Dyneema instead of stainless for stays and shrouds

[jfranta]

Can you please contact me? Email or call. I do not know who you are from your ID on here or I would contact you. We have been very busy and growing, maybe too fast, and I do not like to see anyone waiting for anything. jfranta@colligomarine.com or 001 480 703 3675. I apoliogize for any delays.

John

Originally Posted by kryg

Frankly I have a different negative experience with John Franta, Colligo.

After receiving his email advert, I contacted John and agreed to sent sail plans and detailed photos of my rigging and information for Skoiern to change the rigging to Synthetic for a quote. After he receive my information he never bothered to reply to a number of follow up emails. I have no idea what he has done with my boat drawings. rigging photos and detail boat information.

Yet I still receive his Colligo emails on his products. Typical case of that the right hand is doing the left hand does not see.

I find that a person or company who does not reply or is too lazy to recognize the effort in supplying best information for a quote can't be relied on.

[jzk]

Is there any concern that using Dyneema for shrouds might actually cause a failure, especially on a multihull?

With a monohull, the boat rolls and heels, so impact forces on the rig are never really that great. But with a multihull, there is less heeling and giving. So when there is an impact force, it has to be absorbed somewhere. If dyneema has less stretch and give than stainless, where are those impact forces absorbed?

One reason I ask is because I saw the catastrophic hull failure experienced by SV Zingaro after going to dyneema.

[slug]

Originally Posted by jzk

Is there any concern that using Dyneema for shrouds might actually cause a failure, especially on a multihull?

With a monohull, the boat rolls and heels, so impact forces on the rig are never really that great. But with a multihull, there is less heeling and giving. So when there is an impact force, it has to be absorbed somewhere. If dyneema has less stretch and give than stainless, where are those impact forces absorbed?

One reason I ask is because I saw the catastrophic hull failure experienced by SV Zingaro after going to dyneema.

Dyneema can loose up to ten percent of its strength per year from environmental damage . Primarily UV
Additionally dyneema is damaged by chafe

Be aware if you decide to use fabric rigging

[Boatguy30]

I personally think the applications are somewhat limited and have only sold it to customers that specifically want it. It for sure had nothing to do with an old boats structural failure!

[jzk]

Originally Posted by Boatguy30

I personally think the applications are somewhat limited and have only sold it to customers that specifically want it. It for sure had nothing to do with an old boats structural failure!

"For sure" is an interesting conclusion. I am just wondering if the Dyneema can cause higher shock loads to be transmitted to a vessel.

[Boatguy30]

Most cats use dyform which is lesser stretch than dyneema. A weak cat is a weak cat. Can't close the head doors on a Leopard 40 if the rig is 2 turns to tight!

[jzk]

Originally Posted by Boatguy30

Most cats use dyform which is lesser stretch than dyneema. A weak cat is a weak cat. Can't close the head doors on a Leopard 40 if the rig is 2 turns to tight!

That is not the point at all. The point is whether an old, weak cat is better off with Dyneema for the rig or worse off. It may be that it is worse off.

[Boatguy30]

It is? Unfit is unfit

[fxykty]

Originally Posted by jzk

"For sure" is an interesting conclusion. I am just wondering if the Dyneema can cause higher shock loads to be transmitted to a vessel.

How would Dyneema rigging cause higher shock loads than wire? If both are strong enough to not break and Dyneema is sized so it’s stretch is similar to wire then how would one material or the other cause higher shock loads?

Regarding the fuse idea, ASFAIK no rig is designed to fail above a certain load where that load is several times higher than the highest expected load on the rig (for a cat, the peak of the righting curve is generally just as the windward hull lifts clear of the water). A fuse would be very dangerous for the people on board - a rig collapsing is a chaotic event that cannot be planned.

[Sailmonkey]

Originally Posted by jzk

"For sure" is an interesting conclusion. I am just wondering if the Dyneema can cause higher shock loads to be transmitted to a vessel.

If you’re experiencing shock loads from your rig, it’s that the rigging is too loose, nothing to do with the rigging material.

[fxykty]

Originally Posted by SV Windrush II

Im on the Colligo web site. Great setup they have to order rigging. Everything is very pricy of course.



I notice they say the aluminum is "Aircraft Grade" which is almost meaningless since there are many different grades of aluminum that the aerospace industry uses.

Myself coming from the aerospace industry as a materials and composites expert its almost a comical expression to me. Im assuming they mean some kind of alloy like 6082 for marine use.



Im surprized they do not use titanium for the prices they charge. Also i know of a chopped carbon fiber PE composite mix that would be stronger than any aluminum alloy and not have the erosion problems of aluminum. Andonized finish wears off after awhile.

I was sent the construction drawing for Cheeky Tangs 15-17 by John Franta of Colligo. The material is specified as “Aluminum 6061-T6”. Finish is specified as “Polished, Hardcoat Anodized per MIL-A-8625 Type lll, Black”. Does that qualify as aircraft grade?

I haven’t had any of their gear for very long so don’t know about longer term polishing of the finish. But ASFAIK low friction rings from most suppliers are anodised aluminium and I’m not seeing any wear on several rings that are three years old.

[billknny]

There is a lot of misinformation being thrown around here. Comments like "dyform stretches less than dyneema" shows a misunderstanding about how dyneema rigging is actually (or should be!) sized for a boat.

First, you do NOT replace a 3/8" stainless wire with a 3/8" dyneema. (It would be too weak)

Second, you do NOT replace a 3/8" stainless wire with a dyneema line that has the same breaking strength. (It would be too stretchy)

You actually size the dyneema so under rigging loads it has the SAME STRETCH as the wire rigging it is replacing.

On the down side, this means that the dyneema is quite a bit larger in diameter than the wire it replaces, so more windage. But it is still a LOT lighter, and has a much higher ultimate breaking strength than the old wire. 3 or 5 times stronger. It could lose 10% of its strength every year for 10 years and STILL be stronger than the original wire!

So... if a boat's dyneema rig stretches more than the wire it replaced it was sized incorrectly. Period. Not the dyneema's fault, but the rigger who installed it.

[jtsailjt]

Originally Posted by Sailmonkey

If you’re experiencing shock loads from your rig, it’s that the rigging is too loose, nothing to do with the rigging material.

I think the concern is that shrouds with virtually no ability to stretch at all would transfer 100% of sudden or impact loads to the hull structure and that would be more likely to lead to failure than if the shrouds had some elasticity. But I don’t think the assumption that Dyneema shrouds have less stretch than stainless is valid unless they are very much larger, and since stainless shrouds have so little ability to stretch, even if very large Dyneema was used, the loads on the hull won’t change by any detectable amount, certainly not enough to lead to structural failure of the hull.

You’re right that too loose rigging is much more likely to cause shock loading than is too little stretchiness in the standing rigging but that is a function operator error when the rig is tuned rather than the material being used.