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Old 18-10-2018, 11:13   #1
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Dyneema rigging fittings?

The only two brands I can find regarding dyneema rigging, is Colligo and Blue wave. Are there any other ones I have missed?

Seems there has been a lot of talk about how big radius dyneema needs to not be downgraded, but not really any answers. Colligo seem to have 5:1 radius and Blue wave's looks a lot smaller with their stainless fittings.

How about skip all those fancy fittings and splice directly to a turnbuckle's clevis pin? Or any other DIY solutions?

I was thinking going with a DM20, either 8 or 10mm.
Today the rigging is 1x19, 1/4" or if it was 9/32...
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Old 18-10-2018, 12:17   #2
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Re: Dyneema rigging fittings?

At the least I'd use wire rope thimbles, the ones that are one continuous piece. Available on the internet at fairly good prices. Bending the line around the pin of a turnbuckle without a thimble seems to be way too tight a radius.
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Old 26-10-2018, 14:53   #3
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Re: Dyneema rigging fittings?

I've used these ones in the past, albeit only on small boats (< 24 ft)



They are of a closed design and in cross-section are oval shaped, which from what I am led to believe is required for dyneema.



Closed stainless steel rope thimble


Very inexpensive when compared to Colligo, but then again what price would you place on knowing your mast is secure.
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Old 26-10-2018, 15:40   #4
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Re: Dyneema rigging fittings?

Quote:
Originally Posted by roverhi View Post
At the least I'd use wire rope thimbles, the ones that are one continuous piece. Available on the internet at fairly good prices. Bending the line around the pin of a turnbuckle without a thimble seems to be way too tight a radius.

Actually, the open ones are for wire rope. The open ends can't cut wire rope.



The closed ones are called sailmaker's thimbles. There are also tube thimbles.
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Old 27-10-2018, 17:23   #5
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Re: Dyneema rigging fittings?

The bend radius was a huge issue for SK90 Dyneema, which everyone has phased out since SK99 came out. Apparently both SK78 and SK99 can take a tighter radius than 90 could. I'd still not just splice to a pin, but a thimble that will fit the line's diameter should be a large enough bend radius. Unless someone sells you their last spool of 90 cheap.
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Old 06-08-2019, 07:03   #6
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Re: Dyneema rigging fittings?

Who has successfully used sailmakers thimbles on standing rigging of larger sailboats?
thanks
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Old 06-08-2019, 11:07   #7
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Re: Dyneema rigging fittings?

Quote:
Originally Posted by andreas.mehlin View Post


(...)


I was thinking going with a DM20, either 8 or 10mm.
Today the rigging is 1x19, 1/4" or if it was 9/32...

Did you assume straight pull for Dyneema material?


If so, wrong.


Read on how much is lost in bending the material. For it is over 70% loss in a bowline bend.


Now look at BlueWave fitting and see how tight the turn is?


...




My opinion : use a fitting with the highest turn radius (unless you have a proper straight pull fitting for Dyneema (if so, pls share the link)


I remember seeing (Coligo ???) large radius fittings on one very very pro equipped maxi yacht ...



Cheers,
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Old 06-08-2019, 19:50   #8
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Re: Dyneema rigging fittings?

Well, wrong...

Yes you loose in a bend, but the bend (splice) have two "sides", one on each side of the bend...

Several tests have been made and published (I think here on CF and other forums). If you go with a 1:1 ratio bend (10mm dyneema over 10mm clevis for instance)...there is a 10-15% weakening of the line.



Quote:
Originally Posted by barnakiel View Post
Did you assume straight pull for Dyneema material?


If so, wrong.


Read on how much is lost in bending the material. For it is over 70% loss in a bowline bend.


Now look at BlueWave fitting and see how tight the turn is?


...




My opinion : use a fitting with the highest turn radius (unless you have a proper straight pull fitting for Dyneema (if so, pls share the link)


I remember seeing (Coligo ???) large radius fittings on one very very pro equipped maxi yacht ...



Cheers,
b.
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Old 07-08-2019, 08:22   #9
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Re: Dyneema rigging fittings?

Quote:
Originally Posted by andreas.mehlin View Post
Well, wrong...

Yes you loose in a bend, but the bend (splice) have two "sides", one on each side of the bend...

Several tests have been made and published (I think here on CF and other forums). If you go with a 1:1 ratio bend (10mm dyneema over 10mm clevis for instance)...there is a 10-15% weakening of the line.

+1!


If according to tests the loss is only 15% on a 1:1 bend this makes me only happier. The 70% figure I took from SVB tests.



The BW terminal I had in hand was about 6mm. The pin looked very wee, but possibly 6mm or thereabouts.


The 'double material' on each side does nothing to the strength of the thing as the failure happens at the weakest point (the bend).



Do you happen to remember how many repetitive loaded pulls were applied in the test? I just hope it was not a one pull test as some of the applications undergo repetitive pulls at millions of cycles (e.g. standing rigging on a boat under way).


Tanks for feedback. Most appreciated!


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Old 07-08-2019, 08:54   #10
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Re: Dyneema rigging fittings?

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Originally Posted by barnakiel View Post
The 'double material' on each side does nothing to the strength of the thing as the failure happens at the weakest point (the bend)
B, you are simply wrong about this. It is extensively documented and tested.

In a spliced loop the loading on the strands in the loop is 1/2 the loading on the standing part. It is double strength. So, while a 1:1 bend very roughly cuts the strength by (a bit more than) 50%, the loop starts out at 200%, so it ends up near (a bit less than) 100% (of line strength) with a 1:1 bend.

This is entirely different than say a working line over a sheave, although people (even supposedly informed people) confuse the two cases all the time.

You are correct that fatigue is a separate matter. But is is also significantly more of a problem with a working line over a sheave than a static loop.
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Old 07-08-2019, 17:56   #11
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Re: Dyneema rigging fittings?

BIG thanks for explaining this.


We learn every day. Also the old ones.


I am looking into replacing our waterstay with synthetic wire soon. Now it is ss wire but I am moving it higher to allow for a chain hook below the stay. If I use ss again I need to go to the rigger and have things swaged. It is OK but then not repairable onboard.



I'd rather use synthetic wire there as then I can build it all in house. And also replace or renew in any place of the world. When we sail, it always to odd places off the beaten track.



Cheers,
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Old 08-08-2019, 18:18   #12
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Re: Dyneema rigging fittings?

Defenders has cast ss thimbles by suncor they say are good for amsteel might work for you? Item# 003005
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