49 replies to this topic

[RobG]

I'd like to understand the pros and cons of various rigging materials for use in small, high performance boats.

Stainless steel wire is pretty ubiquitous, however materials like Dyneema and Spectra are potentially easier to work with and lighter. More exotic materials like PBO and C6 are extremely light but also hugely more expensive and probably less robust. Ideally someone will have a link to a comparison of strength, weight, robustness, stretch and so on but that isn't likely so opinion based on experience is next best.

My boat is a Moth but I'm sure experience with various materials in any small skiff will be of assistance.

And yes, I've asked on a Moth forum but those who participate in forums all seem to hang out here these days.


--
Rob

[Greenflash]

Hey Rob

I am actually interested in this also. I was considering changing the wire rigging on a 6m sportboat to dyneema but someone said it stretches too much.

But I know that you can take the creep out of dyneema by pre-stretching it... think Chainblock and two trees....

PBO has to be properly woven to be effective , no? And it needs to be covered because UV kills it.

I have seen a 25 ft Trimaran rigged out (shrouds, FS, BS) Completely with Dynex Dux.. which is Dyneema that is treated with a coating and pre-stretched.

I really don't see why you couldn't change your shrouds and Forestay to Dyneema if properly stretched, on your moth.

On a keelboat I have heard PBO is the best for Shrouds because it has the least creep and then use Dyneema for FS and BS because is handles the fatigue better.

I dont know much about Carbon, C6 etc.

Actually I dont know that much about any of this (No surprise there!) so good thread... I bet this has been discussed before tho...

Gf

[Major Tom]

If you want to be sure that your rig is going to stay up with the minimum of hastles then stay with wire. Carbon is extremely fragile as it will snap if it is folded or kinked, how often do your shrouds hook on something as you are raising the mast? PBO is nice as it is almost zero stretch, but does not like anything rubbing against it and needs protection from UV. Dyneema is the cheapest of the 'exotics' and it would be my choice if I was prepared to change them regularly. It does initially have a bit of creep when it is put under load.
My 2c...........

[auscat]

A mate changed his stays and trap wires on his 505 to some kind of fishing line.We used the rest to lash on tramps.
About 2-3mm grey waxy stuff.Did a kind of strength test by towing a mates ute down the road and slowly applying the brake till it broke.
Held for longer than any of us thought.

[Luke Piewalker]

You might be able to take the stretch out by pre stretching, but creep is a fundamental property of the material that is always present.

[Suppenkelle]

And yes, I've asked on a Moth forum but those who participate in forums all seem to hang out here these days.
--
Rob

I'm shure Doug would prefer to see us discussing this on the IMCA forum. :-)
I used Dyneema on my Velociraptor which was pretty good. It is still used now in the 3rd season. It was lightweight and easy to handle but didn't feel very stiff. Maybe this was because the boat wasn't very stiff in itself.
On my Mach2 at first I had a PBO rigging. I did not trust it and it came down eventually. Now I use wire as in the old lowriding days. no maintenance no special care needed.

If I were to change again, it would be Dyneema but not PBO.
Maybe this is due to the fact that I can make wire and Dyneema riggigs on my own but not PBO. Somehow I came to trusting my own work more than a manufacturer's. Probably nonsense.

Burkh

[aardvark_issues]

I've only got experience of the Marlow SK78. I wouldn't trust any spliced rope on a Moth due to the rigging/derigging aspect and the fact that you are pretty much back to square one with creep every time you rig the boat. I'm sure my splicing could be better but just can't see how it can maintain rig tension unless you leave the mast up...

[rastus]

I have been using Dynex for the last few years on my fd no problems

[aus2479]

looking at the c6 on a moth I reckon it looks like it might have cheese slicer affect if you hit it, although looks pretty cool. I will be sticking with wire though as cheap and easy.

[Bill E Goat]

12's are starting to change to carbon rod, cheap as and easy to work with, not so good in a hard collision

[Fishingmickey]

I've been using the 3 mm Vectran on my Contender shrouds and forestay for about 4 years now. I've replaced the original rigging (shrouds the year before and forestay last year). It looks like about 2 years of sailing before the shroud fuzz makes me change it out.
FM
I've been fairly pleased with it and I do get some stretch initially.

[BalticBandit]

I tried using Dyneema on a halyard and prestretching it myself. It never worked quite right. went back to Vectran

The biggest problem with dyneema as someone pointed out, is that it creeps. Sure you can adjust it over time but that means that repeatable settings are harder to come by. Boats like I14s can deal with this because they have set "rake" and "bend" numbers that they periodically check against.

Swift Solos use Vectran and and PBO in some of their rigging. Chafe and UV are the issue there.

Carbon rod looks cool (I've not used it) but may be too brittle for the application you want to use it for - I wonder why no-one has created a Carbon/Kevlar hybrid rod.

[jmart]

Check out http://www.colligomarine.com and go to the FAQ section and Synthetic Rigging section. At least you'll get some info about their products compared to wire and rod.

From what I gather, although Dux is a Dyneema product, due to the heating & pre-stetching, creep is reduced. They do admit you can experience some constructional creep at splices, but once the rigging is tensioned, the creep is set and after that it is essentially zero.

Smallest diameter available is 3/16" / 5mm, no smaller options for dinghy rigging. 3/16" is fine, it's just overkill.

