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Dyneema splice strength again


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Long story short, what is strength decrease to dyneema if I don‘t bury the tail as usual, tapered and all, but have it exit as done with adjustable eyes?

Tried to find an answer but it was all about bend radius and splice length which I mostly already knew. Though still not sure if 24diameter bury is applicable anywhere anymore...

Asking since I want to carry some easy to store and reasonably light weight emergency shrouds made from 5mm dyneema in case the 4mm 1x19 wire gets damaged and I notice before the mast comes down. Something to keep sailing with no rigger at hand but not having to worry. 

Since I still want to carry as little as possible, And thought to simply use an adjustable eye so that main shrouds and forestay can be covered by the same prepared dyneema. Plus less worry to get the length/lashing right if I can just adjust the eye length and use a rigging screw.

 

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The forestay and shroud are a very different length. Your prepared loop will be completely wrong for one.

Do they have the same top fittings? How long will it take the spreader to destroy a bit of D12? Interesting idea but work to do I'd say.

It's say regular inspection and appropriate replacement is probably more practical.

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Could just carry a length of 4mm wire for the longest shroud/stay. If all the top fittings are the same have that swaged on and have a mechanical stud fitting and your all set. Yea you would wire cutters on board. 

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12 hours ago, Max Rockatansky said:

Rather than possibly compromising strength, just use a lashing to terminate, which is then adjustable. No?

I'd need to pay attention to equalizing the lashing correctly and have the right dead eyes, but an entirely viable option yes. About compromising strength otherwise, if it is within acceptable margin(5mm dyneema being significantly stronger than 4mm wire), I could easily live with that, hence the question.

Personally I'd prefer not having to splice anything at all.(easy method would be to simply taper the very long bury and simply pull out to the right length as needed before stitching. But then I'd also have to get it right which would require more prep than I want to sink into a measure unlikely to see use)

6 hours ago, European Bloke said:

The forestay and shroud are a very different length.

Actually not that much, I'd have to put them side by side when the opportunity arises, but from the top of my head its less than a meter for my boat.

6 hours ago, European Bloke said:

Do they have the same top fittings? How long will it take the spreader to destroy a bit of D12?

Yep, all use the same t-terminals(eye t-terminals available, but super expensive if original Selden. Cheaper not "perfect" fit on the market), so that is not an issue.
About the spreaders, I missed the opportunity to smoothly clean up the tips, but checked that I can fit pet or heatshrink tubing for chafe protection. Not ideal, but long lasting enough to finish vacation with some checks to control for potential chafe.

2 hours ago, mgs said:

Could just carry a length of 4mm wire for the longest shroud/stay.

Not an option. While I do already carry a wire cutter in order to be able cut the shrouds in case the mast ever comes down, stowing the extra wire is way too cumbersome and heavier than dyneema for my tastes. Plus I already carry the fittings, at that point I can go back to finding a local company that can make me some temporary wire but the idea was to not have to bother with any of that.

Dropping the mast and switching is a 20min affair once a little practiced and with two people. Dyneema would give me the opportunity to do so wherever with little weight penalty...

But I suppose I'll just keep carrying the t-terminal with an eye and a roll of dyneema to splice to length as usual instead of premaking them.

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Also, I need to bitch for a moment. How come virtually all suppliers make all but impossible to find info about their stuff online?!

https://support.seldenmast.com/en/products/rigging_hardware/toggles/t-eye_toggles.html?id=4571&item=174-137

This is the t-eye that should be the right one for my application. I even found someone that sells it, but hell if I can read anywhere if it actually has the load ratings it should. Why do I end up mailing everyone...

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12 minutes ago, allweather said:

Also, I need to bitch for a moment. How come virtually all suppliers make all but impossible to find info about their stuff online?!

https://support.seldenmast.com/en/products/rigging_hardware/toggles/t-eye_toggles.html?id=4571&item=174-137

This is the t-eye that should be the right one for my application. I even found someone that sells it, but hell if I can read anywhere if it actually has the load ratings it should. Why do I end up mailing everyone...

You’re grousing about the wrong stuff. 
 

https://bluewave.dk/products/small-t-rope-eye/

Whatta know, information.

