What breaks when we test our Dyneema Chainplate Loops to 4000kg? Dyneema Standing Rigging Episode 3
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- Опубліковано 5 вер 2024
- What broke when we loaded our novel Dyneema Chainplates to 4,000kg? Something did, but what?
We want to be sure that the Dyneema loops we are building our chainplate system around will be strong enough to sail around the world on our 44 year old boat!
In Dyneema Episode 2 we test tensioned our chainplate loops (held in our FR4 backing plates) to 1,000kg. That started to remove the constructional stretch but it wasn't enough to be confident they were strong enough nor that we had removed all the stretch. However, with a 1,000kg scale and a 1,500kg pull-along we needed to change things to get enough tension. This shows how we got to test at more than 4,000kg.
We are changing all the standing rigging on our 1977 Rival 38 to Dyneema synthetic rigging. That includes all shrouds, stays and even the chainplates for both masts of our ketch rig.
To learn how to make these see • Make an EASY Amsteel s... ("Make an EASY Amsteel soft shackle with overhand knot - includes break tests!" from HowNOT2)
This is the third episode in our Dyneema series that will cover all the design choices, the practicalities of a completely DIY re-rig and then how it works out when we go sailing.
Our goal is a rig that is:
- stronger
- lighter
- cheaper
- allows us to sail faster
- lasts longer
- can be DIY maintained even replaced, anywhere in the world
We are refitting a 44 year old Rival 38 for a Sustainable Sailing retirement in a few years. Two years ago, when we bought Vida she was in a very tired and damp condition with all original equipment and fittings (much of it not working). We have removed all the gas, diesel and paraffin equipment, and are installing all electric (motor, cooking etc).
Our masts are both down and have been almost completely stripped, then painted with:
2 coats epoxy primer (with epoxy filler between coats)
1 coat of two part undercoat
2 coats of two part top coat
We have fitted new FR4 backing plates for the mizzen chainplates and are getting ready to do the backing plates for the main mast chainplates.
Our Chainplates are essentially an overhand knot soft shackle with the "eye" above deck (the shrouds get lashed to this). The knot is below the backing plate.
Not only are we fitting Dyneema chainplates we are also having a Dyneema forestay which means no roller reefing. So we are modifying our original sails to be hank on (with webbing hanks). We have upgraded our Bow Roller to support this.
Lots more detail on our blog at sustainablesai...
If you would like to encourage us then you can support us on Ko-Fi!
ko-fi.com/sust...
Or visit our shop at sustainablesai...
#DyneemaRigging
#DyneemaStandingRigging
#BoatRefit
Greetings from Florida, US. Thanks for taking the time to record this awesome test! I have used 10mm dyneema with lashings for my lowers for the last 3 years- no issues. Can't wait to see those chain plates finished!
Thanks Ed. Hoping to be ready to get the mizzen up in the next few weeks.
What size dyneema do you use for the lashing and how many turns?
@@SustainableSailing the lashings are 3mm line. I believe 5 turns (I just went around until I ran out of line) I do find that spraying water on the lashings lubricates enough to help with tightening.
The water is a good tip. We want to save up for a bigger scale so we can measure input and output to compare different lashing options.
Then we can make a more educated guess about the shroud tension by measuring the pull on the lashing.
Hi. I´m emjoying watching your videos. I´m building a cat and putting dyneema stays on it. I see you are taking the dangers of loading up lines quite seriously. I work offshore, sometimes using hundreds of tons of force. This type of loading is where dyneema shines. Dyneema does not stretch much, so if it breaks, it falls dead down. Your come along with the steel wire is actually the dangerous bit, as the steel wire stretches, so that is where you need to pay attention. Seems you got it though. I have composite chainplates on my boat... What i would like to get rid of is the toggles. Looking at options. Thanks for the videos. / Axel.
If you want to have a look at stupid amounts of fairing, check out Building Wilda. We´ll get back to Wilda in a few months, now that Australia is open for visitors again.
Thanks. Good to hear from your knowledge and experience.
With a 1000kg scale and 1500kg come along we shouldn't get close to its limit.
Interesting test! Something to consider, a 5:1 purchase won't actually deliver 5 times the force in reality, not even with ball-bearing blocks. There is a lot of losses to friction, which seems to grow in an almost non-linear fashion as the purchase goes up.
There are a number of good videos here on UA-cam showing tests of this :)
This setup probably gave you atleast 3-4 times the input force though, so pretty valid test still :)
We definitely want to put together a rig that will measure both the input into tensioning the lashing and the output in terms of shroud tension. Then we can directly compare different numbers of turns, different line thickness, low friction rings vs metal thimbles etc.
