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Old 19-08-2023, 10:42   #286
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Youíve lost me. You said you were gonna use 9mm pre-stretched and heat set Dyneema and I did the math.

Now you say itís 6mm?

Also, you donít do 10-15% of the breaking strength of the shroud; you do 10-15% of the load where for steel wire they do 30-50% . This is to cope with creep.

I had calculated three loops was okay but it seems we first need to make sure what size wire your shrouds are and what size/type Dyneema is used.
Thanks for posting. I have been going through this all day here.

I think I have wandered off the path somehow.

The roll for my halyards is 9mm. The roll for the lashings (loops now) is 6mm.


I was not doing anything with the shrouds at all. I was doing 10 to 15% of the breaking strength of the dyneema. My righting moment is 14,000lbs so thatís what I have to be able to cope with. Thatís the maximum load on the dyneema and the shroud (itís the same load for both).

So if the 6mm is 8,360lbs breaking strength and the load is 14,000lbs, but I can only use 15%, I can only get 1254lbs per leg of dyneema. 14,000/1254 is 11.16 or 12 legs of dyneema. Since there are 2 legs per wrap. Thatís 6 wraps of 6mm for EACH shroud, so 12 wraps in total for 2 shrouds. I can only fit 6 wraps of 6mm maximum on the pin.

If I try to use the 9mm: 23,320lbs x .15 is 3,498. Thatís 4 legs or 2 wraps to get to 14,000lbs. Doable. But 2 stays so 4 wraps total on the pin. Doable.

A bummer though because i will have to waste halyards on that. I guess I can order more 9mm dyneema.

Maybe there is somewhere I can use the 6mm, 8,360lbs stuff. Maybe as a topping lift? Maybe for sheets?
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Old 19-08-2023, 11:33   #287
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Thanks for posting. I have been going through this all day here.

I think I have wandered off the path somehow.

The roll for my halyards is 9mm. The roll for the lashings (loops now) is 6mm.


I was not doing anything with the shrouds at all. I was doing 10 to 15% of the breaking strength of the dyneema. My righting moment is 14,000lbs so thatís what I have to be able to cope with. Thatís the maximum load on the dyneema and the shroud (itís the same load for both).

So if the 6mm is 8,360lbs breaking strength and the load is 14,000lbs, but I can only use 15%, I can only get 1254lbs per leg of dyneema. 14,000/1254 is 11.16 or 12 legs of dyneema. Since there are 2 legs per wrap. Thatís 6 wraps of 6mm for EACH shroud, so 12 wraps in total for 2 shrouds. I can only fit 6 wraps of 6mm maximum on the pin.

If I try to use the 9mm: 23,320lbs x .15 is 3,498. Thatís 4 legs or 2 wraps to get to 14,000lbs. Doable. But 2 stays so 4 wraps total on the pin. Doable.

A bummer though because i will have to waste halyards on that. I guess I can order more 9mm dyneema.

Maybe there is somewhere I can use the 6mm, 8,360lbs stuff. Maybe as a topping lift? Maybe for sheets?
No, sizing for creep isnít for peak loading but for static loading.

We still need to know the diameter of the wire of the shroudsÖ
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Old 19-08-2023, 11:38   #288
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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No, sizing for creep isn’t for peak loading but for static loading.

We still need to know the diameter of the wire of the shrouds…
Wow. That surprises me.

Because the maximum load is 14,000 pounds. Without looking at any shroud. I’m not even sure how one would calculate a static load. It makes very little sense to me because as the wind kicks in the load varies tremendously. Up to 14,000lbs when a hull begins to lift. The only static load varies based on how much you crank the turnbuckles. So I’m confused.

But the shrouds are 1/2” 1x19 wire.
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Old 19-08-2023, 11:44   #289
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Wow. That surprises me.

Because the maximum load is 14,000 pounds. Without looking at any shroud. Iím not even sure how one would calculate a static load. It makes very little sense to me because as the wind kicks in the load varies tremendously. Up to 14,000lbs when a hull begins to lift. The only static load varies based on how much you crank the turnbuckles. So Iím confused.

