Dyneema D12 and spinlock clutches

[Ian_Edwards]

Hi All,
I've just replace a 12mm d2 main halyard with a12mm d12, a SK90 without a cover.
I also uprated the main halyard clutch to a new spinlock xx0812.
The new halyard has got rid of the halyard stretch, and using 6 turns on a Lewmar 46 electric halyard winch I can get the tension required without the dyneema slipping.
But the spinlock clutch won't hold the load, if I release the halyard from the winch the halyard slips for about 300mm before holding.
The mainsail is about 60 sq m and the airdraft of the boat is 22.5m.
In practice, this isn't too much of a problem, the halyard winch is only used for the main and 1st and 3rd reefing penants, I obviously have to release the main halyard to put the reef in.
I've been thinking about adding a cover to the d12 in the area where the clutch has to grip, I have some cover stripped of a 12mm rope, but I'm not sure how to go about fixing the cover to the d12.
How much cover do I need to put ahead of the clutch to ensure a good grip?
and
How do I tuck the strands of the cover into the d12 to ensure that I don't get a snag?
Can anyone point me to an oneline source which show me how to do it?

 

[DHV90]

two options really

you could try a traditional method of attaching an extra cover:
https://www.youtube.com/watch?v=thyLfoOHe-4

But what I'd probably do is use a taper splice on both ends of the extra cover like this:

https://www.youtube.com/watch?v=0aol6bSQLo4

And make sure you use a long cover. Youll need halyard grip all the way from the part that is in the clutch for whatever your deepest reef is up to fully hoisted.

Dyneema halyards really really need a cover, you might be better off with getting a length of double braid dyneema and then tapering the working end for the last couple of meters. Theres not a lot to be gained on having bare dyneema the rest of the length, but a lot to be lost! Slipping clutches and then worrying about slipping stitched on covers takes away all benefit of getting rid of halyard stretch.

 

[Ian_Edwards]

Thanks for the prompt reply.
I've looked at the videos on youtube and there seem to be two different ways of adding a cover, one is to bury the cover in the core, in the same way you'd do a splice in hollow 12 strand. The second is to unravel the cover and stitch 4 threads at a time into the core. The second option is much more time consuming, probably less bulky, but I don't think it would be as strong.
I was thinking more about putting 3 seperate covers on the halyard at the points where the halyard will be for the 3 reefs. Making each cover at least 1m long, to allow for the slight difference each time the sail is reefed.
Is ther anything wrong with that approch?
It's Selden single line reefing on the first two reefs, seperate pennants on the 3rd reef, all led back to the cockpit.
Having just shelled out for a new 50m length of 12mm d12, I don't want to buy and tapper another new halyard.
I was also disapointed that the new spinlock xx0182 didn't hold th eload

 

[Javelin]

I use this technique with my halyards.
Biggest issue is I downsized from 12mm braid on braid to 8mm dyneema so had to build up the dia for the clutches.
It doesn't actually take that long to do.

 

[Ian_Edwards]

I use this technique with my halyards.
Biggest issue is I downsized from 12mm braid on braid to 8mm dyneema so had to build up the dia for the clutches.
It doesn't actually take that long to do.

Did you do that for just the areas where the clutches need to grip the rope, or for the full length from full hoist to 3rd reef?

 

[Javelin]

All the non handling parts of the dyneema is just plain core but the areas that either go round winches or through clutches are double or in the case of no3 reef treble layered.
I have a small half a meter section on the main halyard at the top where it goes over the sheave but its probably me being a bit anal.
My no3 reef is 4mm dyneema so needed to bump it up a lot for the last few feet for the selftailer winch.
Yes could have used thicker rope but my racing habits are still in evidence, don't like additional windage/weight where I can avoid it, plus thinner rope has less friction.

 

[Ian_Edwards]

Thanks for the clarification, I'll give a go as soon as I have some down time to work on the halyard.

 

[DHV90]

I use this technique with my halyards.
Biggest issue is I downsized from 12mm braid on braid to 8mm dyneema so had to build up the dia for the clutches.
It doesn't actually take that long to do.

Out of curiosity, does this method work for bare hollow core 12 strand dyneema? I would gave assumed that this would be less effective on single braid than on double braid, but it would be very handy to know it works on single braid dyneema!

 

[Ian_Edwards]

For what it's worth I think it probably would work on bare 12 strand hollow core dyneema, which is what my main halyard is.

However, I'm going to try using this method:

https://www.youtube.com/watch?v=hnIp-Uzlpqs

I don't see why it won't work on bare 12 strand hollow core dyneema, it's very similar to the way you'd do a Brummel splice, and looks much faster than stitching 4 threads at a time. It also looks like it would be fairly easy to remove without damaging the main rope.

 

[DHV90]

That method is the same splice as the second link I posted, which shows how it works on single braid for clarity:

https://www.youtube.com/watch?v=0aol6bSQLo4

and definitely works extremely well on hollow braid, Ive used it a lot. Dead quick and with a long tapered tuck it looks really clean and tidy, with a nice gradual blend in diameter from the single to doubled braids.

 

[Ingwe]

Out of curiosity, does this method work for bare hollow core 12 strand dyneema? I would gave assumed that this would be less effective on single braid than on double braid, but it would be very handy to know it works on single braid dyneema!

Yes it does still work, but you can't make it look anything like as neat because the sewn threads of the new cover have nothing to be buried under in the way that they do when you are putting an additional cover over the top of an existing cover.

Also just a small point for the OP but you are intending to put a 2mm cover over a 12mm rope and then put it through a 12mm clutch .... so I would do a small test section first to make sure that you aren't going to end up with lots of friction.