It can get pricey by the time you add the price of the fittings.

[Luke Piewalker]

I read it slightly differently. What they are talking about is the 'settling' of the braid in a splice. Creep remains the same as it ever was until it breaks.

[jmart]

They list two types of creep/stretch: constructional and material. The constructional stretch is as you say, "settling in" of a splice, a knot, etc. The material stretch is the basic degree to which the cordage stretches when under a static load. The Dux supposedely has virtually zero material stretch and some constructional stretch where you splice it, until it settles in.

[DancingBear]

SK 78 and SK 90 Dyneema has negligible creep and is U/V stable. The improvements in the amount of creep in SK 78 and SK 90 is huge, most Melges 32s are now using SK 90 for all upwind and downwind halyards because it is lighter than Vectran and will not creep.

[RobG]

All good information.

I think I've narrowed it down to either:

• SK90 - 3mm dia (the smallest available I think), weight 460g/100m and breaking strain of 1050kg, AUD3.60/m or
• SK75 - 2mm dia, weight 180g/100m and breaking strain of 410kg, AUD1.75/m.

I'm leaning toward 2mm SK75 as it's about the same dia as PBO and half the weight - 8g per shroud. Does the breaking strain seem OK? I have no idea what the loads are on a Moth.

The attractive part of 3mm SK90 is that it is about the same weight as PBO and given it's high breaking strain, creep should be minimal. But it's a bit thick at 3mm. Price isn't really an issue given the quantities I'll be using even though SK90 is twice the cost of SK75 (either option would be about 1/5th or less than the cost of PBO or C6).


Oh, and Dyneema comes in colours - no more boring black!

--
Rob

[John D]

All good information.

I think I've narrowed it down to either:

• SK90 - 3mm dia (the smallest available I think), weight 460g/100m and breaking strain of 1050kg, AUD3.60/m or
• SK75 - 2mm dia, weight 180g/100m and breaking strain of 410kg, AUD1.75/m.

I'm leaning toward 2mm SK75 as it's about the same dia as PBO and half the weight - 8g per shroud. Does the breaking strain seem OK? I have no idea what the loads are on a Moth.

The attractive part of 3mm SK90 is that it is about the same weight as PBO and given it's high breaking strain, creep should be minimal. But it's a bit thick at 3mm. Price isn't really an issue given the quantities I'll be using even though SK90 is twice the cost of SK75 (either option would be about 1/5th or less than the cost of PBO or C6).


Oh, and Dyneema comes in colours - no more boring black!
-
Rob

Rob, can U get SK75 & 90 in 2 or 3 mm in the states?

[RobG]

Rob, can U get SK75 & 90 in 2 or 3 mm in the states?

Links I have found to online shops:

• Colligo Marine Dynex Dux has a minimum listed dia of 5mm but you may be able to get it smaller. It seems to me that Dynex Dux is pre-streched and heat treated SK75 that removes the constructional stretch and leaves only material stretch (that's the claim anyway)
• APS 3mm AS-90 Dyneema I think it's the same stuff as Dyneema SK 90
• DeckHardware (Aust) 3mm SK 90 if you want to try outside USA. They seem pretty reasonable and shipping isn't too expensive
• Performance Pro (Aust) LYROS D PRO (Dyneema SK 75) 1mm upward, but might stretch a bit more than similar diameter SK 90

Are you looking to use 3mm for rigging? On what type of boat?

I am now leaning toward 3mm SK 90 because it should have lower stretch. There is a related thread in Gear Anarchy: Dyneema replacement for stainless wire on Moth.


--
Rob

[constantijn]

please remember that rigging has to be designed on stretch with a minimal break load.

There are a shit load of factors to take into account.
I will skip the fattigue life, handling difficulties, costs and lifespan in this comparisson

there are a number of factors which account for the overall stretch of a certain piece of rigging.

construction: (less to most stetch)
solid or UD (think rod rigging, UD PBO or carbon)
spiraled construction (dyform/ wire)
braided construction (various ropes)

UD or rod has no construction stretch, braided ropes can have up to 30%!!!!!! construction stretch.
this construction stretch can be pulled out of the material by pretensioning. basically, the more air there is in the construction, the more stretch it will give.
each time you coil a piece of braided rigging, some of the construction stretch will return.

material properties:
the stecth of the raw materials are best described with the E modulus (Hooke's law). this will tell you the elongation at a certain load for a given cross section. after you release the load, it will return to original length

Carbon(T800) 300GPa
PBO 245GPa
Rod/ steel 190GPa
Dyneema/ spectra110GPa
Aramid 110GPa
Vectran 75 GPA

for the same stretch as PBO you will need more then 2 times the cross section of dyneema

Next to these properties there is creep. creep is like a piece of gum you pull, it will keep elongating untill it breaks. dont be fooled, this cannot be taken out of Dyneema/ spectra.
creep from low to high. Creep can be reduced by reducing the load (so more fibres/ cross section, but this means higher diameter)
SK 78
SK 75
SK 90 (this means that has the most creep, but the highest breakload of all dyneemas)


Then there is density or SG (light to heavy)
dyneema 1
vectran
aramid
pbo
carbo all around 1,5 (please note that the carbon will need about 30 (mass) % of resin)
steel 7.8

UV
for pbo, aramid and vectran, these fibres will loose strength (at various speeds) due to UV, so the will need some kind of cover.


