Dyneema broke at cover taper

[sailingharry]

Originally Posted by thinwater

Unless I am incorrect, it did not break at the taper, it broke at the whipping, where the cover goes into the core. The title is misleading.



You are right about taper and all that, but that is not what broke.

Yes, it broke where the cover dives into the core. The actual taper wasn't the issue.

[catsketcher]

My dyneema halyards are 10mm for a 38 footer, I would not think that 6 or 5mm is typical for a 43 footer.

I think one has to be careful about speccing a halyard based on a test lab strength test. We really want halyards to be able to be winched, turned around sheaves, knotted, spliced, have loads cycled as we go sailing and stand up to the sun hundreds of times. The effect of these other loads on a rope that is just specced on a single pull test lab result is that it will likely fail at a much lower load than thought.

I think it is a little similar to carbon laminates after being used to glass ones. I worry about thin carbon laminates after building a carbon foam boat. The specs are great for global loads and it is very stiff but you cannot think like someone with a thicker glass laminate when dealing with thin carbon laminates - they are brittle and prone to damage. So much so that they can fail in other modes you never thought of. And when they fail they just explode - no warning like wood or E glass, different failure modes from a more highly stressed part.

I like these guys when it comes to wondering how splicing and end fittings affect rope strength. Have a dive into their channel and see how rope degrade with use and terminations. They have a great setup.

https://www.youtube.com/watch?v=J2vBj5rWdXU&t=711s

cheers

Phil

[sailingharry]

Originally Posted by catsketcher

My dyneema halyards are 10mm for a 38 footer, I would not think that 6 or 5mm is typical for a 43 footer.

I think one has to be careful about speccing a halyard based on a test lab strength test. We really want halyards to be able to be winched, turned around sheaves, knotted, spliced, have loads cycled as we go sailing and stand up to the sun hundreds of times. The effect of these other loads on a rope that is just specced on a single pull test lab result is that it will likely fail at a much lower load than thought.

Phil

It is certainly not "wrong" to use 10mm dyneema on a 38 footer, but it is conservative. Samson recommends 6mm to 45', and 8mm to 50' (actually, "at least 50" because they don't provide recommendations above 50'). So, 10mm is probably appropriate for halyards on a 60'. 10mm has a listed strength of 17,000lb -- which like all lines has to be de-rated for splices, knots, chafe, UV, factor of safety, and "I don't trust it."

https://www.samsonrope.com/docs/defa..._guide_web.pdf


These are racer recommendations. They don't provide any dyneema recommendations for cruisers, presumably because of the incorrect perception that dyneema is "too expensive" for cruisers -- for a give strength (ie, a given application), dyneema stretches less, takes less room in the line bags -- and COSTS LESS!



Of course, they also recommend 1/2" nylon dock lines to 60', which few sailors do. I'm already an anomaly with 1/2" 8-plait as dock lines on my 43' boat (and I do love those lines!).

[Benz]

Originally Posted by sailingharry

I went overboard on the taper (my time is free and I do it in front of the TV when the admiral picks boring shows). I comb all strands, then split in 1/3, and bury each 1/3. The pull them fully out at the exit point, taper a long taper, and pull back in. The videos I see show to just bury in one tapered chunk. Sure will be easier!


I am puzzled by the need to taper. If taper is good (essential), as we all hear, I understand that. But, it would seem to me that the bury is a "zero length taper." The underlying dyneema is traveling along with nothing in it -- and then in 1/2 diameter, it has the full width of the cover buried inside it -- and worse, it pulls and pushes the strands aside to fit inside! How is that less stressful on the strands than an abrupt termination of the bury at the tail? No, I'm not recommending or wanting to not bury -- I'm just concerned about how sending the cover into the core isn't fatal.


My new line, from Miami Cordage, is in the mail. They "promise" that it is a full 6mm, and the fiber comes from a US fiber mill. They only make blue (which is what I wanted anyway), but I wish they made some other colors. 6mm of US made line at $0.63/ft sounds good to me.

