Synthetic Standing Rigging With Deadeyes

[nickn]

I know that some of this has been discussed in the past, but .....
I am thinking of using spectra, dyneema or some other such plastic for "standing" rigging with perhaps deadeyes.

Keeping in mind that the boat is aluminium so I would prefer to use as little "foreign" metal as possible. I am cash poor but time rich and can fabricate deadeyes in aluminium or epoxy/polyester or even polyurethane (not really interested in lignum vitae). I am not interested in reduced weight aloft or performance enhancement. I am also 3 hours one way from the nearest rigging specialist (I wouldn't want to swage my own stainless).

I'm interested in any thoughts or experiences.

[tamicatana]

I have commercially made (Précourt) Dynex Dux (treated Dyneema) shrouds on my F-27 trimaran, have had them about 8 years now. Very good stuff.

The caveat for "terminators" (deadeyes) as I believe they're called is that you must be careful about the turning radius of the line, as a too-sharp radius will cause failure.

Dux is what you want for shrouds, though. Do a search around, it's been discussed at many fora

[Stumble]

Nick,

Colligio Marine are pretty much the experts at doing this, and do great work.

You cannot use standard dyneema, or spectra. You must use Dynex Duc. It is more expensive than dyneema, but significantly stronger, and stiffer. With less creep.

You may want to call John at Colligion and ask for some advice.

While the Dynex rigging has help up great, and does have advantages over stainless wire in most applications, it is not necessarily cheaper. The line itself generally runs about 1/2 the cost of wire, and the fittings from colligio will typically run about the same price. So your all up cost will be about the same as wire.

Of course if you machine the fittings yourself, that may save you some money, but there are a few things to keep in mind

1) the bending radius must be respected with Dynex. It will significant decrease the strength if it is bent too sharply

2) and burs or sharp edges can cut the line over time, so make sure to give them a very good polish.

[Target9000]

One question I've had...

Can you use hank on sails on Dux? Do they eventually chafe the stay?

[Stumble]

John is the expert, but I have heard of people using his soft shackles instead of hanks, and haven't heard any issues with chaff... Dynex (and dyneema for that matter) are insainly abrasion resistant.

[nickn]

I'd be interested in the reasons why spectra or dyneema couldn't be used. Is it fatigue, UV, too much stretch (ie the mast will collapse under load) or does it fall apart. I think Colligio Marine might be the antipodal point to Perth, Western Australis 8-)

[Doodles]

Originally Posted by nickn

I'd be interested in the reasons why spectra or dyneema couldn't be used. Is it fatigue, UV, too much stretch (ie the mast will collapse under load) or does it fall apart. I think Colligio Marine might be the antipodal point to Perth, Western Australis 8-)

Mostly its the stretching, but the pre-stretching done to get the Dux also makes in stronger by quite a bit.

http://www.colligomarine.com/docs/misc/DynexDuxFAQ.pdf

I replaced my wire lifelines with Dynex Dux and love it. It's easy to work with and I used my old steel turnbuckles instead of the expensive "terminators". You just need to watch any bend radiuses and not make them too sharp.

[Stumble]

Nick,

Fiber rigging is not sized to the same breaking strength as stainless wire, it is sized to control creep. The static loads on standing rigging are high enough to induce creep even if they are nowhere near high enough to reach breaking loads of the line.

Dynex Duc is dyneema. But that take standard SK-75, and heat anneal it to make the Duc. This changes the physical characteristics quite a bit.

First it reduces the diameter, so you get a stronger piece for the same size.

Second it reduces the creep of the line. Creep if you aren't familure is the elongation of a part when subject to a static load over a long period of time. For standing rigging, the creep must be controlled, otherwise you will constantly be having to redo the splices as you run out of tensioning room in the stay.

Dynex is typically sized to give you .1 inches a year of creep, to get the same creep characteristics out of standard SK-75 you would have to go up at least one size, likely two, bringing the relative cost closer to just having used the Duc in the first place.

Fiber rigging is great, but it is different than wire, and the design needs to reflect the difference.

[nickn]

The creep would not be an issue for me if I use deadeyes/lashings as they have plenty spare length. My worry would be if the creep varied say by temperature (can you have negative creep?). If the Dynex can be hand spliced as easily as dyneema/spectra then for me it would come down to price and availability with a slight leaning towards the Dynex. Keeping in mind that Western Australia is a bit of a frontier town and sometimes the unusual is really expensive. Also 90% of my enjoyment of sailing is designing/building so buying further up the food chain is not as appealing as doing it myself.

[roverhi]

The stuff is very light. Shouldn't cost much to ship it in from places very very far away. Use the internet to find the best price. Haven't spliced the Dynex Dux but understand it is the same Brummel splice as used on the Dyneema type line.

[Stumble]

Originally Posted by nickn

The creep would not be an issue for me if I use deadeyes/lashings as they have plenty spare length. My worry would be if the creep varied say by temperature (can you have negative creep?). If the Dynex can be hand spliced as easily as dyneema/spectra then for me it would come down to price and availability with a slight leaning towards the Dynex. Keeping in mind that Western Australia is a bit of a frontier town and sometimes the unusual is really expensive. Also 90% of my enjoyment of sailing is designing/building so buying further up the food chain is not as appealing as doing it myself.

Your rig, your risk.

The engineers that work with it say dyneema won't work well, and I have no reason to doubt them. But you probably could get away with it, just look at the creep tables for both types of line, and work out what your rig tension is, then size appropriately.

And no you can not have negative creep. You can have materials compress over time, but that isn't really at issue.

You can however have whats called thermal expansion. On a cold day your rig can shrink, and on a hot day it grown. This is part of why regularly retuning a rig is a necessity. Since the rig tension doesn't stay static over a range of thermal variance.

You can get the thermal expansion numbers for both dyneema and Dynex, from the manufacturers I would guess, but turning that into rigging specifications is beyond my capability.

[Stumble]

Originally Posted by roverhi

The stuff is very light. Shouldn't cost much to ship it in from places very very far away. Use the internet to find the best price. Haven't spliced the Dynex Dux but understand it is the same Brummel splice as used on the Dyneema type line.

Yup, same splice as dyneema, it is just much stiffer. So it can take a little more work to get to come out right.

[nickn]

Got a quote, $800 for 100 metres ... compares well with the price of the other stuff... so it's Dynex Dux for me.