Tether lines from Dyneema/other such fibres - DIY

antaris

antaris

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Would it be reasonable to deploy dyneema Tether lines (I have some lying around and thought to put it to good use)?

The only obvious disadvantage is low-stretch - albeit at the usual length of 1.5 metre no rope is that stretchy.

Also, difficulty to cut may be another issue - so why not use spinnaker-type shackles of that sort on harness end?
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Any real disadvantages? Other thoughts? Many thanks
 
I woulsn't use those snap shackles for the same reason I won't go up the mast on one.... all something has to do is catch that ring and you are toast.

What about carabiners instead?
 
Sure G12 - what you're saying does make sense. My idea was to utilise these snap shackles only because dyneema is quite hard to cut (compared to ordinary webbing) and the idea of being dragged on the side of your boat is pretty horrifying...
 
antaris said:
Sure G12 - what you're saying does make sense. My idea was to utilise these snap shackles only because dyneema is quite hard to cut (compared to ordinary webbing) and the idea of being dragged on the side of your boat is pretty horrifying...
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Have a look on the DMM Climbing Equipment website and see their demonstration of 2 ton Spectra webbing slings (same as dyneema) snapping when a human size weight drops a few feet onto it.

The warning is there for primarily climbers and those working at height. But essentially there can't be a less suitable material for lifeline 'cows tails' than dyneema.
 
TimBennet said:
Have a look on the DMM Climbing Equipment website and see their demonstration of 2 ton Spectra webbing slings (same as dyneema) snapping when a human size weight drops a few feet onto it.

The warning is there for primarily climbers and those working at height. But essentially there can't be a less suitable material for lifeline 'cows tails' than dyneema.
Click to expand...

Most interesting watch - many thanks.
 
I wouldn't use Dyneema for a tether for the same reason that I wouldn't use it for mooring. It's low stretch makes it unsuitable for absorbing shock loads... which is what a tether is meant to do before it stops you going overboard.
 
Here is a link to a tether designed for the job. To my dismay I see it has one of those snap shackles on the harness end. It has 2 tethers of different lengths and to permit one to move from one jack stay or attachment point to another. (100 squid is not cheap but supposedly approved) What is really vital is to ensure that your tether is long enough to do the job but short enough that you can not go over the side. You are likely to be dead meat if you go over the side spectra or webbing elastic or not. Simply because of the difficulty of getting back on board. good luck olewill
http://binksmarine.com.au/store/sai...rness-lines/wichard-osr-elastic-3-hook-tether
 
GHA said:
There's loads of stretch in a jack stay already, whatever your lanyard is made of will have little difference on the loads.
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Not necessarily, although I see what you mean. I have seen jack stays made out of 1/19 stainless wire or Dyneema/Spectra; they certainly have little or no stretch. Personally I do not like them because of rolling underfoot and I therefore prefer webbing that lies flat on the deck. Perhaps it is down to personal preference but I am not aware of any manufacturer who offers tethers made out of 'non-stretchy' material, not even at the higher end of the market.
 
William_H said:
Here is a link to a tether designed for the job. To my dismay I see it has one of those snap shackles on the harness end. It has 2 tethers of different lengths and to permit one to move from one jack stay or attachment point to another. (100 squid is not cheap but supposedly approved) What is really vital is to ensure that your tether is long enough to do the job but short enough that you can not go over the side. You are likely to be dead meat if you go over the side spectra or webbing elastic or not. Simply because of the difficulty of getting back on board. good luck olewill
http://binksmarine.com.au/store/sai...rness-lines/wichard-osr-elastic-3-hook-tether
Click to expand...

Yeap, saw this and that is what gave me the idea. Also, I thought that a snap-shackle is easier to release under tension...

Still, I see the points raised in this thread... webbing it is, then!
 
PuffTheMagicDragon said:
Not necessarily, although I see what you mean. I have seen jack stays made out of 1/19 stainless wire or Dyneema/Spectra; they certainly have little or no stretch. Personally I do not like them because of rolling underfoot and I therefore prefer webbing that lies flat on the deck. Perhaps it is down to personal preference but I am not aware of any manufacturer who offers tethers made out of 'non-stretchy' material, not even at the higher end of the market.
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Firstly, I don't think anyone could recommend dyneema as a restraint lanyard material. Though I have no problems using it, I made one up recently from some 8mm tech 12 with bungie inserted into the sore which works well. And single handed use a grigri with abseil dyneema which works a treat. Jackstays will provide loads more stretch than a short lanyard. But if I didn't get dyneema offcuts for free i'd stay with shop bought lanyards. Makes sense. :)
 
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