Dyneema v Amsteel Blue

[RedLine 0]

Hi wanted a couple of runners sorted in 6mm Dynema before I stand up my new Rig, but could only locally source something similar to Amsteel blue, which I bought (from Cookes/Bridon) and have tucked in a couple of double Brummel splices.

 

Is there any difference between the usual grey Dyneema you see everywhere and this light blue stuff used by Fisho's and 4WD'rs etc. And is it ok for runners. My thoughts are I guess it could be less UV stable? Haven't turned up anything much else with a google.

 

Cheers

Stu

[Guest]

Bridon sold you Dynamica, especially if it's harder and stiffer as Dynamica is generally a heat set version where Amsteel Blue isn't. For runners or any lines that don't need to go around corners the heat set versions are fine but they will break down a lot faster if they run through blocks so us the non-heat set options there. The heat set has big flex fatigue resistance issues the non-heat set doesn't.

 

Ocean 12 - usually grey

Ocean 12HS - usually grey with a red tracer

Amsteel Blue - usually blue but has 3 (?) other options

Dynamica - light blue

Dynex - grey

Dynes Dux - orange

SuperRound - many

Dynaforce - many

Light75 - plain white

and many more

 

Are all brand names for ropes made out of Royal DSM's 'Dyneema' fiber.

 

All of the above are most commonly found in what is called SK75 grade (hence why often you'll see '75' behind the name) but there are a few SK78 and now some like Dynaforce90 which uses SK90 grade fibers. There is also a few hanging in with Sk60 but that grade has pretty much had it's day now. The bigger the SK number the stronger it is and the less creep it has..... also the bigger the wallet will be required but as more 90 comes on stream the prices will drop, they did when 75 became common a few years back. SK78 will pop up a lot for a wee while then go away, they have already stopped making the base fibre in leiu of going hard with SK90 instead.

 

The colour makes no difference at all. That is just a colour and generally means feck all (you can get green Amsteel Blue for example but it was only available in blue until knot long ago). I know a place (cough cough) that has 7 or 8 colours and even makes it's own like 'Kermit', which gosh shock horror isn't anything like 'Miss Piggy Pink'. The colour is contained in a 'coating' that is designed to help hold the fibres nicely together (they are super fine and can go fur ball fast) and give the rope better UV, abrasion and recognition qualities. The coating can vary a bit so some can make the rope seem stiff but if you play with it a bit it'll go all floppy, you know how that goes lads

 

Also much as some manufacturers use load numbers in interesting manners or do or don't include terminations, all the rope are made with the same fibre from the same manufacturer so if equal in size will all break at around the same load. There will be some differences due to lay angles and things like that but it won't be massive.

 

So the question of Dyneema V Amsteel Blue doesn't really exist seeing one is made of the other.

[RedLine 0]

Thanks KM

 

According to the cookes/bridon web site its SK75, so should be fine, will terminate in an eye each end, then a 4:1 at the deck end of things. Thought you would likely know if it was likely to be different or knot! So will make use of the 30 odd M of the stuff I just bought. Grey would have looked better, but hey blue will do.

 

Hope to be standing up the new carbon rig in a day or twos' time If I can get the rigger back to cut some wire stays the right length. Cant remember if its in the class rules or not about using fibre rigging all round for a 930?? Will mostly be using Dyform with exception of runners deflectors.

 

Cheers

 

Stu

[sow1ld 2]

Where using the 8mm sk75 blue stuff from bridon on our backstay from the ram to the insulator for the ssb. It's quiet stiff to work with and we've done a bremul? eye splice at each end.

It seems to be holding up fine (masthead ior boat 36ft) with 4000psi on the ram approx 2.5ton.. it did stretch a little bit in the beginning but has settled down now after I stitched whipped the ends. My only concern is uv and how it will stand upto that. I was thinking of putting a jacket over it

[Guest]

A Brummell is one form of a splice that can form eyes, thimbles or other fittings. It's a word often used wrongly as most Brummel splices aren't.

 

Yeap it'll stretch a bit at the start while you pack splices and get the manufacturing slop out but then it should stabilise.

 

UV shouldn't be too much of an issue as dyneema will act like alloy and the top layer will 'oxidise' giving the rope a sort of sunscreen. That's why it's best knot to rub dyneemas too much if you have the chance. Yes covering it will also help it but you could also re-coat the rope after 4-5 years if you liked.

 

Feck it's hot in myoat. The last of the inside grinding will take an hour and Ya Fecking Hoo!!! that's done and we can start attaching sh*t to the brand new super sexy main bulkhead.

[otto 31]

A Brummell is one form of a splice that can form eyes, thimbles or other fittings. It's a word often used wrongly as most Brummel splices aren't.

 

Yeap it'll stretch a bit at the start while you pack splices and get the manufacturing slop out but then it should stabilise.

