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Old 11-01-2020, 14:49   #1
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A method to determine tension in Dyneema rigging.

I’ve been searching the internet for ways to accurately determine tension on New England STS-HSR Dyneema to use as standing rigging. I saw mention on Colligo’s web page about converting tension using a Loos gauge and their conversion table (see attached image taken from Colligo site).

I am using 5 and 6mm NE STS-HSR to renew the 1x19 ss standing rigging on my boat and noted that 6 mm is not shown on the Colligo chart. Is the conversion applicable to STS or is it proprietary to Colligo?

The problem is how to determine when I’ve reached the magical 10% tension to re-seat the Dyneema yarns after splicing? I have a Loos gauge for 3/16 – 1/4” 1x19 and was figuring on making up a short pendant out of 3/16” 1x19 to anchor my come-a-long to and use my Loos gauge on the 1x19 pendant. Since the pendant will have the same tension as on the NE STS it should work, but would be much better to just be able to use the Loos gauge directly. Any other ideas???
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Old 11-01-2020, 20:45   #2
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Re: A method to determine tension in Dyneema rigging.

You don't want to go to 10%. Dyneema rigging is sized to get the right amount of creep, not strength. This results in larger diameter lines with breaking strengths way above shrouds made from steel wire or rod. Cranking a dyneema shroud up to 10% of its breaking strength may well break your boat. I've done a lot of rig tuning for offshore racing and I do not have a way to measure tension on dyneema shrouds. Just go sailing and tune it by feel. Head out in a good stiff breeze and adjust until the mast is where you want it on both tacks. A gauge is nice for repeatability, if you change things often and want to get back to where you had it previously, but it's not needed.


edit: I sort of mis-read your post. What I said stands, but as for re-seating after splicing, a measurement might be good. I don't know. I just tune 'em I don't make 'em.
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Old 11-01-2020, 21:27   #3
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Re: A method to determine tension in Dyneema rigging.

Maybe you could tension using a hydraulic jack with a pressure gauge? Easy to convert pressure to force.
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Old 12-01-2020, 03:04   #4
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Re: A method to determine tension in Dyneema rigging.

With 6mm you don't need huge hydraulic pressure to seat the splices: you can string the shroud between two trees as tight as possible, then yank sideways on the middle. A sudden violent deflection like that generates a lot of force. You can do it more gently by attaching a handy-billy to the center of your stretched-out span and cranking on that. If you have the luxury of a load cell, you can put that in the system (in line with the shroud, not the handy-billy).
The HSR is made of the same material as DUX, AFIK, so the Colligo charts ought to be fine.
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Old 12-01-2020, 09:55   #5
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Re: A method to determine tension in Dyneema rigging.

following. We've always "tuned" our 1x19 S/S wire rigging by feel and slack, and by looking up the mast to ensure it's straight and balanced. Just starting to learn about Dynema rigging....why did you chose to go that way?
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Old 12-01-2020, 12:18   #6
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Re: A method to determine tension in Dyneema rigging.

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Originally Posted by jt11791 View Post
I've done a lot of rig tuning for offshore racing and I do not have a way to measure tension on dyneema shrouds. Just go sailing and tune it by feel. Head out in a good stiff breeze and adjust until the mast is where you want it on both tacks.
Unfortunately I don´t have that kind of experience.
I would be scared to death going out in a stiff breeze and tune it by feel.
I might end up with the mast in the wrong place
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Old 12-01-2020, 13:21   #7
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Re: A method to determine tension in Dyneema rigging.

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Unfortunately I don´t have that kind of experience.
I would be scared to death going out in a stiff breeze and tune it by feel.
I might end up with the mast in the wrong place


If you feel like you can do it with a gauge, you can certainly do it without one. It's really not hard. Start at the dock getting the mast straight and in column, then go sailing. When sailing, your leeward shrouds will go slack, maybe very slack. Tighten them up and then tack over and do the same on the other side, counting turnbuckle turns to keep things even. Keep sighting up the mast to make sure it's straight on both tacks.
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Old 12-01-2020, 14:01   #8
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Re: A method to determine tension in Dyneema rigging.

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Originally Posted by jt11791 View Post
If you feel like you can do it with a gauge, you can certainly do it without one. It's really not hard. Start at the dock getting the mast straight and in column, then go sailing. When sailing, your leeward shrouds will go slack, maybe very slack. Tighten them up and then tack over and do the same on the other side, counting turnbuckle turns to keep things even. Keep sighting up the mast to make sure it's straight on both tacks.
First I thought we are talking about controlling tension on an ALL Dyneema rigging but now You are talking about turnbuckles.
Well, of course that is a different story and sounds a lot less intimidating.
THXs, I can see myself doing that. If I get the mast straight at the dock in the first place the rest is symmetric fine tuning with the turnbuckles eliminating the slack.
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