Synthetic rigging properties?

Discussion in 'Sailboats' started by Gashmore, Sep 2, 2008.

  1. jfranta
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    jfranta Junior Member

    Sorry, but it is already on hundreds of boats as shrouds. You obviously haven't heard of it. Its also been used in the fishing industry for over 5 years now. There is some history. It seems to work pretty well.

    Common now, Do you really believe using Dynex Dux in this fashion is more dangerous than a swaged fitting? As an engineer, with some understanding of corrosion and swage designs, imo, it is not. Enough with all of the inflammatory remarks. Clearly you do not understand UHMWPE or you would know the lengths of creep or UV problems you have to get to to get a catastrophic failure, with clear visible indicators and breaking strength factors of safety of 5 or more. Unlike Swage fittings with no visible indicators.

    I mentioned the decrease in ductility before... along with many other details we seem to be going around and around about.

    Again, Dynex Dux has its limitations but can be used if these are understood. It is different and demands to be thought of differently.

    Step out of your box a little, Leanardo would be proud...
     
  2. RHough
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    RHough Retro Dude

    Show me some engineering data, not marketing hype. I've around boats for long enough to know that 1,000 of boats use the wrong materials in the wrong way. I know how much maintenance sailors don't do. I know how poorly most rigs are tuned.

    I ask questions, you return and repeat the same marketing crap.

    Swag fittings are Mil Spec items when I do them. I cannot say how others do them. The swag termination process is well documented and swaged wire rope data can be used for engineering. So yes, home spliced rope rigging is much more dangerous than swaged fittings done to the proper spec. I have yet to see a properly swaged fitting fail within the normal service life of the wire it is attached to. (assuming the fitting and the wire also meet Mil Specs) If we start seeing swag fittings come out of Asia, all bets are off. Arco, Hayne, and Ronstan all make proper fittings ... there is an engineering standard for all of this stuff. Where is the engineering standard for what you sell?

    Here we have a Civil Engineer, asking some dead simple engineering questions about UHMWPE and he is asking everywhere he can.

    You claim to be an engineer, yet you cannot or will not answer his questions. You don't even understand that a decrease in ductility might make Dynex *WORSE* in a rigging application. You seem to think that a lack of elasticity that breaks winches is a good thing. Did you ever stop and think that shock loading fittings designed for the ductile properties of steel might fail also?

    One reason that the engineering data is not available is because UHMWPE rope was never intended for that use.

    You are the one that has to provide the hard data so this rope can be compared. Until you do, you are a snake oil salesman. You have hitched your wagon to rope rigging bits and are selling it to people that don't know better.

    Just answer the questions, and stop defending a product that you know so little about. You are the one making the claims you cannot back up, you are the one with the homey junk science on your website. You have to prove your claims.

    If you haven't already, why not get the manufacturer involved? Get them to post some engineering data on their wonder rope? Get them to make a public statement that they approve the use of their product for standing rigging. Protect yourself from lawsuits, let them assume the liability.

    I've said I'm willing to be convinced, but the more you weave and dodge simple questions, the less convincing you are.

    For starters, since I know so little. Please explain how the fibre gets its strength and why it creeps. ;)

    And one last thing, who do you sell lifeline terminators to? Are rope lifelines legal?
     
  3. jfranta
    Joined: Sep 2008
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    jfranta Junior Member

    You really are crossing the line here. This is supposed to be a professional forum, name calling come on! As we do with all of our customers, we are working with Glenn to provide him with the answers he needs. Another false statement of yours. We have nothing to hide. If you take a close look at the info on our website you will see it is engineering information along with references. If you look around you will see that we provide more data than most and we will continue to populate our site with data. Most of your questions can be answered by my previous posts. The others can be found by doing some searching on the web, polymers,etc. I can't give you an engineering education in this forum. How can you claim I do not understand ductility from our conversation? explain that to me? These are rhetorical questions as your unprofessionalism disqualifies you from further conversation with me and probably violates the rules of this forum. If you don't like our products or Hampidjan's, don't buy them.

    John Franta, Colligo Marine.
     
  4. RHough
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    RHough Retro Dude

    All we ask is for simple engineering data.

    Some of us take the safety of our customers very seriously and would never recommend a rigging solution that is not backed by engineering data.

    Apparently, your standards are not the same as mine.

    How many times do I have to say that I *WANT* to be able to offer better solutions? I just require a bit more than 100's of others (that don't know the data) have used it.

    As far as professionalism goes ... You are the one claiming to be an engineer; I'm just a lowly rigger. ;)

    You sell lifeline terminations for synthetic lifelines.