We haven't seen much that closely relates to tensioning a shroud where the pull is consistent and slow so that there is more opportunity for the tension to equalise around the lashing.
So hoping to get a clear test rig sorted when we can afford the extra scale etc.
@@SustainableSailing sounds like a great plan!
I'd assume that a design line your chainplates should be possible to calculate from the strength of the line, as you say, dyneema padeyes are not that uncommon these days:) but an actual test is of course always preferred!
It's also probably a good idea to pre stretch your loops before installing them in the deck, just to get the constructional stretch out and get the splice and knots to really settle in before you start tensioning the rig.
Are you going full dyneema rigging? I don't think I've seen all your videos on the subject yet, so it may be a redundant question :)
We figure that in all the soft shackle tests (when properly tapered) the break is where the loop is pulled into the knot. We don't have that. Therefore, our untested assumption is that with a chainplate loop made from the same dyneema as the shroud our weakest dyneema point is going to be the shroud locking brummel splices (we haven't been able to load up to breaking point yet, but we are already massively stronger than the original stainless steel).
We are going to pre-stretch everything but with a long slow pull so the knots and splices bed gently. Much less likely to slip or be uneven then.
Yup we are going fully dyneema for both masts and including the forestay. So no roller reefing instead short term we are converting our old headsails to be webbing soft hanks. Long term we want roller furling which will hoist aft of the forestay (so it will look a bit like solent setup but with a bare forestay forward of what will be a roller furling yankee - the forestay can be used for a hank on genoa for a twin headsails downwind setup). There is quite a lot on our blog from before we started doing UA-cam seriously about the rig plans.
I have wondered if a water based lube like KY would allow the knot to tighten down more consistently and would then wash away and dry up?
Worth a try. We want to get setup to test a whole range of ideas, like this, in a consistent way. First, we needed to make more refit progress while the weather is better.
I would want to repeat the failure to test if the same failure happens an how to stop it ( lubricant maybe like water?)
What I’d you plan to stop the chainplates leaking?
( or should I say rigging terminations?)
Cheers Warren
Hi Warren,
Lubricant would be one possibility. Or just upgrade from 4mm to 5mm with larger low friction rings. Or possibly a cascading low friction ring purchase to replace the 4th turn around the low friction ring.
But I don't think we are very eager to go for more tension at the moment - too scary.
As for leaks we are implementing a deck mushroom to stop water flowing into the hole in the deck. Plus a fabric sleeve for the lashing to protect from chafe and UV while also reducing the amount of water running down into the chainplate loop. Finally a simple water collection around the knot under the deck.
@@SustainableSailing
Hi, thanks for making this series of videos about dyneema rigging.
I'd really like to see how you solved the problem of stopping leaks around the chainplate loops.
You mention a 'deck mushroom'. I'm not exactly sure how that would work. Can you show this in detail, please?
Many thanks,
Daniel
@@dansidi1 we haven't got to implementation fully. Our idea is to have 4 parts.
a) The "mushroom" stops water flowing along the deck going into the hole for the chainplate loop
b) the top flange of the mushroom allows a fabric tube around the lashing and upper part of the chainplate loop to be cinched into place. So water on the outside of this tube (that protects against chafe and UV) doesn't go into the chainplate loop hole.
c) we will seal around the chainplate loop (probably with butyl), this won't stop water running inside the weave but will stop most.
d) the chainplate loop knot under the deck will be covered by a watertight "box" to catch any drips.
As soon as we get to this we will put videos up.
@@SustainableSailing
Thanks for your reply. I look forward to seeing how this looks.
I expect you might need a drain of some kind in the knot box under the deck, or perhaps there wouldn't be too much liquid in there and it may just evaporate or wick away?
@@dansidi1 agreed. Time will tell.
what varient of Dyneema was it? SK75, SK78, Dux?
The lashing is 4mm - LIROS D Pro "100% dyneema SK78 with a special polyurethane coating"
The mizzen chainplate loops (and mizzen shrouds) are 9mm DynIce Dux SK75 "DynIce Dux is a heat-set, pre-conditioned 12 strand synthetic fibre Dyneema® line which, according to Hampidjan, outperforms other Dyneema® SK75, SK78 and SK99 versions.
The Hampidjan special engineering process removes all the constructional elongation during manufacture, making it much stronger while delivering less stretch and creep."
Both from Jimmy Green Marine.
The DynIce is definitely not flexible enough to be used for a lashing.