Ratlines and Dynex?

[Bosco]

Just curious has anyone done ratlines on to Dynex Dux shrouds? if so how?

[Stumble]

I haven't seen it done, and with modern self ascenders I question the justification for them. They add a lot of windage, are useless when heeled (mostly), and put weird stresses on a critical piece of equipment.

[Ian McColgin]

Ratlines undeniably add windage. Having gone up both weather (very easy) and leeward (pretty easy) ratlines on a small (20 ton) schooner in a Strong Gale (F 9, wind about 50 kt) and having fooled about with various ascenders and halyard hoists in considerable gentler conditions, I am sold on the ratlines for any solo work and even assisted for most rough weather work.

As for the question about Dynex, however, I've no clue except that a boat employing Dynex is unlikely to be of a rigging type where ratlines make much sense anyway.

G'luck

[Stumble]

Hmmm Ian you have a point. My experience on ratlines is restricted to modern sloops where the stays don't really have enough distance between them to run them properly. The only time I had to use them I had to take of my shoes because the stays were so close together.

I still can't think of a good way to atach them to dynex stays however. My first thought was to stitch them in, but I think this would induce a weakness in the line, same problem for a clamp or wrap around the stay.

[Joe Henderson]

Dear Stumble,

I have had success with applying a short (150 mm) bit of serving at each ratline position.

Depending on the stay size, first wrap with athletic strapping tape ( white, non stretchy, 50 mm wide, vastly expensive from a drug store, better from a medical wholesaler by the box ) then serve tightly with black 3 mm V.B. cord.

Then rattle her up!.

If you have sized the dynex correctly ( see web sites and threads ad nauseum ) I dont think that any perceived weakness will amount to much, certainly no more than a clumsily excecuted eyesplice

If the stay is correctly tuned you wont be able to push a needle through anyway.

I am just in the middle of replacing, with Dynex Dux, the stays and shrouds on a 196 ton 110 foot three masted schooner. ( Weight saving about 2 1/2 tons )

I will let you know how it goes with the ratlines.

Regards,

Joe Henderson.

[Brion Toss]

Hey Joe,
Tell us more about that schooner! Oh, and I'm right there with you on bits of service. Or full-length service, for that matter. That way you get ratlines wherever you want, and essentially immortal rigging.
Fair leads,
Brion Toss

[Bosco]

I'm curious about service for dynex... any hints?

For what it's worth I'm seeing a lot of non performance boats (Westsails, Bristol Channel Cutters, etc) adopting dynex in the cruising fleet (I'm currently in the Caribbean) and one of the big draws is not so much increased performance or high tech but it's DIY marlinspike friendly that is the big draw...

[jfranta]

Originally Posted by Bosco

Just curious has anyone done ratlines on to Dynex Dux shrouds? if so how?

A couple of our customers have attached the ratline fitting (not sure of the term for this) to our line terminators that were strategically placed on the end of the shroud at a specific height above the deck. This make an easy bolting or seizing platform. Remember Dyneema hates compression, hence the large bending radii needed. Compression impact on the line strength is certainly relative to the loading of the shroud and the amount of compression induced. I certainly wouldn't clamp anything to it and if you are seizing it make sure to spread the load out well.

John Franta, Colligo Marine

[Joe Henderson]

Dear John,

What do you mean "Dyneema hates compression"

Is it as bad as Kevlar?

Have we all been wrong about the toughness of this material?

The ability of this fibre to accept tight radiuses and fairly sharp deflections, while being hammered to death, is what has enabled us to utilize it in the many and varied ways that have come to be accepted in the canon of rigging. Soft shackles spring to mind for instance.

I have never bothered in the slightest about bend radii.

How do you reconcile 'Dyneema hates compression" with the widely accepted use of larkshead/cow hitch attachments of snap shackles etc. and the use of the material in spinnaker braces with nothing more than a bit of leather around the eye that takes the clip, not to mention the nip in the pole beak or the working of the brace through the dead eye on the sheer.

I understand that the loading of standing rigging is a somewhat different scenario, but I have found that bend radius, within reason, is more a function of choosing the correct thimble to fit in the turnbuckle and tang rather than any perceived weakness or vulnerability in the material.

Even years ago, when I was making shrouds out of Kevlar 68, I found that as long as the eyes were competently and securely formed round a proper thimble the bend raduis had no effect on the strength and durability of the stay, even after several seasons on a trailer sailer catamaran.

If the fibre is sized for standing rigging according to generally accepted methods for mitigating stretch, then the breaking load is so high compared to the working load that any reduction due to being turned around a thimble is, to my way of thinking, largely irrelevant.

The fact that there is double the material ( albeit loaded in slightly divergent way around the thimble) also tends to instill confidence.

Do we need to modify our thinking re lanyards around pins for shroud attachment, for instance?

Regards,

Joe Henderson, Henderson Rigging.

[Joe Henderson]

Dear John Franta,

You may have missed my question in June regarding " Remember Dyneema hates compression"

We have now completed several standing rigging jobs using Dynex around thimbles( Both re-rig and new build, not to mention the thousands of running gear terminations we have done in Dyneema/Spectra ) and if we are missing something I would dearly like to know so I can contact our clients about any potential problems.

Regards,

Joe Henderson.