    Do they comply with ISO 15085?

    They do not comply with Offshore Racing Regulations:

    So here is a black and white example of a company selling a product for a boat that would not be legal for a racing sailboat. CFR46 that has the regulations for commercial vessels requires railings, not lifelines.

    Dynex Dux cannot be used for racing boats as lifelines, and it cannot be used on commercial vessels. What does that leave? CS Johnson also sells a line of lifeline hardware that allows the use of synthetic rope to replace steel wire. When a customer asks about it, I show them the offshore regs.

    Why would anyone sell a lifeline system to a customer that does not meet a published standard?

    I have searched for fibre products that were designed for standing rigging applications and found several. NONE of them are exposed braid construction.

    If you have a cite that shows differently, I would like to see it and learn.

    On UHMWPE:

    In service braided rope flexes and stresses the fibres. Over time the stresses in Dyneema tend to equalize. More highly stressed filaments in each yarn creeps more until the stresses are the same as the other filaments. As loads change (there is no such thing as a static load in rigging outside a test lab) the long chain molecules that give UHMWPE its strength start to break down. The rope becomes weaker with each cycle. This is a fact. There is test data to support it.

    I have not seen the results of test on braided rope that cycles the load while keeping the rope under tension. One reason is that braided construction was not designed for that application. Again ... fibre cable that is designed for applications like standing rigging is parallel strand inside a weather cover.

    IMO it is insane to even consider using unsealed braid as standing rigging. It might be possible to use braid if the entire shroud (including the splice) were then sealed to protect the fibre from chafe and contamination that accelerate the breakdown of the long molecular chains the rope needs for it's strength.

    So, either provide data to show that my concerns are unfounded, or go away.
     
  5. Gashmore
    Joined: Feb 2008
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    Gashmore Junior Member

    Dynex Dux First impressions

    Received my 9mm sample of Dynex Dux yesterday but will be spending the next few days casting the 4,700 lb keel fin and mating it to the bulb so it will be next weekend before I can do any testing.

    First impressions though is that this is NOT your fathers rope! Examined the braid in comparison to a length of 9mm Amsteel Blue from Sampson. Amsteel is a 12 strand braid Dyneema SK75 same as the Dynex Dux but beyond that the similarities end. First off it the Dynex is a lot harder and the angle of the braid is much more acute. About like Amsteel under an extreme load. Under a 20x microscope the fiber looks similar but there is less twist in the Dynex Dux yarns.

    I hope to start my initial pull test next weekend and will report back.

    Glenn
     
  6. RHough
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    RHough Retro Dude

    Great news!

    If you have time to set the Amsteel up under tension for a few hours, could you compare the braid angle and the apparent twist in the yarns?

    This 'construction set' must be taken out before the elastic properties of the fibre can be evaluated.

    It has been my experience with HM rope that the construction set takes time to work it's way out of the rope. Once set, the length is relatively stable for a few hours. If the rope is then left untensioned for a day or two, it has to be tensioned again to it's stable dimension.

    Dyneema/Spectra Halyards are prime offenders. If they are not "set" before they are put into service at the start of a race or cruise, they will not hold an adjustment even at loads that are not high enough to cause very much creep.

    I am really looking forward to the results of your tests!
     
  7. RHough
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    RHough Retro Dude

    I've attached the article.

    Here is what they say about splices:

    This is exactly what I said when I questioned the locked Brummel splice shown for Dynex Dux. :p
     

    Attached Files:

  8. RHough
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    RHough Retro Dude

    Gashmore called my attention to the splicing instructions on the Colligo site.

    They call for a 72 X bury. I have sent an email to Colligo to retract my comments about the splicing instructions. I did not save a copy of the instructions that I reacted to. If they have always called for a 72 X bury, my comments were out of line. At the time I made that comment I was certain that they did not.

    Bottom line is that the Colligo Splice is correct now.

    With the recent development that Dyneema/Spectra is now Legal for Offshore Racing, I would like to publicly state that the Colligo terminations look to be some of the best I have seen.

    I will be converting by boat to use Dynex Dux and Colligo terminators this year.

    I still have reservations for standing rigging, but I have to say that some of my concerns have been addressed positively.

    Randy
     
  9. gonzo
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    gonzo Senior Member

    Manila and cotton kept boats and ships sailing for centuries. A racing rule is not the last answer to all fibers and systems.
     
  10. RHough
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    RHough Retro Dude

    True.

