[jdege]

I have a 37' Herreshoff Meadowlark that needs new standing rigging, and I'm looking for advice on what to do, and for feedback on decisions made. I'm going to have a number of questions, and rather than tossing them all into a single post, I thought I'd ask them one at a time.

My boat is a ketch, with fairly short (28'6" main) masts in tabernacles. I can raise and lower them single-handed and likely will at least once per season.

Question 0, of course, is whether to replace with steel or synthetic. I've decided on synthetic for a number of reasons.

Question 1, then, is which synthetic?

I'm leaning towards Colligo Dux because they seem to have the most experience with synthetic rigging, and their explanations of why they've stayed with the older formula Dyneema seem solid.

I may or may not use Colligo's hardware, it's quite pricey, but that's an issue for future questions.

Right now, the question is what size to use.

If this was a production boat I could look up what size to use, but it's not. The best I can figure is to size based on the existing steel rigging.

The existing shrouds, forestays, and triatic stay are 3/16", the running backstays are 1/8".

I see no reason to retain the complexity of having two different sizes. 3/16" is 4.8mm. Colligo recommends sizing based on equivalent stretch, rather than strength, and lists Dux size 6 as equivalent to 5mm. But if you go into their online shop, they sell Dux in 5mm and 7mm.

So I'm thinking on using 7mm Dux, which should be far stronger and less stretchy than the steel wire I'm replacing.

Thoughts?

 

[paulk]

Sometimes rigging is made in different sizes on purpose, so that IT breaks before something else does. Using an exaggerated example, in a pitchpole situation it might be better to lose the mast by having the backstays break than to have the backstays be so strong that they rip out the chainplates and carry away the stern quarters of the boat.

 

[jdege]

Sometimes rigging is made in different sizes on purpose, so that IT breaks before something else does. Using an exaggerated example, in a pitchpole situation it might be better to lose the mast by having the backstays break than to have the backstays be so strong that they rip out the chainplates and carry away the stern quarters of the boat.

If that were a design consideration, I'd rather have a designed break-away point in the termination fittings than to have the line break at some arbitrary point.

My guess is that the backstays are 1/8" rather than 3/16" solely because the backstays have to be stowed away, and the thinner wire is easier to handle. Even 7mm Dyneema is easier to handle than wire, so I don't see the need.

The previous owner told me he never bothered to set the backstays. And for the lake sailing he did, he probably didn't need them.

 

[Minnewaska]

I may or may not use Colligo's hardware, it's quite pricey

Just my two cents. I'm not familiar, but I'd be sure to get quality hardware that was purpose designed. Partly, because you'll need to continue to adjust for stretch over the life of the rigging, as I assume you've researched. Secondly, because synthetic rigging is a bit controversial. Some may think of it as a budget move, more than a quality one. Of course, the weight argument would counter a bit. The point is, I would not want to make the hardware look like a kludge and give solely the discount impression, if I was trying to sell the boat.

 

[Jeff_H]

Rigging is engineered for the loads that they need to deal with and the amount of stretch that they are expected to be able to tolerate and pass onto the other components of the rig. (nags, chainplates, etc.) Oversizing standing rigging is rarely a good idea since in theory that imparts higher loadings into the other elements of the rig that they were not necessarily designed to resist. The cyclical higher loadings can do damage over time.

Jeff

 

[jdege]

Rigging is engineered for the loads that they need to deal with and the amount of stretch that they are expected to be able to tolerate and pass onto the other components of the rig.

So I should try to match the stretch of the existing rig, and not make it significantly stiffer.

Colligo's charts give 6mm SK75 as equivalent stretch, but they don't sell 6mm, only 5mm or 7mm.

Other vendors don't sell SK75 at all, they've replaced it with SK78. But I can find 6mm SK78.

SK78 is supposed to have reduced creep, but does it have the same stretch?

 

[Killick]

Call John Franta at Colligo - he will talk at length about your options. I'm in the process of rerigging my Contest 31 now with dux and am going to go with Colligo's thimbles with Hayn turnbuckles. Others have used lashings on larger boats such as yours: Andy Schel rerigged his 36' ketch with lashings and there is a guy on youtube named Herb Benavent (The Rigging Doctor) who has I think like a 45' boat with lashings. (Franta says 30' is the max for lashings, not sure why. He doesn't say.) Benavent is a rigger and has a lot of miles on his setup and while I'm sure it works, it looks very bodged together, with open stainless thimbles, etc. Lashings are dirt cheap and bull strong - easy to adjust and are perfect for DIY, and Colligo makes lashing "deadeye" thimbles. I think there is more than one way to skin this cat. But I'm going to use the far superior Colligo thimbles as a buy once/cry once option. They can't fail and there is never a need to upgrade.