Diameter (including cover if necesary)(for stetch equivalent)
carbon/ rod
pbo ud
aramid ud
dyneema rope
vectran rope

the ropes are easy to diy, the wire and rod have most different types of endfittings.


From performance point of view (low weigth, low stretch, low diameter) either Carbo or PBO is the best (carbon can be fragile, pbo loses strength
a good budget version is dyform (good availability, low stretch), wire is even cheaper
dyneemas are good for diy, but will always creep and have construction stretch. if strength is your only concern this is the best. (use the 78 or 75!)

my 2 cents,

[AUS]

We are the dist for FSE Robline in the US. We have SK90 in 2mm listed in the catalogue (ocean 7000)as well as 3mm but have not stocked any due to limited interest pre season. If any of our stockist asks for it I will see what we can do.
http://www.teufelber...ocean-7000.html

[skiffboy]

please remember that rigging has to be designed on stretch with a minimal break load.

There are a shit load of factors to take into account.
I will skip the fattigue life, handling difficulties, costs and lifespan in this comparisson

there are a number of factors which account for the overall stretch of a certain piece of rigging.

construction: (less to most stetch)
solid or UD (think rod rigging, UD PBO or carbon)
spiraled construction (dyform/ wire)
braided construction (various ropes)

UD or rod has no construction stretch, braided ropes can have up to 30%!!!!!! construction stretch.
this construction stretch can be pulled out of the material by pretensioning. basically, the more air there is in the construction, the more stretch it will give.
each time you coil a piece of braided rigging, some of the construction stretch will return.

material properties:
the stecth of the raw materials are best described with the E modulus (Hooke's law). this will tell you the elongation at a certain load for a given cross section. after you release the load, it will return to original length

Carbon(T800) 300GPa
PBO 245GPa
Rod/ steel 190GPa
Dyneema/ spectra110GPa
Aramid 110GPa
Vectran 75 GPA

for the same stretch as PBO you will need more then 2 times the cross section of dyneema

Next to these properties there is creep. creep is like a piece of gum you pull, it will keep elongating untill it breaks. dont be fooled, this cannot be taken out of Dyneema/ spectra.
creep from low to high. Creep can be reduced by reducing the load (so more fibres/ cross section, but this means higher diameter)
SK 78
SK 75
SK 90 (this means that has the most creep, but the highest breakload of all dyneemas)


Then there is density or SG (light to heavy)
dyneema 1
vectran
aramid
pbo
carbo all around 1,5 (please note that the carbon will need about 30 (mass) % of resin)
steel 7.8

UV
for pbo, aramid and vectran, these fibres will loose strength (at various speeds) due to UV, so the will need some kind of cover.


Diameter (including cover if necesary)(for stetch equivalent)
carbon/ rod
pbo ud
aramid ud
dyneema rope
vectran rope

the ropes are easy to diy, the wire and rod have most different types of endfittings.


From performance point of view (low weigth, low stretch, low diameter) either Carbo or PBO is the best (carbon can be fragile, pbo loses strength
a good budget version is dyform (good availability, low stretch), wire is even cheaper
dyneemas are good for diy, but will always creep and have construction stretch. if strength is your only concern this is the best. (use the 78 or 75!)

my 2 cents,

noice summary.

[Mel]

Rob, can U get SK75 & 90 in 2 or 3 mm in the states?

Links I have found to online shops:

• Colligo Marine Dynex Dux has a minimum listed dia of 5mm but you may be able to get it smaller. It seems to me that Dynex Dux is pre-streched and heat treated SK75 that removes the constructional stretch and leaves only material stretch (that's the claim anyway)
• APS 3mm AS-90 Dyneema I think it's the same stuff as Dyneema SK 90
• DeckHardware (Aust) 3mm SK 90 if you want to try outside USA. They seem pretty reasonable and shipping isn't too expensive
• Performance Pro (Aust) LYROS D PRO (Dyneema SK 75) 1mm upward, but might stretch a bit more than similar diameter SK 90

Are you looking to use 3mm for rigging? On what type of boat?

I am now leaning toward 3mm SK 90 because it should have lower stretch. There is a related thread in Gear Anarchy: Dyneema replacement for stainless wire on Moth.


--
Rob

Thanks for the mention... Glad we are reasonable haha! (DeckHardware Aust) If you do want to get in touch we can try and find out more information from Liros the manufacturer. As it is all new we are still finding out the facts as they do!

[john.h]

please remember that rigging has to be designed on stretch with a minimal break load.