But the shrouds are 1/2Ē 1x19 wire.
Okay. The static load is what the rigger sets for pre-tension. My guess is he will set it to 20% of breaking strength.

We have the same size capshrouds It is regular wire, right, not Dyform? I currently have 12mm Dyform but plan to go back to 1/2Ē regular next replacement.

Let me check the math..
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Old 19-08-2023, 11:47   #290
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

Also, may be of importance or at least something I want to put in here:

There is just a single cap shroud (no lower) and it’s 7/16” in the plans for the boat. There are no lowers.

However, the mask that I bought, which actually has a higher set of moments, has a lower.

Just putting that in here.
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Old 19-08-2023, 11:49   #291
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Okay. The static load is what the rigger sets for pre-tension. My guess is he will set it to 20% of breaking strength.

We have the same size capshrouds It is regular wire, right, not Dyform? I currently have 12mm Dyform but plan to go back to 1/2Ē regular next replacement.

Let me check the math..
Yes. This is not Dyform Just regular.

Gotcha. The Rigger is probably me. From what I understand I just need to adjust it as I go sailing. I donít want the leeward shroud to get loose and slack. But I donít want to over tighten anything either.

Basically keep it all in column, make sure the Leeward shrouds are not getting slack.
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Old 19-08-2023, 11:54   #292
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

Wire breaking strength is 25,000lbs. Pretension will be 5,000lbs.

6mm Dyneema is 8,360lbs. One turn is 16,500lbs.

15% of 35,000 is 5,250lbs

35,000 / 16,500 = 3 loops.

So it stays three loops because I first thought you had 14mm shrouds and the rest goes into overbuilding this as you can see in my wild rounding to stronger above.

Letís check from the three loops starting-point: 3x 16,500 = 49,500lbs so thatís double of the wire and 3.5x your peak load.

15% of 49,500 = 7,425lbs which is 1.5x expected static load. Three turns will be fine.
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Old 19-08-2023, 12:04   #293
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Yes. This is not Dyform Just regular.

Gotcha. The Rigger is probably me. From what I understand I just need to adjust it as I go sailing. I donít want the leeward shroud to get loose and slack. But I donít want to over tighten anything either.

Basically keep it all in column, make sure the Leeward shrouds are not getting slack.
Did you get that book from Dedekam? It explains how to set pre-tension using a tape measure. Iím pretty sure the 20% is your ticket for the main capshroud, that goes all the way up.

The lower that you have is to keep the middle section of the mast straight. While sailing look up from the gooseneck along the track and you will see the midsection deflection, telling you what to tension more. The masthead will be good because of the pre-tension.

I recommend to first read the whole book for overview, then come back to the detail sections. Of course, being apprentice, I had this rigger talking to me the whole way which helped but later I compared everything we did with the book and I think itís pretty clear. You will never find your exact rig but you just go for the part you need for the rig that comes closest. The rake, bend etc. is all explained very well too.
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Old 19-08-2023, 12:34   #294
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Wire breaking strength is 25,000lbs. Pretension will be 5,000lbs.

6mm Dyneema is 8,360lbs. One turn is 16,500lbs.

15% of 35,000 is 5,250lbs

35,000 / 16,500 = 3 loops.

So it stays three loops because I first thought you had 14mm shrouds and the rest goes into overbuilding this as you can see in my wild rounding to stronger above.

Letís check from the three loops starting-point: 3x 16,500 = 49,500lbs so thatís double of the wire and 3.5x your peak load.

15% of 49,500 = 7,425lbs which is 1.5x expected static load. Three turns will be fine.

Following almost all of this. Just double checking that 35,000 comes from rounding 25,000 up?

I had better go read the book now. I think Iím at a point where I need to.

