and this causes it to vibrate and harmonic, anybody else who's made the change noticed this?

Not uncommon--akin to a Wind Harp. Adding a damper can reduce the problem somewhat. As previously noted, try some damping lines--preferably shock-cord--back to the mast.

[mickeyelam]

I don't know what effect this may have on the strength of the rigging but you could try putting a twist into the lines that hum; basically, slacken and free one end then twist it about its own axis one or two times. I've found this trick to work when securing loads to truck/trailer beds for transport over roads.

Once again, I'm not sure what impact on the strength of the rigging this might have but I wouldn't expect it to be any real impact.

[Stumble]

You just have an unfortunate harmonic with the wind speed, and vortex shedding. Mine do this at about 15kn, but only upwind... Slightly tensioning them, or easing them,, or pulling them with a bit of bungie. Pretty much anything that changes the natural frequency of the line.