There are a shit load of factors to take into account.
I will skip the fattigue life, handling difficulties, costs and lifespan in this comparisson

there are a number of factors which account for the overall stretch of a certain piece of rigging.

construction: (less to most stetch)
solid or UD (think rod rigging, UD PBO or carbon)
spiraled construction (dyform/ wire)
braided construction (various ropes)

UD or rod has no construction stretch, braided ropes can have up to 30%!!!!!! construction stretch.
this construction stretch can be pulled out of the material by pretensioning. basically, the more air there is in the construction, the more stretch it will give.
each time you coil a piece of braided rigging, some of the construction stretch will return.

material properties:
the stecth of the raw materials are best described with the E modulus (Hooke's law). this will tell you the elongation at a certain load for a given cross section. after you release the load, it will return to original length

Carbon(T800) 300GPa
PBO 245GPa
Rod/ steel 190GPa
Dyneema/ spectra110GPa
Aramid 110GPa
Vectran 75 GPA

for the same stretch as PBO you will need more then 2 times the cross section of dyneema

Next to these properties there is creep. creep is like a piece of gum you pull, it will keep elongating untill it breaks. dont be fooled, this cannot be taken out of Dyneema/ spectra.
creep from low to high. Creep can be reduced by reducing the load (so more fibres/ cross section, but this means higher diameter)
SK 78
SK 75
SK 90 (this means that has the most creep, but the highest breakload of all dyneemas)


Then there is density or SG (light to heavy)
dyneema 1
vectran
aramid
pbo
carbo all around 1,5 (please note that the carbon will need about 30 (mass) % of resin)
steel 7.8

UV
for pbo, aramid and vectran, these fibres will loose strength (at various speeds) due to UV, so the will need some kind of cover.


Diameter (including cover if necesary)(for stetch equivalent)
carbon/ rod
pbo ud
aramid ud
dyneema rope
vectran rope

the ropes are easy to diy, the wire and rod have most different types of endfittings.


From performance point of view (low weigth, low stretch, low diameter) either Carbo or PBO is the best (carbon can be fragile, pbo loses strength
a good budget version is dyform (good availability, low stretch), wire is even cheaper
dyneemas are good for diy, but will always creep and have construction stretch. if strength is your only concern this is the best. (use the 78 or 75!)

my 2 cents,

very good summary. Everything is a compromise.
The Carbon Rod is the ultimate solution performance wise but is expensive, fragile and a bit of a pain to deal with. Still if I was going to a moderate air venue for a target regatta I would certainly consider using it.
We sell carbon & pbo rigging. I have pretty easy access to any of these solutions and chose to use 2.5mm dyform on the Moth. Will not fail, windage is reasonable (I would not be willing to use anything above 2.5mm due to windage), cheap & easy to deal with on shore. A little heavy..... but that I think that is a reasonable price to pay for the other benefits.

[steveromagnino]

on the first production shaw 650 we ran synthetic rigging; dyneema dux I think or equivalent.

Forestay on the Shaws runs something like 300kg, side stays (verticals) around 350kg.

We massively oversized the spec to try to reduce the issue of creep; however it became on ongoing issue that you needed to adjust the rigging during the day to keep the tensions as you wanted.

You cannot run tensions anything like the breaking strain, and expect to have a minimal amount of stretch.

A major weight saving, but the only true way to really save weight is to also eliminate all the fittings at each end of each stay as well, no heavy turnbuckles or T hooks, run everthing into synthetics and lashings, which you probably do on a moth.

And then it becomes tricky to fiddle around with things and replicate settings....but very light.

If you are running lower rig loads than this, then maybe it will work, but certainly sportsboats still need a bit more development from where we are now for people to go synthetic from dyform.

[jfranta]

on the first production shaw 650 we ran synthetic rigging; dyneema dux I think or equivalent.

Forestay on the Shaws runs something like 300kg, side stays (verticals) around 350kg.

We massively oversized the spec to try to reduce the issue of creep; however it became on ongoing issue that you needed to adjust the rigging during the day to keep the tensions as you wanted.



If you are running lower rig loads than this, then maybe it will work, but certainly sportsboats still need a bit more development from where we are now for people to go synthetic from dyform.

Good thread here.

If you are experiencing creep with Dux Standing rigging then you have not sized it correctly. We design our rigs for 0.1 inches of creep per year (1 inch in 10 years). We know exactly what the creep is in dyneema and have been able to size for it successfully. It usually results in a slight increase in diameter from wire, 1x19 1/4" is stretch equivalant to 7mm Dux mm and can handle about 500 lbs of constant tension at the 0.1" per year benchmark. On campaigned sportboats we would probably use 9 mm dux that can handle about 1200 lbs of constant load (pretension) at 0.1" per year creep. So going from 6.4 mm (1/4 inch) in diameter to 9 mm for a slight increase in windage. In the 9 mm scenario you would now have a rig that stretches less so you would need less pretension than the wire had. We have successfully rigged many diamond stays which have very high relative pretension, constantly, so presents a good challenge for Dyneema derived rigging.

For Onshore boats we size the rigging for creep based on the pretension only. For Offshore boats we also factor in the dynamic loads as they spend a good deal more time at the higher loads. We just rigged an open 60 with Colligo Dux that uses a mast ram, 10,000 lbs of pretension but dynamic loads as high as 20,000 lbs predicted by the designer. This boat will spend a good amount of time at sea at higher loads so we needed to factor them in. This boat represents the biggest challenge to Colligo Dux rigging to date and we are anxious to see the results but based on previous boat's data it should be fine. Stay tuned for more info on this boat as time goes by.

It is interesting to note that no one has ever complained about windage on any of the boats we have rigged and we have now built over 500 Colligo Dux shrouds or stays. I think the overwhelming benefits from the weight savings override the slight increase in diameter. It is easy to visualize how an increase in rigging diameter adds to windage and not quite as easy to see how an increase in righting moment adds to performance.