The good news is six loops will just barely fit onto the chain plate pin, but it will. And now I realize why my chain plate pin is so narrow. Because there was never supposed to be any lowers. There were only uppers in the design originally.

Iím going to take the rest of the afternoon to blast through as much of that book as I can.

Thank you for taking me through this. Itís definitely not quite the way I was picturing things would be derived.
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Old 19-08-2023, 13:10   #295
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

Well, that was a quick study.

After learning about the pre-tensioning methods, I saw why I don’t need running backstays. Finally. Something cleared that up. Everybody had been arguing back-and-forth about that in other threads.

The confusion was people trying to apply monohull ideas to a Catamaran.

With monohulls, you need swept back spreaders in order to have the shrouds sweet back. Obviously. Because they touch the spreaders.

With my boat, the shrouds sweep back (eliminating the need for running backs) but they do not touch the spreaders. The spreaders are only part of the double diamond arrangement on my boat. The double diamond arrangement keeps the mast in column athwartship and does nothing else.

Anyway, I think everything is fairly well set. The only thing is that little baby stay. Maybe there will be something in the book about that somewhere.

When I look back at my plans, they show three pieces of standing rigging. A forestay and two cap shrouds. Nothing else. There is also a self tacking jib.

That’s how the boat was designed.

So I am adding additional lowers into the mix here because my mast came with them. I wonder if they will even actually be needed. Time will tell I guess.
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Old 19-08-2023, 13:20   #296
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Well, that was a quick study.


....................................



I wonder if they will even actually be needed. Time will tell I guess.



Good approach. Eventually you'll stop wondering why it's still up and which part to blame for that.
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Old 19-08-2023, 13:36   #297
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Good approach. Eventually you'll stop wondering why it's still up and which part to blame for that.

The lowers are pretty weird.

Instead of not existing, like on the plans for the boat, they are tied in, 1/4 of the way into the top diamond. The top diamond starts pretty much at the uppers.

So they can’t bend much of anything really. Odd. Would like to figure those out eventually. They seem to do very little. It’s not like they can move the diamonds in and out of shape. That stays firmly in column. About 10 feet above them are the uppers. And that’s it.

Traditionally they are used to keep the mast in column. But that doesn’t happen on this rig. It’s already in column. The one thing they could be doing at that level is pulling aft a little bit. That’s it.
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Old 19-08-2023, 14:37   #298
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Following almost all of this. Just double checking that 35,000 comes from rounding 25,000 up?

I had better go read the book now. I think Iím at a point where I need to.

The good news is six loops will just barely fit onto the chain plate pin, but it will. And now I realize why my chain plate pin is so narrow. Because there was never supposed to be any lowers. There were only uppers in the design originally.

Iím going to take the rest of the afternoon to blast through as much of that book as I can.

Thank you for taking me through this. Itís definitely not quite the way I was picturing things would be derived.
The 35,000 is the number where 15% of it is more than the 5,000 lbs static load.
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Old 19-08-2023, 15:57   #299
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Martingale stay installed. Took 20 mins since I requested the bushings a little large to get a perfect fit. Ground the OD on them to fit

Want to start an Advanced Catamaran Anchor Roller thread? Iíll start it by suggesting you incorporate the anchor roller into the longeron and deploy/store your anchor under your front beam. Hereís a teaser of our setup.
Click image for larger version

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Old 19-08-2023, 16:01   #300
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Want to start an Advanced Catamaran Anchor Roller thread? I’ll start it by suggesting you incorporate the anchor roller into the longeron and deploy/store your anchor under your front beam. Here’s a teaser of our setup.
Attachment 279809

Certainly. Go right ahead. Pardon me if I don’t go in there very often because I have too many pressing projects to do before I can begin looking at the non mission critical stuff.

I’d like to get sailing, fix all my hurricane damage and get an interior going before stuff like that.

In my case, the beam showed up after the anchor system was built to plan. Need to put some sacrificial pads down for now, but I’m not even doing that since I probably have another 6 anchor up/downs to do between now and April 2024
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