Synthetic rigging properties?

[jfranta]

Not so, the PBO cable is sealed during manufacture. The replacement interval, is the classic, "lets test, and be very conservative" approach that has earned NavTec their reputation.


I have, I read every word I could find, before I posted about it. But in case I missed something I'll read it all again ... looking for hard engineering numbers.

What happens to the pre-stretch when the rope is worked? How does torturing the fibre during the splicing operation effect the rope? Does this statement ring a bell?

Has the pre-stretch been destroyed? Are all the fibres still aligned? Have any high stress points been introduced? Is the rope as strong as it was before?

Here is another statement:


Very true, because the untapered end of the bury creates a stress point, that is where the rope will fail. The Mobius Brummel does exactly that at the throat of the eye.


Careful what you ask for.
Work hardening:
"This leads to an increase in the yield strength of the material and a subsequent decrease in ductility."
"Ductility is the ability of a material to undergo large plastic deformations before fracture."

Are you saying that work hardening makes SK-75 less ductile? That it cannot stretch without breaking? That it is brittle?


Gosh, that makes me feel good. NavTec and Loos do the testing *before* they sell a rigging product. What you just said is that you have no idea how cyclic loads effects the rope, but you are selling parts to DIY boaters to rig their boats with it.


Brion is a good guy, I don't know that he has a formal engineering degree. No doubt he is a good rigger. I've seen the splices fail. These are professional splices, not the ones that amateurs make. Ask Brion how many splices an apprentice needs to make before they are good enough to sell to a customer.


I give you full marks for doing your homework, the terminators look great! I can see using them for several applications.


I say it again. I want to be convinced! It is just so easy to poke holes in the hype that I am very reluctant to take anything at face value. I think it would be wonderful to be able to go to a boat with a spool of rope, a bag of fittings, and a splicing kit and re-rig it. I much prefer working with rope over wire or rod.


I think you are dreaming. I don't think you understand the physical properties of UHMWPE.

One thing I know, you don't have enough engineering data on the rope to be able to recommend it for a mission critical application like standing rigging. When that engineering data *is* available, then we can see how suitable it might be for rigging.

I think it is borderline irresponsible to sell a product that was not designed to do a job without knowing how well it will work.

The fact is that rope and cable manufactures have engineered textile cables for standing rigging applications like guy wires for radio towers. Every one of those products I know of has a parallel core inside a weather-proof cover. That should tell you something.

Until you have numbers so people can engineer a rigging system properly, you should not be defending the product. Just wait until the first rig comes down and kills someone ... the answer from the rope maker will be, "We are not responsible, we did not make that product for that application."

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...

 

[RHough]

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...

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?

 

[jfranta]

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.

 

[RHough]

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.

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:

3.14.6 Lifeline Minimum Diameters, Required Materials,
Specifications
a) Lifelines shall be stranded stainless steel wire of
minimum diameter in table 8 below. Lifelines
shall be uncoated and used without close-fitting
sleeving.
**
Notwithstanding 3.14.6 (a), temporary sleeving may
be fitted provided it is regularly removed for inspection
**
b) Grade 316 stainless wire is
recommended.
**
c) A taut lanyard of synthetic rope may be used to
secure lifelines provided the gap it closes does
not exceed 100 mm (4 in). This lanyard shall be
replaced annually at a minimum.
**
d) All wire, fittings, anchorage points, fixtures and
lanyards shall comprise a lifeline enclosure
system which has at all points at least the
breaking strength of the required lifeline wire.

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:

Ultra high molecular weight polyethylene (UHMWPE), also known as high-modulus polyethylene (HMPE) or high-performance polyethylene (HPPE), is a subset of the thermoplastic polyethylene. It has extremely long chains, with molecular weight numbering in the millions, usually between 2 and 6 million. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made. It is highly resistant to corrosive chemicals, with exception of oxidizing acids. It has extremely low moisture absorption, has a very low coefficient of friction, is self-lubricating, and is highly resistant to abrasion (15 times more resistant to abrasion than carbon steel). Its coefficient of friction is significantly lower than that of nylon and acetal, and is comparable to that of Teflon, but UHMWPE has better abrasion resistance than Teflon. It is odorless, tasteless, and nontoxic.

Structure and properties

Structure of UHMWPE, with n greater than 100,000
UHMWPE is a type of polyolefin, and, despite relatively weak Van der Waals bonds between its molecules, derives ample strength from the length of each individual molecule. It is made up of extremely long chains of polyethylene, which all align in the same direction. Each chain is bonded to the others with so many Van der Waals bonds that the whole can support great tensile loads.

Under tensile load, UHMWPE will deform continually as long as the stress is present - an effect called creep.

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.

 

[Gashmore]

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

 

[RHough]

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

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!

 

[RHough]

Composite Lifelines and the Racing Rules of Sailing

FOR IMMEDIATE RELEASE

CONTACT:
Jake Fish
US SAILING Communications Manager
jakefish@ussailing.org
(401) 683-0800


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.

The Racing Rules of Sailing for 2009-2012 (RRS) rule 49.2 states that “on boats equipped with upper and lower lifelines of wire, a competitor sitting on the deck facing outboard with his waist inside the lower lifeline may have the upper part of his body outside the upper lifeline.” In an answer to a recent question posted on an ISAF question and answer page, ISAF clarified that Dyneema® is not wire and boats wishing to use the provisions of rule 49.2 will need to continue using wire for upper and lower lifelines. However, RRS 86 states that RRS 49.2 may be changed by the sailing instructions or class rules to allow the use of other materials. The full text of ISAF’s question and answer forum concerning this issue can be found at http://www.sailing.org/31312.php.

For more information on how to use Dyneema®, please read this article prepared by US SAILING Safety-at-Sea page committee members, Glenn T. McCarthy and Evans Starzinger at http://offshore.ussailing.org/SAS.htm or contact the US SAILING Offshore department at offshore@ussailing.org.

I've attached the article.

Here is what they say about splices:

The Bury is perhaps the simplest of all slices in all types of line. After making it once with instructions, most people can make it again without instructions. This splice must absolutely be lock stitched or it may slip under low load. With lock stitching it is absolutely secure. The locked Brummel is more complex and many people will require instructions each time they make it. In return for this complexity, the locked Brummel is more secure (without lock stitching) against low load slipping. However, if the buried tail is too short on a locked Brummel, the whole load can come off the ‘knot like’ locking portion and it will break at much lower than expected load. Recent testing indicates the buried tail must be 72 times the diameter of the line, which is longer than previously recommended and typically used in practice.

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

 

[RHough]

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

 

[gonzo]

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

 

[RHough]

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

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

 

[Paul B]

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.
R

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.

 

[RHough]

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.

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

 

[Paul B]

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.

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.

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.

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.

 

[RHough]

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.

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 ...

 

[Paul B]

Selling points for me are that Mom and Pop can see chafe if it is a problem

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.