Cost is a big factor in moving to synthetics, Colligo Dux is about 1/3rd the cost of PBO and 1/5th the costs of Carbon so I think dyneema is a good option for synthetic standing rigging as long as the limiting parameters, stretch and creep, are addressed.

Also keep in mind the durability and expected life. There are always compromises in any engineering situation but dyneema keeps coming up to the top for UV, damage from water exposure, and chafe resistance, especially when you factor in cost.

John Franta, Colligo Marine.

[john.h]

on the first production shaw 650 we ran synthetic rigging; dyneema dux I think or equivalent.

Forestay on the Shaws runs something like 300kg, side stays (verticals) around 350kg.

We massively oversized the spec to try to reduce the issue of creep; however it became on ongoing issue that you needed to adjust the rigging during the day to keep the tensions as you wanted.



If you are running lower rig loads than this, then maybe it will work, but certainly sportsboats still need a bit more development from where we are now for people to go synthetic from dyform.

Good thread here.

If you are experiencing creep with Dux Standing rigging then you have not sized it correctly. We design our rigs for 0.1 inches of creep per year (1 inch in 10 years). We know exactly what the creep is in dyneema and have been able to size for it successfully. It usually results in a slight increase in diameter from wire, 1x19 1/4" is stretch equivalant to 7mm Dux mm and can handle about 500 lbs of constant tension at the 0.1" per year benchmark. On campaigned sportboats we would probably use 9 mm dux that can handle about 1200 lbs of constant load (pretension) at 0.1" per year creep. So going from 6.4 mm (1/4 inch) in diameter to 9 mm for a slight increase in windage. In the 9 mm scenario you would now have a rig that stretches less so you would need less pretension than the wire had. We have successfully rigged many diamond stays which have very high relative pretension, constantly, so presents a good challenge for Dyneema derived rigging.

For Onshore boats we size the rigging for creep based on the pretension only. For Offshore boats we also factor in the dynamic loads as they spend a good deal more time at the higher loads. We just rigged an open 60 with Colligo Dux that uses a mast ram, 10,000 lbs of pretension but dynamic loads as high as 20,000 lbs predicted by the designer. This boat will spend a good amount of time at sea at higher loads so we needed to factor them in. This boat represents the biggest challenge to Colligo Dux rigging to date and we are anxious to see the results but based on previous boat's data it should be fine. Stay tuned for more info on this boat as time goes by.

It is interesting to note that no one has ever complained about windage on any of the boats we have rigged and we have now built over 500 Colligo Dux shrouds or stays. I think the overwhelming benefits from the weight savings override the slight increase in diameter. It is easy to visualize how an increase in rigging diameter adds to windage and not quite as easy to see how an increase in righting moment adds to performance.

Cost is a big factor in moving to synthetics, Colligo Dux is about 1/3rd the cost of PBO and 1/5th the costs of Carbon so I think dyneema is a good option for synthetic standing rigging as long as the limiting parameters, stretch and creep, are addressed.

Also keep in mind the durability and expected life. There are always compromises in any engineering situation but dyneema keeps coming up to the top for UV, damage from water exposure, and chafe resistance, especially when you factor in cost.

John Franta, Colligo Marine.

All fair enough when talking about keel boats. But on a Moth (the opening post refers to small high performance boats/moths) windage is a definate factor when going upwind at 16knots... low drag is crucial. Also as the rig is either upright or heeled to windward the grams saved between dyform & dyneema are not quite as critcal.

[furcoat]

Any clues on how to measure rig tension on PBO rigging? Can you just bung the Loos guage on it or will that damage the stay? Does loos just measure tension regardless of substrate or is it only for wire stays?

Cheers,

[jfranta]

[/quote]

All fair enough when talking about keel boats. But on a Moth (the opening post refers to small high performance boats/moths) windage is a definate factor when going upwind at 16knots... low drag is crucial. Also as the rig is either upright or heeled to windward the grams saved between dyform & dyneema are not quite as critcal.
[/quote]


Yeah, Not sure where the windage cost/weight benefit lines cross. The Moths probably present the biggest challenge for windage as the frontal area of the rigging is a bigger percentage of the windage of the overall craft (since the craft is so small anyway). We have rigged alot of fast multihulls, formula 40's, supercats, etc and they still see the weight savings over the extra windage.

For the moth how much faster can you get on plane due to the weight savings versus the windage hit? The Steel (dyform) rigging is so small the weight saving going to synthetic might not present a big enough reduction.

John Franta, Colligo Marine

[jfranta]

Any clues on how to measure rig tension on PBO rigging? Can you just bung the Loos guage on it or will that damage the stay? Does loos just measure tension regardless of substrate or is it only for wire stays?

Cheers,

The Loos cals will be different for PBO as they are different for Rod and wire.

We have loos cals for Dux now for this purpose. They will be published soon.

John Franta, Colligo Marine.

[Fishingmickey]

Hello John,
Couple of questions for ya. You said: We design our rigs for 0.1 inches of creep per year (1 inch in 10 years). What length was the Dux you tested on the 7mm @ 500 lbs? Also how much creep do you think would you see in the spliced sections (top and bottom say 7mm 12" long splices).
Thanks,
FM

[RobG]

All fair enough when talking about keel boats. But on a Moth (the opening post refers to small high performance boats/moths) windage is a definate factor when going upwind at 16knots... low drag is crucial. Also as the rig is either upright or heeled to windward the grams saved between dyform & dyneema are not quite as critcal.