Dux is of course sized for stretch, not for strength, you know this. My standing rigging is all 1/4" except for the twin back stays which are like 5mm or something. It's a heavily built boat for a 31', that's the same size they used on a Westsail 32 which weighs over twice as much. My cap shrouds will be 9mm and lowers and backs will be 7mm. For now I'm leaving a stainless forestay on as I've converted to hank on headsails. Others have used a dyneema forestay with hanks and the hanks wear faster than the forestay they say.

As as aside, there are lots of videos on youtube of "sailing fails" - fun to watch in your idle hours. Many videos of boats sailing into bridges and ships, etc., and as far as I can in not a single one of these does the standing rigging fail - the mast always buckles first. I'm concerned about the insanely strong rig forces transferring force down to my 50 year old chainplates which I'm sure would be ripped right out of the deck in some tragedy - so now I'm looking at new external chainplates as a fix. You "fix" one thing, and then you have to "fix" everything downstream.

As for the failure mode on dyneema, the first is friction (avoidable with forethought) and the second is UV exposure. I believe the depth of damage to dyneema from UV is less than a micron - after that it gets a sort of protective sunburn and damage stops. Your rig will be probably 3 x stronger than stainless so this can't be considered an issue. The big problem is (as has been said) what will break when the rigging doesn't, because it will not, if you do your splices correctly. Probably mast fittings or chainplates, neither of which is an easy fix.

 

[jdege]

Franta says 30' is the max for lashings, not sure why. He doesn't say.

I have to figure it's a matter of how much force you need to apply to to get the proper tension, and I have to think that's more a matter of how long is the shroud then how long is the boat.

Curlew is 37' overall, but she's a ketch with fairly short masts.

 

[Killick]

I'm sure this is a big part of it.

 

[Jeff_H]

I have to figure it's a matter of how much force you need to apply to to get the proper tension, and I have to think that's more a matter of how long is the shroud then how long is the boat.

Curlew is 37' overall, but she's a ketch with fairly short masts.

If the assumption is that the original rigging was sized properly, then you would want reverse engineer to use a Dyneema line with similar stretch characteristics to the stainless steel that it replaced. If a corresponding sized Dyneema does not exist, then you may be forced to use a larger size. In an ideal world, you would then want to increase the tangs and chainplates and their bolts accordingly.

Jeff

 

[jdege]

If the assumption is that the original rigging was sized properly, then you would want reverse engineer to use a Dyneema line with similar stretch characteristics to the stainless steel that it replaced.

Do you know where I can find stretch data for 1×19 SS, SK75, and SK78?

 

[jdege]

So, according to this: Stainless Steel Wire Rope Technical Information

Elastic stretch can be calculated by the following formula:

Elastic Stretch = (W x L) / (E x A)

W = Applied Load ( kN )
L = Cable length ( mm )
E = Strand Modulus ( kN/mm²)
A = Area of Cable = (D2 x pi) / 4 (where D= Dia of cable mm)
Typical values for E are:

1x19 = 107.5 kN/mm²
7x7 = 57.3 kN/mm²
7x19 = 47.5 kN/mm²
Dyform = 133.7 kN/mm²

So, next to find the Strand Modulus for SK75 and SK78.

 

[FTLSailor]

I have a 37' Herreshoff Meadowlark that needs new standing rigging, and I'm looking for advice on what to do, and for feedback on decisions made. I'm going to have a number of questions, and rather than tossing them all into a single post, I thought I'd ask them one at a time.

My boat is a ketch, with fairly short (28'6" main) masts in tabernacles. I can raise and lower them single-handed and likely will at least once per season.

Question 0, of course, is whether to replace with steel or synthetic. I've decided on synthetic for a number of reasons.

Question 1, then, is which synthetic?

I'm leaning towards Colligo Dux because they seem to have the most experience with synthetic rigging, and their explanations of why they've stayed with the older formula Dyneema seem solid.

I may or may not use Colligo's hardware, it's quite pricey, but that's an issue for future questions.

Right now, the question is what size to use.

If this was a production boat I could look up what size to use, but it's not. The best I can figure is to size based on the existing steel rigging.

The existing shrouds, forestays, and triatic stay are 3/16", the running backstays are 1/8".

I see no reason to retain the complexity of having two different sizes. 3/16" is 4.8mm. Colligo recommends sizing based on equivalent stretch, rather than strength, and lists Dux size 6 as equivalent to 5mm. But if you go into their online shop, they sell Dux in 5mm and 7mm.

So I'm thinking on using 7mm Dux, which should be far stronger and less stretchy than the steel wire I'm replacing.

Thoughts?

View attachment 141344 View attachment 141344

I have a 1975 Pearson 419 center cockpit ketch (42'). I opted for Colligo Dux, with their terminators and Hayn turnbuckles. John and his assistants worked with me and we created a document outlining each shroud with its proper length as a spec for the creation of my standing rigging. They applied their expertise as to the type of Dyneema and I was more than happy to have them do so - they are the experts. I supplied the measurements and we discussed the termination options together. Colligo is a VERY professional crew. I am sure that as your work with them, you will experience this. On their site are some documents that should help you get started in your documentation.