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18-10-2018, 11:13
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#1
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Registered User
Join Date: Sep 2009
Posts: 522
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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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18-10-2018, 12:17
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#2
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Moderator Emeritus
Join Date: Aug 2005
Location: Carlsbad, CA
Boat: 1976 Sabre 28-2
Posts: 7,505
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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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Peter O.
'Ae'a, Pearson 35
'Ms American Pie', Sabre 28 Mark II
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26-10-2018, 14:53
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#3
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Registered User
Join Date: Mar 2011
Posts: 640
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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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26-10-2018, 15:40
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#4
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Writing Full-Time Since 2014
Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 9,569
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Re: Dyneema rigging fittings?
Quote:
Originally Posted by roverhi
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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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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27-10-2018, 17:23
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#5
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Marine Service Provider
Join Date: Dec 2010
Location: Little Compton, RI
Boat: Cape George 31
Posts: 2,976
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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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Ben
zartmancruising.com
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06-08-2019, 07:03
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#6
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Registered User
Join Date: Nov 2014
Location: halifax, nova scotia
Boat: Cross 24 trimaran
Posts: 773
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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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Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance. Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life. VE0XYZ
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06-08-2019, 11:07
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#7
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Registered User
Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 20,420
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Re: Dyneema rigging fittings?
Quote:
Originally Posted by andreas.mehlin
(...)
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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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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06-08-2019, 19:50
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#8
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Registered User
Join Date: Sep 2009
Posts: 522
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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
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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07-08-2019, 08:22
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#9
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Registered User
Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 20,420
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Re: Dyneema rigging fittings?
Quote:
Originally Posted by andreas.mehlin
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.
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+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!
barnakiel
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07-08-2019, 08:54
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#10
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Registered User
Join Date: Apr 2019
Posts: 1,355
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Re: Dyneema rigging fittings?
Quote:
Originally Posted by barnakiel
The 'double material' on each side does nothing to the strength of the thing as the failure happens at the weakest point (the bend)
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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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07-08-2019, 17:56
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#11
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Registered User
Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 20,420
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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,
b.
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08-08-2019, 18:18
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#12
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Registered User
Join Date: Nov 2009
Location: lakeville ma.
Boat: corbin39
Posts: 150
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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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