 

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I would agree... but the last rigger pointed out that Bluewave‘s toggles aren‘t quite compatible with my Selden backing plates and I should not use them to avoid potential issues. Not likely to fail as such, but quicker wear or the like. 

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Well yes, doesn't mean I want to spend money on the wrong part intentionally. I would buy them if I hadn't found another supplier, but now I have to make said chandelier phone the company for data and it is just so unnecessary.

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Fair enough on the first part. But having someone make a phone call in name of customer service doesn’t seem like a hardship. 
 

but look at this: http://support.seldenmast.com/en/products/rigging_hardware/terminals/t-terminals.html?id=4502&item=308-322

the swage fitting doesn’t have load data associated with it because it matches the wire strength. 
 

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You read that this way as well? That is reassuring. Still annoys me since I always look for data sheets, but reassuring.

About the phone call? You're right, yet my practical experience is that dealer/local shop/etc can be an absolute pain this way and I subsequently prefer doing everything online with data seconds away instead. (there is also my... somewhat unusual mindset that I don't want to pay for the man's time when it comes to basic information, not even indirectly) Only go to shops for bigger projects and more individual solutions that I know are not available off the shelve.

Basically just a pet peeve of mine when there is gate keeping involved. Like when I wanted to buy some fittings and the distributor directs you at local sellers who all don't have online shops and are a pain to mail order through.

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allweather,

you've probably taken this into account already but AIUI when replacing wire with dyneema you need to size for stretch not strength. in my case for a headstay that meant going from 8mm wire to 12mm dyneema. is your 4mm wire and 5mm dyneema in the same realm stretch-wise?

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12 hours ago, ryley said:

when replacing wire with dyneema you need to size for stretch not strength.

Had to double check myself here since I do not know stretch/load characteristics off the top of my head.

I knew to to size so that creep is within an acceptable range(6mm would be ideal, 5mm somewhat lower bound but since its not a long term solution...). I was not aware that stretch characteristics differ significantly when using same diameter.

Going by the one table(rigging company this or that), for replacing 4mm wire 5-6mm dyneema is recommended which fits.
Do you happen to have better tables at hand?

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@allweather you probably saw the same table at Colligo, but here it is anyway:

https://static1.squarespace.com/static/556621c8e4b02628a8d3bde8/t/562688a5e4b08b7d50464bfa/1445365925954/Stretch+Equavalents.pdf

It only goes as low as 5mm wire but I *think* you would be right to go with 5-6mm for 4mm wire. However, I am not a rigger and it might be worth the call.

All in all, though, I think your idea is a good one. you could practically make up complete replacements and they'd take up less space than your dock lines.

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Yes, that is the chart I had seen as well.

And that is exactly the intent as you put it, six dock lines take up far more space(and weight) than some dyneema that also can be used for all kinds of things in a pinch.

Personally I have no issue carrying a spool and splice as needed, but the boat is also used by other family members on occasion who do not have the skills/confidence for that. Hence the idea to have some premade and labeled ones around.

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9 hours ago, estarzinger said:

I have pull tested it.

Thank you for that! SK99 in 5mm still leaves me above the break load of the rigging screws if done like that. 6mm would be severe overkill but maybe going for that with SK78 instead. We'll see, with which I mean I need to check how big the holes in the spreader tips are.

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  • 3 weeks later...

My issue is that lashing can be fucked up. For myself that may not be as much of an issue, but family sails the boat on occasion too and I am not going to diagnose a lashing over the phone, unlikely as it may be.

On the other hand it may be an option to do one/a strop as you mentioned to account for the differing length which would take out most of the guesswork I don't trust others with.(specifically equalizing strands)

On that note I actually measured everything to take away the guess work.
forestay: 8350
Main shrouds: 7960
lower shrouds: 4465

Too bad that the lowers aren't exactly half the main ones, that would be convenient. But as is I checked the numbers and prices for 5mm SK99. An entire shroud costs 25euro and is lightweight. Going to make at least separate main and lowers, though I may go for an extra strop with the forestay...

Or you know, keep it super simple as a proper emergency measure. Just a spool long enough for any one stay, thimbles for a lashing to get everything stretched and in the worst case redo the splice once to adjust length. It isn't that difficult or black magic.

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