Agree with windage, you seem to have not added apparent into that - if you're doing 16kn upwind then there's probably over 20kn of breeze so apparent is over 30kn. Not so critical downwind where apparent is greatly reduced.

My main goal in reducing the mass of the rig was to reduce momentum. If I could save 300g that would be nice, but it seems I need to go to 4mm stays to minimse stretch (and handle carefully so as to not open the weave and reintroduce construction stretch when derigged). It will probably work for those who keep their boats rigged and can just tension it each time before sailing.

Dyform looks interesting, do you have a local (east coast Aus) supplier?


--
Rob

[jfranta]

Hello John,
Couple of questions for ya. You said: We design our rigs for 0.1 inches of creep per year (1 inch in 10 years). What length was the Dux you tested on the 7mm @ 500 lbs? Also how much creep do you think would you see in the spliced sections (top and bottom say 7mm 12" long splices).
Thanks,
FM

The 7 mm @ 500 lbs is calculated for a 50 foot length. Shorter length would obviously be less creep.

Creep is a material property and is not restricted to the splice ends. You might be asking about the constructional reset of the braid in the splice. For 7 mm, once the splice is reset at 10% of MBL the splice section gets about 1.5 inches shorter for a 19 inch bury. You need at least a 19 inch bury in 7 mm dyneema to retain 100 % of the breaking strength, 12 inches is too short.

John Franta, Colligo Marine

[killerken]

Hello John,
Couple of questions for ya. You said: We design our rigs for 0.1 inches of creep per year (1 inch in 10 years). What length was the Dux you tested on the 7mm @ 500 lbs? Also how much creep do you think would you see in the spliced sections (top and bottom say 7mm 12" long splices).
Thanks,
FM

The 7 mm @ 500 lbs is calculated for a 50 foot length. Shorter length would obviously be less creep.

Creep is a material property and is not restricted to the splice ends. You might be asking about the constructional reset of the braid in the splice. For 7 mm, once the splice is reset at 10% of MBL the splice section gets about 1.5 inches shorter for a 19 inch bury. You need at least a 19 inch bury in 7 mm dyneema to retain 100 % of the breaking strength, 12 inches is too short.

John Franta, Colligo Marine

hey guys, just a general response to the PBO thing.
I've been using it for years, on my old rules IC and on my current rocketship Chis Maas IC.
I've been having a real hard time finding it, because all kinds of know it alls have pretty near blabbed it out of existence.
I have been using 1/8" PBO with just a kind of graphite looking coating, from APS, and some coated in some kinda urethane from a secret west coast stash in some Glaser Cat's garage.
failing load was reported to be 4000 lbs. Chis and I have tested it to the mid 3000's with overly casual eye splices. all failures were at the end of the tapered bit fed up the middle void in the line, like a water ski tow rope. we found it necessary to very carefully make a long taper, down to a tapered single strand, to get max strength.
it is kind of a moot point on a Moth or Canoe as it would appear our shroud loads are nowhere near 4000lbs., even slamming down off big waves upwind.
none of us leaves a Moth or IC rigged in the sunlight all summer, as they get beat up or blown over in the dinghy park.
even if I had to change my shrouds once a week, I'd run the PBO. just weighing shrouds alone, on a pretty short Canoe mast, my PBO shrouds were close to two pounds lighter than Chris' wire shrouds.
a couple of pounds up a 20 foot mast has pretty good leverage. the light rig lets the hull get through waves much better, and easier to flick upright if you are sluggish in your responses...
the only fussy thing seems to be abrasion, from the threads on a screwed in pin on a shackle, or a bolt head, and so on.
stretch seems less than wire, and much less than any other kind of line I have tried.
I love splicing and working with it. even use it in some moving tackles like the vang and shroud tension cascades.
just buy it, rig it, and rip it ! taper your splices exquisitely though, chaps.
Cheers, Kenny

[Speng]

One thing you should note is that as John pointed out he typically sizes Dux for creep so you typically end up with a pretty high breaking load to design load factor. On boats with a lot of pretension (e.g. skiffs and a lot of sportboats) this means you end up with big shrouds = windage. OTOH if you don't carry a lot of pretension then you don't need to worry about creep too much especially if you derig after you sail in which case you could size the rig less for creep and more for stretch or strength greatly reducing rig diameter. IIRC moths don't carry a lot of rig pretension so you can go smaller. Even on a conservatively rigged boat the weight is on the order of 10% (not counting fittings) of wire

[quasi-expert]

I am looking into this topic over the winter as we are thinking about changing our rigging. I am especially interested in Dyneema, because of the price, maintenance and longevity in the marine environment.
So far the consensus seems to be that it cannot be used for boats where the rig is taken down frequently during the season, because of returning stretch and creep.
What about boats (let's say 8m, 1500kg) that stay in the water with the rig up all season? Will a regular check be enough or will I have to adjust the shroud tension everytime I want to go sailing or even while sailing?
I also saw an ad from someone who had modified an FT10 with dyneema shrouds. Anybody ever heard about the outcome of this experiment?

edit:
some months ago there were also pics of full dyneema rigging for a mini, any first hand experiences there?

