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Dockhead 02-01-2014 03:26

Quote:

Originally Posted by JonJo
Correct me if I'm wrong, again.

But a 10hp engine with a 'sized' prop is said to produce about 100kg of thrust, 20hp 200kg etc. 2 x 20hp 400kg.

We put our load cell on our chain once and measured the thrust, in reverse, 2 x 3 bladed Volvo props (sized for 20hp Volvos). It was very crude and we simply tried it and did not get very sophisticated (we did not not put on a snubber).

Loads at about 2,800 revs 350kg - but the load oscillated. So some of our 350kg might have been momentum. The yacht would move back, to 350kg and then moved forward, then back, then forward - we did not have a sustained 350kg (and 350kg is about the load on a anchor chain at 30/35knots at 7:1 scope for a 38'cat or 45' mono). I would have thought this oscillation greater with a full snubber attached and much of the reverse load 'stored' in the snubber and thus not transferred to the anchor (which is the other reason for not setting with the snubber on).

If you back up with snubber attached the snubber stretches, stores energy, some of the energy is also stored in the catenary - some of this is transferred to the anchor (but not much as its pretty transitory and an anchor takes 'time' to set (see Mantus' videos - its a slow process) but the yacht is not fixed and much will be transferred to the yacht, moving it forward. Consequently the power set with snubber - I have doubts as to effectiveness cf without snubber.

If our anchor does not set at 3:1 (which would be very unusual) we know its a difficult bottom. We might then move, easier if you have no snubber attached and only 25m deployed than 50m deployed. We would rather move, maybe not far, in the hope of finding something better. I'd rather know its difficult, on the 3:1 scope, than assume its a good hold having set at 7:1. One reason a full 50m deployment is not popular, for us, - if we need to move is that with a shallow chain locker we can only retrieve about 30m at a time, then need knock the tower over. I'd rather spend 30 minutes on the bow and get it right.

I have heard of people who set their anchor, put the engine(s) into reverse and drive hard back using a 'power' stop to set the anchor. We have never done this - we set and slowly increase the revs. As mentioned we can tell if the anchor is set from feel of the chain (and looking at transits and later GPS). But if the chain 'rattles' - we have an issue (maybe 5/16th inch chain is more sensitive to feel than 1/2 inch?)

Attaching a bridle on many cats is not difficult - its just a bit fiddly. The main issue is that the hook needs to be applied under the trampoline which usually means one handed (because there is only room to get one hand through whatever small aperture there is (the hook needs to be also released one handed). Consequently the Witchard hook or any hook with a gate is very difficult. But I see many monos with fold over bow rollers (common on Hanses) and chain hook attachment is well forward when the bow roller is folded out and would be best (easiest) done one handed - so any gated chain hook would need 2 hands on some monos.

But with a common 1m draft, with mini keels, having a fathom (2m) of chain between bow roller and hook is easy. In fact for us 2m would not be enough in a decent blow as the snubbers will stretch more than that.

I do not see that our practice is peculiar to a cat, except we have a bridle not a single line. Many bow arrangements with furlers, bow rollers on almost a sprit etc mean attaching a hook is a bit of a balancing act (or in our case lying on the tramp with one hand through a small hole). Hooks with gates seem overly fiddly (and unnecessary) if you have that fathom, or more, of chain providing the attachment. But havng the snubber so long that it touches the seabed seems, also, unnecessary if you have 10m of deck along which you could run the snubber.

Proof tested standard steel chain hooks are cheap and for us work (though we have used identical design AISI 316L stainless and much more expensive hooks).

But here - Snubbers, long, are like hens teeth. So for most it is simply not an issue:(.

Jonathan

I do it like JonJo. No snubber, and 3:1 scope while setting. Snubber, more scope make it much harder to feel what the anchor is doing in the bottom because of more elasticity/catenary. Gradually increasing revs to work the anchor into the seabed, culminating with a couple of minutes at redline (also blows carbon out of the engine after futzing around at low revs). If the anchor does not set at 3:1, then I move. Maybe there are some situations where it would hold at 5:1 where it wouldn't hold at 3:1, but seems to me that would be rare and marginal, so I prefer to just try a different spot.

Like Erstarzinger, I find transits to be as important as what you feel. Besides transits, I look at the plotter on max zoom. SOG suddenly going to 0.0 is a good sign of anchor setting. Then you can see the hard defined arc of a boat swinging around a well set anchor. The total of all these clues, and also including the feel of the taught chain with no rattling, will give a very clear picture of whether the anchor is solidly set or not. Only after all that, I let out final scope, attach snubber, and make cocktails.

Sid at SailAway 02-01-2014 09:13

Re: Mantus Chain Hook
 
Wow! All these numbers are making my head spin..Maybe I should have spent more time in math class!! :)

Cotemar 02-01-2014 10:20

Re: Mantus chain hook
 
1 Attachment(s)
Quote:

Originally Posted by Delfin (Post 1429097)
Starting to understand why you post what you post.

I am listening to the Baylor game so don't take the time to draw a picture, but.....