When you bury a tail, you're pushing the core strands to the side to open up a hole--it's a small deflection mostly on one side. But when you have an abrupt stop to the bury with no taper, there's a significant shelf that all the strands have to bend over at the same spot.
You're right that the place where the bury dives in has some stress: one highly-strung boat had the core cutting the tail of the bury right where it entered, it was being pulled so hard! But the stress riser at the far end is still worse.

BTW, the silver or gray coating seems to be the most colorfast. Blue, red, and green bleed all over the place.

[catsketcher]

Olds rope fails at low specs

https://www.youtube.com/watch?v=xwajKp7x1X4

Tapering is important

https://www.youtube.com/watch?v=xwajKp7x1X4

So I would be thinking that larger diameter, cheaper halyards are safer and operate better for winches, clutches and can cope with UV and abrasion better. Spectra would be a good fit.

To save money when buying halyards my brother and I went halvies in two rolls. It was Spectra and has a breaking strain of 4000kg. Cost $440 AUD back 3 years ago for a 100m roll. But I still have quite a few halyards the same colour.

cheers

Phil

[Benz]

Originally Posted by catsketcher

Olds rope fails at low specs

Tapering is important

So I would be thinking that larger diameter, cheaper halyards are safer and operate better for winches, clutches and can cope with UV and abrasion better. Spectra would be a good fit.

To save money when buying halyards my brother and I went halvies in two rolls. It was Spectra and has a breaking strain of 4000kg. Cost $440 AUD back 3 years ago for a 100m roll. But I still have quite a few halyards the same colour.

cheers

Phil

Well, it's rather vague to say "old rope," given all the variety in materials and construction. The video tests old arborist rope, something that has no place on a boat to begin with (it's specialized for a specific use), and gets abused almost beyond imagination.
Polypropilene in the sun will lose more % of its strength than polyester, and Vectran even more than Polypro.
Given the high-sun usage, I think the OP should get a length of Dyneema that's covered all the way.

[sailingharry]

Originally Posted by Benz

Given the high-sun usage, I think the OP should get a length of Dyneema that's covered all the way.

Dyneema (and Spectra --same stuff) is very commonly used without cover. One huge "benefit" of covered Dyneema is the ability to remove a large percentage of the cover where not winched -- by adding cover as I do, I save considerable material cost (and of course replace that with my "free" labor!) -- but the normal approach with covered line is to have the majority uncovered.


In addition to running rigging, like halyards and sheets and such (my 80' sheets for my asym have about 15' of cover, a real joy to use!), a lot of Dyneema is purchased and used 100% without cover. Standing rigging, lifelines, etc are 24/7/365 in the sun with no cover. Standing rigging is normally slightly upsized for stretch considerations, but lifelines are normally spec'd the same diameter as the stainless it replaces (because larger won't fit through the stanchions) -- but I don't think I've ever seen "UV Degradation Allowance" explicitly accounted for (it's presumably rolled into the general factor of safety).


As compared to other, higher performing materials, like Kevlar, UV tolerance is a touted benefit of UHMWPE (Dyneema/Spectra), and uncovered use is common.


An unfortunate impact of going to a fully covered dyneema product is that the benefits of dyneema are greatly reduced. The total cost goes from cheaper than dacron to more expensive, the pile of line is as big as the dacron pile, when wet it is the same soggy mess, the weight aloft is nearly the same as dacron -- you only retain the outstanding strength/stretch benefits.

[s/v Jedi]

When diameters of rope are mentioned, like 10mm Dyneema, it is crucial to know if this is a bare single braid or with a braided cover etc.

Aboard Jedi, we use 6mm Amsteel Blue halyards. Where these meet the rope clutch and winch, we add a polyester cover which makes it around 9mm.

Yes, the Amsteel Blue coating stains. I recommend to simply ignore it. It better than the stains from wire…

About splicing the cover: I started with combing the strands and splicing in bundles too but once I tried the “quick” method and found it was reliable, I kept at that. It’s important to tension the rope, getting rid of constructional elongation, then fixing the spot where the core comes out the cover with a pin, before splicing the cover in. I keep massaging and rolling and tucking it until it lays neat, then I use scissors to cut the cover at a sharp angle over 4” or so before pulling it back in. Then tension it again. Lately I use two small stitched whippings to lock the splice.