    However from a retail standpoint, when liability is involved it would have been foolish to sell a synthetic lifeline in the past. Now there is documentation for their use and I am very happy to be able to back up a recommendation of Dyneema or Spectra lifelines with this information.

    Without it, how do you think a wrongful death suit would go if a Dyneema lifeline broke? :(

    I've dealt with enough insurance companies and surveyors to know better to put stuff on boats that would leave me liable. I'm not saying it is right, only that it is a part of doing business in the US and Canada. If you can cite an authority and show that your usage conforms to a published standard, you are pretty safe, if you cannot ... it can be ugly.

    R
     
  11. Paul B

    Paul B Previous Member

    You better be careful here.

    If the sailing instructions are not changed for the event you are sailing in (by invoking Rule 86) then you cannot have anything except wire lifelines. I think most people running races are going to err on the prudent side and not change the instructions, as that puts the liability on them.
     
  12. RHough
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    RHough Retro Dude

    I agree sort of ... :)

    The ability to make the change has been there ... Rule 49.2

    What has changed is:
    PORTSMOUTH, RI (January 22, 2010) – Composite lifelines are being used by sailors more frequently, especially in around-the-buoy racing. In the 2010-2011 edition of the ISAF Offshore Special Regulations, Dyneema® is now an approved lifeline material for offshore racing. There have been concerns that the offshore regulations were in conflict with the racing rules regarding lifeline materials.

    Prior to this there was no authority to cite. AFAIK.

    All that the Si's have to say is Rule 49.2 is modified to change "wire" to "approved lifeline material" as defined in the ISAF Offshore Regulations.

    I think (hope) there will be very little resistance to this change.

    For non-racers and for the purposes of survey, I used to recommend bare 1x19 for lifelines based on the Offshore Regs. Now I can recomend Dyneema also. Anything to get those disasters waiting to happen PVC coated "lifelines" off the boats. I've seen too many predicable failures to want to see people use coated wire.

    R
     
  13. Paul B

    Paul B Previous Member

    Just be careful you don't end up with some pretty angry customers when they get chucked from every race they enter where the authority has not changed the SIs.


    Agreed, no one should use coated wire for lifelines. I wonder if in 2 years you will be commenting on the "disaster waiting to happen" dyneema lifelines? I don't know that we have enough data to make a determination on whether mom and pop programs should be looking at this yet.
     
  14. RHough
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    RHough Retro Dude

    I'll ask the racers to talk to the local authority before making the change (of course).

    This is from the US Sailing article:
    Chafe protection
    Spectra® is one of the most chafe resistant fibers available. So, the single best way to protect against chafe is simply to use a larger diameter Spectra® single braid line. This will be both extremely chafe resistant and easy to inspect. When Spectra® chafes it shows quite visible fuzz on its surface.

    UV resistance
    Spectra® is one of the most UV resistant fibers. The loss of strength depends on the line’s specific construction, but generally the sort of small diameter line used for lifelines will lose about 15% of their tensile strength (=85% of original tensile strength) after 6 months of continuous strong sun exposure (testing in Mexico and Arizona) and at 5 years will retain about 60% of its tensile strength.

    Line size should be selected to compensate for this UV reduction in tensile strength. 3/16” stainless wire has a tensile strength around 3800lbs, while 3/16” Spectra® single braid has tensile strength around 5,800lbs. So, picking the same size Spectra® as wire will roughly allow for equal strength after 5 years of intense UV.

    Selling points for me are that Mom and Pop can see chafe if it is a problem and that there is a history out to 5 years. The OD of the coated lines is 1/4" or so, 6mm or 1/4 Spectra will be much stronger than the wire it replaces for many more than 5 years. The end fittings are reusable and I would be happy to walk a customer through the splice if the want to "DIY". When the cost of the swagged hardware and labour are included I think that a Spectra system becomes price competitive as a replacement, it becomes more cost effective the second time around.

    I don't think the market is very large yet, but it is large enough that more than one supplier can provide fittings.

    On a personal note, I find the difference in diameter between coated wire and bare 3/16 1x19 to be a comfort factor. The "feel" of cold wire compared to coated wire also took some time to get used to. Bad me, I use the lifelines in the cockpit for a backrest ... comfort is an issue. :)

    The main thing is that I can discuss this option with people without feeling I have to advise them of the conflict with the OR ... more choices are better IMO.

    Think this is progress ...
     

  15. Paul B

    Paul B Previous Member

    The same mom and pop who don't see the rust running along the outside of their coated wire?


    This might be a good solution, but it seems to me if it was a Panacea the ORC would not have written the regs like they did.
     
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