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Old 24-04-2018, 12:46   #1
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Rope clutch and Dyneema line

Has any got any real life experience using Dyneema type "synthetic" line through a rope clutch? I am intending on installing 120 VAC electric hoists for my tender, and would like to be able to control the line paying out, if I have a power failure.
The hoists have a brake on them,and the ability to "free spool". If I experienced a power failure, I could lock the rope clutch, and free spool the hoist, then use the clutch to control the paying out in order to launch the tender.
Has anyone tried this? Any comments as to the feasibility?
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Old 24-04-2018, 13:12   #2
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Re: Rope clutch and Dyneema line

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Originally Posted by captain465 View Post
Has any got any real life experience using Dyneema type "synthetic" line through a rope clutch? I am intending on installing 120 VAC electric hoists for my tender, and would like to be able to control the line paying out, if I have a power failure.
The hoists have a brake on them,and the ability to "free spool". If I experienced a power failure, I could lock the rope clutch, and free spool the hoist, then use the clutch to control the paying out in order to launch the tender.
Has anyone tried this? Any comments as to the feasibility?
I've always covered the tails, since in my experience naked Dyneema is too skinny and too slippery to hold well. Controlling a line through a clutch is not very good either. Can you get the tail on a winch drum?

And how much help is it to lower the dinghy if you can't recover it? I figure out a way of taking the tails to a winch.
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Old 24-04-2018, 18:15   #3
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Re: Rope clutch and Dyneema line

Thinwater,
Thanks for your comments, since I have a trawler, with davits to carry the tender on the cabin top, I do not have any winch drums to take the line to.
If i had, I would not be looking to put an electric hoist on the system. (Look at my avatar pic and you will see the davits.)
I am considering the rope clutch for the possibility of launching the tender if a power failure occured, Like a fire in the generator or such. I would not be concerned with retrieving the tender very soon if that was the case.
I am aware of the slipperiness of Dyneema, but am curious as to how you cover the tails?
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Old 24-04-2018, 18:59   #4
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Re: Rope clutch and Dyneema line

the tricky way to get bare dyneema line to work in a clutch is to put an 'internal core' in . . . this is dead easy, just take a piece of any old quite small cord and pull it into/thru the hollow center of the dyneema (using a fid). This is very neat and clean and easy and gives the clutch something to crunch on. While the dyneema is still slippery, and the clutch will probably not hold its full rated load it will still hold quite a bit - we did this on quite highly loaded reef lines. it is the pro racer technique (volvo/vendee).

Thin's suggestion of putting a cover on the dyneema also works, is a bit more work and I think a bit less clean, if well done will hold higher load in the clutch, but the cover can slip - so is also a fine technique if you prefer it.
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Old 24-04-2018, 19:42   #5
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Re: Rope clutch and Dyneema line

I think a snubber drum would work for what you're trying to do.
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Old 18-11-2020, 14:06   #6
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Re: Rope clutch and Dyneema line

[QUOTE=estarzinger;2621333]the tricky way to get bare dyneema line to work in a clutch is to put an 'internal core' in . . . this is dead easy, just take a piece of any old quite small cord and pull it into/thru the hollow center of the dyneema (using a fid). This is very neat and clean and easy and gives the clutch something to crunch on.


Question: does the buried line be stitched to the dyneema line, so it stays in place? and if so on both sides or just front?
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Old 18-11-2020, 15:15   #7
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Re: Rope clutch and Dyneema line

[QUOTE=Kleim;3277254]
Quote:
Originally Posted by estarzinger View Post
the tricky way to get bare dyneema line to work in a clutch is to put an 'internal core' in . . . this is dead easy, just take a piece of any old quite small cord and pull it into/thru the hollow center of the dyneema (using a fid). This is very neat and clean and easy and gives the clutch something to crunch on.





Question: does the buried line be stitched to the dyneema line, so it stays in place? and if so on both sides or just front?

Yes, stitch along the full length of the buried core or an external cover. In both cases, straight stitches all the way through, then a second set of straight stitches at 90*. Can be done quite easily by hand, but a machine is easier if you have long lengths.

You can see the stitching on these chafe covers for our reefing lines, made from 8mm Acera Amundsen dyneema lines.

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Here are the covers on the reefing lines at the gooseneck end of the boom. The jammers are cams and really chew up the lines, so this has to be considered sacrificial and a regular wear item (a decent clutch like the Antal V-grip would be much easier on the line). Next time I will add a core as well as the cover. The red whippings are at the far ends of each cover and weíre done as burying the ends doesnít seem to work very well on the reefing lines.

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The only time you can avoid stitching an external cover is if you the original line was covered and you have removed the cover from one end. In that case the loading through the clutch will be to the covered end. The line will perform just as if you hadnít removed the cover.

This is our running backstay purchase line. It started out as a 12mm dyneema-core with dyneema-cover line. We stripped the cover for the section that goes through the LFR purchase. Note that we had to shop around for a dyneema-core line where the core has its own UV protection - many donít as thatís the coverís job.

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