At Colligo Marine
we have spent alot of time trying to understand the Dynex Dux and it's applications for standing rigging on Sailboats. We have rigged over a hundred Multihulls with rotating and fixed masts and many monohulls now including a 55 foot Schooner in Annapolis
with our hardware
and Dynex Dux.
If you are going to use Dynex Dux there are a few rules you need to be cognizant of:
1. You size the line for Creap and Stretch, not Breaking Strength like Steel
. For most Cruising applications the static loads will be low enough that you will not have a significant creep problem. There is a creep table for the smaller diameters available on our website to understand its use for your application. There is also a stretch table for similare usage. If your boat is currently rigged it is easy to compare your wire to the variuous sizes of Dynex Dux. If you size the line this way you will be at least twice as strong as the 1x19 wire you are replacing, giving you a significant safety
margin for any chafe issues you might have. Our Creep and Stretch testing has been veryfied by several outside sources now and is consistent.
2. Dynex Dux is not rope
as you know it, it has been Stretched in a steam oven
at elavated temperatures. This does a number of things to the Spun Polyethylene; It work hardens the material, which makes it stronger and much stiffer. It is the most chafe resistant line you can buy. It also virtually eliminates the constructional stretch and sets it so it does not loosen. This stiff line requires special end terminations with at least a 5/1 bending diameter to line diameter ratio, this is a recommendation of the line manufacturer, Hampidjan. I would ask you, Gary, to keep an eye on the inside diameter of the line as you wrap it around the Precourt hardware
to splice it. The Precourt hardware was designed for SK-75 and Aramids before Dux was even around and does not meet the 5/1 ratio, it is too small and much too small on the upper deadeyes. Watch the inner strands kink up as you splice the line and then do some research
on the web to find out what happens to Polyethylene when you kink it. With Dynex Dux you can easily cut the strength in half when kinking it. We have done alot of pull testing with Dynex Dux and when spliced correctly it always breaks at the bend around our line terminators. We are currently doing a UV study on Dux and pull testing line that has been UV aged, It also breaks at the bend where the only stress riser is, but at much less load than unaged line. We wil be posting
this UV degradation data on the web soon.
Using a smaller radius is no problem as long as you have a big safety factor in the line and change it often. This easy for trailerables that get inspected all the time and this is Precourt's target market. The problem is that inevitable UV damage will bring the breaking strength down continuously until you have a failure. A tight radius will significanlyt decrease the amount of time to that failure. For a large boat with fixed rigging that does not get inspected all the time it is very dangerous to use hardware that does not meet Hampidjan's 5/1 requirement.
Using our hardware with Dynex Dux, we can easliy now say 5 plus years in the sun uncovered and will be posting
our UV study reports and subsequent recomendations for all to see on the web. Any smaller Radius hardware is going to give you significantly less line life.
Gary, I think you should make it clear on your blog that you are using hardware that does not meet the line manufacturers reccomendation. Dynex Dux is new technology and its misuse and subsequent reports of failure can set this technology back for all of us. In additon, Precourt should be very clear to all that their hardware does not meet this requirement.
John Franta, Colligo Marine
Originally Posted by seacap
Synthetic rigging aka HM (high modules) rigging, Dynex Dux etc.
I'm taking the plunge and re-rigging my Bristol Channel Cutter with it.
so far there are number of good discussions here at:
Any Updates on Synthetic Rigging ?
I have started a blog at www.garyfelton.com/shanti/
to document the process, problems and hopefully joys of the new rig. You all are invited to the discussion on the blog or here on this thread. I think it is exciting new technology for enhancing the performance of anyones boat. Removing weight aloft is a great performance booster for any boat. On Shanti the weight savings will be around 70lbs! I have personal experience on a 86' ketch
that removed 1200lbs out of their rig by replacing the roller furler
mast with a carbon fiber unit. The performance difference was stunning! There is a rule
of thumb that goes for every pound you remove from aloft is like adding 10 pounds in your keel
(your mileage may very).
There are other advantages for cruisers also. Easily rigging and emergency
stay. No rust. No worry about stainless fatiguing. Easy do it yourself. The one big problem. if it is a problem, will be UV. So far this appears not to be a big problem. Of course down here in the Caribbean
I will be giving this area a good test.