HM rigging

[Gary]

Ok...I've got the bug. My first question. Is Dynex Dux and Amsteel blue the same thing? Seems the Amsteel is quit a bit less expensive. Going to be re-rigging a Bristol Channel Cutter.

oh cool...I'll be the first on my block!

Gary

[benz]

Hi Gary,

Amsteel blue (or any color) is not the same as Dynex Dux. Amsteel is given to 'Molecular creep' which just means it will get longer as time goes by if it is under tension, as it will be in shrouds and stays. So you would be forever tuning your rig, and occasionally re-splicing the Amsteel. Not practical.
But there is no shortage of threads in this forum (look in the archives), discussing various HM lines suitable for rigging.
Incidentally, I'm building a CG 31, very similar to a BCC, and will be rigging it with Vectran.
Good luck,
Ben

[Gary]

Thanks Ben,
I was under the impression that the Amsteel "blue" was a newer heat treated version of the original Amsteel. (not actually refer to the color)

Why did you choose the Vectran?

Saw my first CG31 just last week. Sailed in here to St. Thomas. What a great looking boat. It was owner built with the cabin stopping at the mast. Man you will love her when your done! Good luck.
Gary

[Bob Pingel]

I believe that Amsteel Blue (the material, which I think only comes in blue) in SK75 (the actual fiber) and Amsteel is SK60.

Dux is SK75 that is prestretched and heat treated to reduce creep and elasticity.

I have heard rumor that Marlow is creating a heat treated Spectra/Dyneema.

Bob Pingel

[Gary]

Here is the reason for my question.
Defender carries the Amsteel Blue (they have a silver/gray custom color they carry). "AmSteel-Blue is an upgrade design from Original AmSteel and it offers superior strength in the smaller sizes" and yes it is made out of Dyneema® SK-75 fiber. On Samsons site they rate the elastic elongation at 0.7% at 20% load.
Over at Colligo they are asking $4.84/ft for the 9mm Dynex Dux. While at Defender they are asking $1.99/ft for the 5/16 (closer to 8mm) Thats a HUGE savings!

My rig is 5/16 316 with wire splicing (Lyle's specs call for 9/32 and 1/4). This will take out over 65lbs aloft....how sweet it is!

Gary (and my trusty calculator)

[Jack]

Originally Posted by Gary

Here is the reason for my question.
Defender carries the Amsteel Blue (they have a silver/gray custom color they carry). "AmSteel-Blue is an upgrade design from Original AmSteel and it offers superior strength in the smaller sizes" and yes it is made out of Dyneema® SK-75 fiber. On Samsons site they rate the elastic elongation at 0.7% at 20% load.
Over at Colligo they are asking $4.84/ft for the 9mm Dynex Dux. While at Defender they are asking $1.99/ft for the 5/16 (closer to 8mm) Thats a HUGE savings!

My rig is 5/16 316 with wire splicing (Lyle's specs call for 9/32 and 1/4). This will take out over 65lbs aloft....how sweet it is!

Gary (and my trusty calculator)

Gary, what Amsteel is referring to is they upgraded from SK-60 Dyneema to SK-75 Dyneema. It also sold as Spectra and a few other brand names. It is all SK-60 or SK-75. I know the Blue is SK-75 and the SK-60 is Grey from Samson.

One way to compare is to take the strength charts and compare. Off the top of my head I think 7mm SK-75 is 10k breaking strength. Looking at Samsons chart I see they are using #8600 breaking strength on 1/4". If you move up to 5/16" you get 13,700 breaking strength. The 7mm Dux is #15,000 Breaking strength. Does not look like the same stuff.
I have seen some heated and stretched stuff from Marlow. It looks like the angle of the fibers are stretched out longer than the Dux. I am not an engineer but I believe if you lengthen the fibers to be more parallel you get more strength.

5/16" is very close to the 9mm Dux that will get you #26,500 breaking strengths. You can see it is not the same stuff. But Colligo will tell you you do not size for strength as much as you size for creep. Keep the static loads down to 10 or 20% of the working load and your creep is less than SS wire. As long as you are in the design phase drop John a note, he is very attentive to his customers.

Good luck with your project, sounds cool. I love BCC's.....:-)

http://www.samsonrope.com/index.cfm?...ope=192&inst=1