I am also thinking about changin the hanks of our racing sails to small dyneema shackles (~3mm). Anyone using this on a wire or dyneema forestay? is chafe an issue?

[Gouvernail]

don't forget your tension guage!!

Attached Files

•  tension guage.jpg   135.78K   57 downloads

[steveromagnino]

"On campaigned sportboats we would probably use 9 mm dux that can handle about 1200 lbs of constant load (pretension) at 0.1" per year creep. So going from 6.4 mm (1/4 inch) in diameter to 9 mm for a slight increase in windage. In the 9 mm scenario you would now have a rig that stretches less so you would need less pretension than the wire had. We have successfully rigged many diamond stays which have very high relative pretension, constantly, so presents a good challenge for Dyneema derived rigging."

Interesting, so it was an issue that the size simply wasn't enough. We normally run 4mm dyform, and the dyneema we tested was IIRC 6mm or 7mm, maybe needed to be 8 or 9mm; that's starting to get big windage wise, but in a boat that weighs 350kg about, and carries a 108kg keel, the windage is probably less important than the righting moment and weight aloft. It required continuous retensioning, so maybe was simply too small.

On a typical 6.5m sportsboat twin spreader modern rig, we would probably be talking about pulling 4-6kg of rig weight out unless all the hardware changes as well, so then it starts to become a bit of a questionable decision as you need to be able to precisely adjust (so lashings aren't quite as good as turnbuckles) from race to race, condition to condition. I should take a set of scales and weigh to be sure.

Sporties (in our case) only do 6.5-6.7 knots upwind so windage running on apparent uphill isn't such an issue, we are sailing on apparent at 12-20 knots downhill though, when the windage might start to matter. Still think the gain from pulling weight out would offset it though.

[RobG]

Sporties (in our case) only do 6.5-6.7 knots upwind so windage running on apparent uphill isn't such an issue, we are sailing on apparent at 12-20 knots downhill though, when the windage might start to matter. Still think the gain from pulling weight out would offset it though.

I think you have that backwards. If you're doing 15kn downhill in 20kn of breeze then the apparent is much less than doing 6.5kn upwind in the same breeze. Windage matters more going to windward than downwind.

[Presuming Ed]

Windage matters more going to windward than downwind.

Is that still true for apparent wind boats? If the apparent is always forward of the beam, isn't minimising windage at all times a good idea?

[RobG]

Windage matters more going to windward than downwind.

Is that still true for apparent wind boats? If the apparent is always forward of the beam, isn't minimising windage at all times a good idea?

Yes, but there are trade–offs. The increased windage might be a reasonable price to pay for getting 10kg out of the rig provided the stretch and creep issues can be solved..

On a Moth, I decided to stick with SS wire. Synthetics have both windage and stretch problems that out–weigh the rig weight benefit, I really couln't see myself adjusting the tension on the water. A friend who has Dyform shrouds thinks they're a PITA (it's stiff and hard to work with) for the small reduction in stretch, though John Harris (former Moth world champion) uses it. I have much better things to spend money on than PBO and C6 shrouds, though they look dead sexy and probably matter at the very pointy end of the fleet.

Rob.

[Daniel Holman]

It seems to me that we are slowly closing in on the holy grail of non ferrous rigging, which I think can be described as a rigging which is affordable (both in material cost and DIY potential for terminations I.e splicing), robust (in terms of UV and wear resistance, and meets performance standards.

In the old days, dyneema had a similar breaking load to dyform of an equivalent diameter, but unfortunately was far stretchier (lower modulus). This doesn't matter in dock trim, ie static. The problems come in a dynamic environment where under an equivalent acceleration, the dyneema would stretch far more than dyform of equivalent diameter - therefore more head stay sag etc, nasty.
I think that "vanilla" dyneema also had creep issues - ie apply rig tension at dock, go for a coffee and come back to find less rig tension. 
Uv performance is also a worry.

Fast forward to today, and we have some rope vendors heavily touting exotic braided dyneema variants. 

It seems to me that, as long as you have adjustable standing rigging (for initial bedding in) then there is little reason not to go for it (we will gloss over soft attachments to masts for now) 

I seem to remember checking that sk78 max or equivalent has a similar modulus and breaking strain to dyform, so like for like diameters can be specified with equal windage for a massive weight saving.
The pre stretched heat treated cordage apparently has zero (mechanical) creep, and has a renewable uv coating so may need replacement every year or two, but nothing too onerous. 
It is a braided rope so robust and versatile when off the boat.

I expect / accept that if I take the rig out and coil the shrouds, and on first splicing the stuff will bed down, however after the first few sails and with the mast left up, it should all be fine and repeatable.
When putting the rig up, it should all be within the scope of the purchases. 

Aside from making sure that the spreader ends etc are suitable, I can't help but think there are few arguments against it in a dinghy with some adjustability in shrouds.

I know a guy with homemade 3mm sk78 (I think) shrouds and forestay on an i14 - he says that it is fine as long as they are set on tension rather than to calibration marks ( more so presumably on a full rig up , rather than mast up) 

I am sorely tempted to get involved. 

It seems to me that we are slowly closing in on the holy grail of non ferrous rigging, which I think can be described as a rigging which is affordable (both in material cost and DIY potential for terminations I.e splicing), robust (in terms of UV and wear resistance, and meets performance standards.