 

UV shouldn't be too much of an issue as dyneema will act like alloy and the top layer will 'oxidise' giving the rope a sort of sunscreen. That's why it's best knot to rub dyneemas too much if you have the chance. Yes covering it will also help it but you could also re-coat the rope after 4-5 years if you liked.

 

Feck it's hot in myoat. The last of the inside grinding will take an hour and Ya Fecking Hoo!!! that's done and we can start attaching sh*t to the brand new super sexy main bulkhead.

 

WTF I've just left for you to do some work on the boat and you're on here ???

[wheels 543]

WTF :wtf: I've just left for you to do some work on the boat and you're on here ???

[Kiteroa 8]

My 2c is that only the very top of the line 'Dynex' products (SK90 etc) are worth entertaining for runners. If you're trying to tension a forestay (reduce sag) you need a really stiff cable to get any meaningful performance gain. It's not very effective trying to pull against a stiff wire forestay with a competitively stretchy dynex runner. I've always gone for a very shallow braid vectran or a K49 Kevlar product. Over waves, a dynex runner will usually let the rig wobble and the jib luff pump. It's far less an issue with the aramid, From memory I think Vectran stretch is about half that of a Dynex SK75 fibre. But the aramids to suffer from UV and salt exposure, which is not such a problem with the dynex.

[Bill 0]

"A Brummell is one form of a splice that can form eyes, thimbles or other fittings. It's a word often used wrongly as most Brummel splices aren't."

 

KM, not sure what you mean here. I use the Brummel as described in Brion Toss's Rigger's Apprentice as a means of locking the eye when it's not under load. My understanding it that it adds no strength to the splice, this is determined by the length of the bury. Is this incorrect and if so, please elaborate.

[wheels 543]

My 2c is that only the very top of the line 'Dynex' products (SK90 etc) are worth entertaining for runners. If you're trying to tension a forestay (reduce sag) you need a really stiff cable to get any meaningful performance gain. It's not very effective trying to pull against a stiff wire forestay with a competitively stretchy dynex runner.

It's not so much the material it is made from, but in how it is made, or more accurately, how it is woven. This is where we see the big differences between manufacturers. For instance, not all sizes are the same. One makers 10mm can be quite different to another's. There are different weave patterns and numbers of strands that make up that weave. The greater the angle in the weave, the more stretch that occurs before the fibres finally "take up". Hence why there are prestretched lines and heatset lines. SK75 is still going to be a strong enough fibre and in the right design, will perform better than wire.

Also realize that the higher the number, eg 75 or 90, means the denser the molecular weight of the plastic that fibre is made from. So it is heavier and can be stiffer depending on the way it has been made.

If you guys want splices in these lines, I seriously suggest you bring it into the boys at CRA. I have consistently tested their splices to destruction and the line always breaks before the splice fails.

[Kiteroa 8]

The Donaghy's site offers some valid comparisons for a range of fibre.

 

From what I can see, the UHMPE (Dynex) products range in elongation at break from 5% for your regular Dyneema, down close to 2% for the rolls royce SK90 products. Off the shelf Challenge braid Vectran has an elongation at break characteristic quite similar to the very best of the SK90 products, but with zero creep, which has proved to be the achilles heel of the UHMPE products. After stretch, creep is probably the most important characteristic for a high static tension line like a runner stay. So for me, Vectran is a no brainer if you want effective running backstays.

 

Dynex is great in a backstay application if you want the line to last for a long time, but not perform so well. (kind of like a dacron sail) The vectran should be replaced every couple of years as it has UV and salt issues, however during that time it will do the job very well and you'll notice the difference in performance (like a nice kevlar racing sail).

 

https://www.donaghys.com/file_uploads/brochures/Marine_Brochure_Website_secure.pdf

[wheels 543]

Any lines sensitive to UV etc can be protected by a special Polyurathane coating we have. It's available in many colours.

[Guest]

Dynex is a name of a version made in Iceland by a mob whose name I can't spell. Donaghys version is called Ocean12 and Ocean12HS. There are many as most rope makers have their own version. Dynex is an older name so pops up a lot as does Amsteel but that's because they make so frecking much of it and in massive sizes. 1000's of tonnes break load anyone?

 

"A Brummell is one form of a splice that can form eyes, thimbles or other fittings. It's a word often used wrongly as most Brummel splices aren't."

 

KM, not sure what you mean here. I use the Brummel as described in Brion Toss's Rigger's Apprentice as a means of locking the eye when it's not under load. My understanding it that it adds no strength to the splice, this is determined by the length of the bury. Is this incorrect and if so, please elaborate.

I was just musing Brummel seems to be a go to default word for 12 strand splices, a bit like Dynex is for Dyneema and DIN is for anchor chain. I see lots of Brummel splices that aren't, the majority in fact.

 

You're correct on all of that Bill. It is a locking splice, it doesn't add strength in fact it detracts a tiny smidgen and the bury is where it's all at. While you can use less depending on application and the specific form of rope being used, if in any doubt stick with 50 times Diameter and you'll be good to go.