With these failures at hand, I would use the Samson Warpspeed, saving any stripped cover and using that cover with Amsteel Blue again so as not to waste any material and save some $$$

I would not oversize, it’s simply too expensive and much easier to replace when needed. My halyards are still fine after years and years of hard use.

Some other measurements: my main mast is 60’ from deck and the mizzen is 50’ from deck. I use 3/8” Amsteel Blue for running backstays and 5/16” Amsteel Blue for the 2:1 running tails, which are spliced to 12mm xls3 doublebraid for the part that is only use to store the stays when not in use. I remove 10’ of core of the xls3 so that the Amsteel replaces the core for the part that is on the winch.
The last backstays lasted 19 years without sign of failure so I guess this shows the quality of Amsteel Blue and that in the end it is the more affordable solution.

For lock stitching normal splices I use 2mm nylon and I use a blunt needle that I got from Amazon as a paracord splicing needle. I go in between the strands and don’t make it tight… exactly conform Samson instructions. I think I posted a picture of that lock stitch up thread.

[sailingharry]

Originally Posted by s/v Jedi

Aboard Jedi, we use 6mm Amsteel Blue halyards. Where these meet the rope clutch and winch, we add a polyester cover which makes it around 9mm.


It’s important to tension the rope, getting rid of constructional elongation, then fixing the spot where the core comes out the cover with a pin, before splicing the cover in.

You just stated you use 6mm for your halyard. It sort of reminds my foggy memory, but I'm pretty sure I knew that, and knew you were happy, and used that knowledge as validation when I settled on 6mm for my halyards. Of course, yours is both a "real" 6mm, and the Amsteel Blue adds another ~10% to the strength. But the takeaway remains -- 6mm Dyneema is the right size for my 43' boat (mast about 58' off the deck).


The constructional stretch is real! My first project was jib halyards. These are roller furling, meaning they get hoisted once a year, and the 60' of tail languishes around on deck all year long, untouched. With Dyneema, I only covered the 10' from where it comes out of the mast, through the clutch, and into the storage locker. The remaining 120' is bare Dyneema. It's a little challenging to hoist (takes 8 turns on the winch, and the tailer barely holds it), but storing a handful of Dyneema is worlds better than storing 60' of 1/2 VPC -- and double that for two sails! But, I put my beautiful halyards in, hoisted the sail, cranked a good luff tension on it -- and found my cover was located 5 feet from where it was supposed to be! Back to the couch in front of another TV show for some rework....LOL. Just to reiterate your point (and my experience) -- YOU MUST PRE-TENSION BEFORE MAKING CRITICAL MEASUREMENTS! And I now make that "pre-tension" with as much force as I can apply, and let it sit for a while.

[s/v Jedi]

Originally Posted by sailingharry

You just stated you use 6mm for your halyard. It sort of reminds my foggy memory, but I'm pretty sure I knew that, and knew you were happy, and used that knowledge as validation when I settled on 6mm for my halyards. Of course, yours is both a "real" 6mm, and the Amsteel Blue adds another ~10% to the strength. But the takeaway remains -- 6mm Dyneema is the right size for my 43' boat (mast about 58' off the deck).


The constructional stretch is real! My first project was jib halyards. These are roller furling, meaning they get hoisted once a year, and the 60' of tail languishes around on deck all year long, untouched. With Dyneema, I only covered the 10' from where it comes out of the mast, through the clutch, and into the storage locker. The remaining 120' is bare Dyneema. It's a little challenging to hoist (takes 8 turns on the winch, and the tailer barely holds it), but storing a handful of Dyneema is worlds better than storing 60' of 1/2 VPC -- and double that for two sails! But, I put my beautiful halyards in, hoisted the sail, cranked a good luff tension on it -- and found my cover was located 5 feet from where it was supposed to be! Back to the couch in front of another TV show for some rework....LOL. Just to reiterate your point (and my experience) -- YOU MUST PRE-TENSION BEFORE MAKING CRITICAL MEASUREMENTS! And I now make that "pre-tension" with as much force as I can apply, and let it sit for a while.