In the old days, dyneema had a similar breaking load to dyform of an equivalent diameter, but unfortunately was far stretchier (lower modulus). This doesn't matter in dock trim, ie static. The problems come in a dynamic environment where under an equivalent acceleration, the dyneema would stretch far more than dyform of equivalent diameter - therefore more head stay sag etc, nasty.
I think that "vanilla" dyneema also had creep issues - ie apply rig tension at dock, go for a coffee and come back to find less rig tension. 
Uv performance is also a worry.

Fast forward to today, and we have some rope vendors heavily touting exotic braided dyneema variants. 

It seems to me that, as long as you have adjustable standing rigging (for initial bedding in) then there is little reason not to go for it (we will gloss over soft attachments to masts for now) 

I seem to remember checking that sk78 max or equivalent has a similar modulus and breaking strain to dyform, so like for like diameters can be specified with equal windage for a massive weight saving.
The pre stretched heat treated cordage apparently has zero (mechanical) creep, and has a renewable uv coating so may need replacement every year or two, but nothing too onerous. 
It is a braided rope so robust and versatile when off the boat.

I expect / accept that if I take the rig out and coil the shrouds, and on first splicing the stuff will bed down, however after the first few sails and with the mast left up, it should all be fine and repeatable.
When putting the rig up, it should all be within the scope of the purchases. 

Aside from making sure that the spreader ends etc are suitable, I can't help but think there are few arguments against it in a dinghy with some adjustability in shrouds.

I know a guy with homemade 3mm sk78 (I think) shrouds and forestay on an i14 - he says that it is fine as long as they are set on tension rather than to calibration marks ( more so presumably on a full rig up , rather than mast up) 

I am sorely tempted to get involved. 

[High Flow]

i double that

[Fishingmickey]

Howdy Y'all,
I've been using synthetic rigging for about 5 years now on my Contender. I started with 3mm Vectran. I feel I've had pretty good success with it. I did see some of the creep issues mentioned. Once I got the creep out the repeatability of my settings was pretty decent. I've changed a couple of things in my construction technique. The last set of shrouds I made I went to 4mm Vectran and preloaded & stretched the shit out of the line by using a come-a-long and loading it up to 30-32 on my Loos gauge. I'd like to see how much better the prestretched and heat treated Dyneema Dux is verse's Vectran. But price wise and strength wise the Vectran in 4mm is plenty strong enough for the Contender..
Adios for now,
FM

[wildtsail]

As mentioned, Marlow does offer D12 Max which is super pre-stretched dyneema very similar to Dux and the pricepoint is actually a bit more affordable. D12 Max is offered down to 2.5mm in SK78 and SK90. There are a few dealers stocking this specific product and any of the many marlow dealers can order it.

[Daniel Holman]

Am I right in saying that 78 has lower modulus (ie greater elastic stretch for a given load and diameter) but better creep characteristics (ie won't plastically elongate so much under a sustained loading) than 90?
Dan

[Daniel Holman]

Am I right in saying that 78 has lower modulus (ie greater elastic stretch for a given load and diameter) but better creep characteristics (ie won't plastically elongate so much under a sustained loading) than 90?
Dan

[BalticBandit]

Windage matters more going to windward than downwind.

Is that still true for apparent wind boats? If the apparent is always forward of the beam, isn't minimising windage at all times a good idea?

Yes, but there are trade–offs. The increased windage might be a reasonable price to pay for getting 10kg out of the rig provided the stretch and creep issues can be solved..

Actually even downwind on an AWA boat with wind FWD of the beam, the math says that upwind will be the gating factor. Consider a boat sailing at 18knots in 10 knots of true at TWA of 146.

Wind will be directly abeam at an AWS of 14. BUT the vector component in the AFT directly will only be SEVEN knots of breeze


And the deeper you go, the less adverse drag you get. You only get increased drag if it is really light wind and you are shy reaching at say 95 TWA and 50 AWA

[The Black Pearl]

I used the Southern Spars C6 on my Moth last year. Long story on how I got it including a broken mast but anyway I digress. Set it up at home and took it to the Gorge. For one glorious practice day it was truly awesome. Felt like the boat would just accelerate in the gusts like nothing else. Very connected. Then rigging up next day a gust caught the mast and snapped the forsetay in an instant. I still think its great, just have never use it again due to the difficulty rigging. May be, some day its still in the box!

[steveromagnino]

Sporties (in our case) only do 6.5-6.7 knots upwind so windage running on apparent uphill isn't such an issue, we are sailing on apparent at 12-20 knots downhill though, when the windage might start to matter. Still think the gain from pulling weight out would offset it though.

I think you have that backwards. If you're doing 15kn downhill in 20kn of breeze then the apparent is much less than doing 6.5kn upwind in the same breeze. Windage matters more going to windward than downwind.

I don't mean the amount of windage from apparent, I mean the effect of it; sailing downwind in semi planing conditions the difference of planing and not planing is 4-5 knots; upwind the effect of windage might be 0.1 knot, even though the apparent is greater.

So anything that affects the planing threshold (windage) is a lot more expensive, even though you spend more time sailing upwind (at which time the weight savings probably are more substantial since you need to hike the boat flat upwind; downwind in w-ls we are not hiking most of the time once up and planing.)

But none of this is based on anything other than guesses.