For a jib halyard, you don’t need Dyneema for the part that is coiled up when the jib is on the furler. Simply use 10mm xls3 double braid polyester for that and splice the two together. Just like the old halyards that used stainless 7x19 wire.
From the xls3, remove 10’ of core and then splice the 6mm Amsteel Blue to the xls3 core, then milk the cover over the splice and the Amsteel so that the part of the Amsteel that is in the clutch and on the winch has the cover. Then open the cover 12” from the end and pull the whole length of Amsteel trough, then splice the 12” cover back into the Amsteel, tapering it etc.

[sailingharry]

Originally Posted by s/v Jedi

For a jib halyard, you don’t need Dyneema for the part that is coiled up when the jib is on the furler. Simply use 10mm xls3 double braid polyester for that and splice the two together. Just like the old halyards that used stainless 7x19 wire.
From the xls3, remove 10’ of core and then splice the 6mm Amsteel Blue to the xls3 core, then milk the cover over the splice and the Amsteel so that the part of the Amsteel that is in the clutch and on the winch has the cover. Then open the cover 12” from the end and pull the whole length of Amsteel trough, then splice the 12” cover back into the Amsteel, tapering it etc.

Agreed, you don't "need" Dyneema. But the benefit is huge! My 60' tail, of 6mm Dyneema, is much smaller than that same tail in 10mm (about 1/2 the volume). And the Dyneema is more limp so it lays better, and it holds zero water, so any rain that gets into the storage locker doesn't make a wet moldy mess (at the base of my mast, on each side, is a locker about 2' x 2', about 5" deep, with a lid that folds down -- with the old double braid the lid wouldn't close, but with Dyneema it has ample left over space).


On the main halyard, most of those benefits fade away. With 10' covered for winch/clutch at 4 locations (full hoist and 3 reefs), almost 40' of the 60' tail is covered. The only benefit remaining is the strength/stretch properties. Although in my crappy "6mm" and my poor whipping at the top, I didn't get to enjoy the "strength" for very long....



But your approach to splicing Dyneema to double braid is interesting, and I'd like to find an application so I can give it a try!

[fivecapes]

Originally Posted by s/v Jedi

...I would use the Samson Warpspeed, saving any stripped cover and using that cover with Amsteel Blue again so as not to waste any material and save some $$$

What size/s Warpspeed would you use to strip the cover for the 6mm Amsteel Blue?
Where would you suggest using the stripped Warpspeed? (sheets spliced to Amsteel?)

[s/v Jedi]

Originally Posted by fivecapes

What size/s Warpspeed would you use to strip the cover for the 6mm Amsteel Blue?
Where would you suggest using the stripped Warpspeed? (sheets spliced to Amsteel?)

Warpspeed II 3/8” has an Amsteel Blue 1/4” core.

I use stripped lines for roller furler lines, halyards, running backstay tails. If I would be racing, I would use them for sheets of headsails, spinnakers too.

About bare Amsteel on a winch: I have no problems with 6 wraps around the drum followed by the self tailer where for covered lines 3 wraps is enough.

[Benz]

Originally Posted by sailingharry

An unfortunate impact of going to a fully covered dyneema product is that the benefits of dyneema are greatly reduced. The total cost goes from cheaper than dacron to more expensive, the pile of line is as big as the dacron pile, when wet it is the same soggy mess, the weight aloft is nearly the same as dacron -- you only retain the outstanding strength/stretch benefits.

There is still the benefit of being able to step down the size while retaining strength--that makes the rope pile smaller--and anyone who thinks a piece of dyneema-cored line weighs as much as a piece of polyester double braid hasn't carried a lot of both. There's a significant weight difference.
So, smaller diameter, and a lot less weight.
As for cost, a covered dyneema halyard will last longer than uncovered--surely longevity factors into the cost-benefit analysis. And if the cover goes, the core can be re-covered more cheaply than replacing the whole rope. I have just re-covered 20-odd spinnaker halyards for a racing fleet, giving them a new lease on life.

[twofingerpoi]

Miami Cordage is a quality vendor.

I typically use Samson MLX3 for my halyards and other running rigging.

I would not trust cheap lines for critical lines, although I have had good results with dock and fender lines from Amarine on Amazon.