In a right triangle, if a = .5, b = .372, than c must necessarily = .62. So, a soft shackle made of line that is 50% of .62 inches, a.k.a. 5/16", will fit just fine between the links of 5/16" chain, and have a breaking strength greater than the chain.

A 5/16 Soft Shackle at a .550 finish diameter, may be a bit much to stuff through the 5/16 G4 chain link opening.

Delfin 02-01-2014 10:59

Re: Mantus chain hook
 
Quote:

Originally Posted by Cotemar (Post 1429462)
A 5/16 Soft Shackle at a .550 finish diameter, may be a bit much to stuff through the 5/16 G4 chain link opening.

Were a soft shackle not soft as your drawing suggests, quite true. It's not, so it feeds through. Give it a try if reality is your thing. 1/4", better and at 8,000# minimal tensile strength likely plenty strong enough.

thinwater 02-01-2014 11:24

Re: Mantus chain hook
 
Quote:

Originally Posted by Delfin (Post 1429488)
Were a soft shackle not soft as your drawing suggests, quite true. It's not, so it feeds through. Give it a try if reality is your thing. 1/4", better and at 8,000# minimal tensile strength likely plenty strong enough.

I do know that a 3/16" soft shackle doesn't fit 1/4" G4 chain; I have to go to 1/8", which is cutting it a little thin. As Cotemar explained, G4 chain is tight between the links.

Cotemar 02-01-2014 11:47

Re: Mantus chain hook
 
Quote:

Originally Posted by Delfin (Post 1429488)
Were a soft shackle not soft as your drawing suggests, quite true. It's not, so it feeds through. Give it a try if reality is your thing. 1/4", better and at 8,000# minimal tensile strength likely plenty strong enough.

I had tried putting a 1/4 Soft Shackle and a 5/16 Soft Shackle through a 5/16 G4 chain this summer with no luck, But if you say it works I will dig up my piece of 5/16 G4 chain tonight and see if I can give it another go on the 1/4 and 5/16 Soft Shackles.

Cotemar 02-01-2014 12:10

Re: Mantus chain hook
 
1 Attachment(s)
Quote:

Originally Posted by thinwater (Post 1429499)
I do know that a 3/16" soft shackle doesn't fit 1/4" G4 chain; I have to go to 1/8", which is cutting it a little thin. As Cotemar explained, G4 chain is tight between the links.

You can jump up one size on your Soft Shackle from 1/8 to a
5/32" Amsteel line diameter, (.156) which has a 4,000 lbs tensile strength and a .300 finish dia.

Delfin 02-01-2014 13:28

Re: Mantus chain hook
 
Quote:

Originally Posted by thinwater (Post 1429499)
I do know that a 3/16" soft shackle doesn't fit 1/4" G4 chain; I have to go to 1/8", which is cutting it a little thin. As Cotemar explained, G4 chain is tight between the links.

Yes, I think the limitation is that the soft shackle shouldn't exceed the diameter of the links, which would still give it greater strength than the chain. The shackle's profile is nominally that of a rectangle - 1 x in one dimension and 2 x in the other. So the fact that you can't shove the darn thing through the link opening on the x axis doesn't prevent you from rotating it and inserting it on the y access or even diagonally, which is wider. Further, they're soft, so they mush down. I'm holding in my hot little hand a 3/8" Plasma shackle that at the loop, smushes down pretty well so it should fit through a 3/8" chain. Not saying it isn't tight, but if one were concerned that the soft shackle would be a weak link, it needn't be.

thinwater 02-01-2014 15:02

Re: Mantus Chain Hook
 
My thought is that while I probably can stuff a soft shackle in the G4 space, at that point there are easier ways. No big deal. Looks slick for other chain.

I do love my soft shackles on my genoa clew, though.

Delfin 02-01-2014 16:01

Re: Mantus Chain Hook
 
Quote:

Originally Posted by thinwater (Post 1429682)
My thought is that while I probably can stuff a soft shackle in the G4 space, at that point there are easier ways. No big deal. Looks slick for other chain.

I do love my soft shackles on my genoa clew, though.

Sensible. I'm trying to go for the strongest attachment point to the chain I can get, because I wonder about chafe of the shackle. Other than that, the stretchy part of my snubber is light enough to stretch around 4', at which point I want either the chain to take over, or if I am expecting a serious blow, another larger diameter snub line that will absorb energy before the chain is engaged.

NorthPacific 02-01-2014 19:39

Re: Mantus Chain Hook
 
So with soft shackles, how much does the knot (the weak link) effect the working load?

estarzinger 02-01-2014 20:14

Re: Mantus Chain Hook
 
Quote:

Originally Posted by NorthPacific (Post 1429927)
So with soft shackles, how much does the knot (the weak link) effect the working load?

It is hard to know exactly . . . But the theoretical strength is 400% of the cord strength and the best anyone seems to have measured in a finished shackle is 200%, and it always breaks at the knot, so probably the knot weakens it by about half. . . . And that is consistent with the testing showing the "good" knots in general cut dyneema line strength about in half .

Panope 02-01-2014 22:43

Re: Mantus Chain Hook
 
I asked this question over on the "soft shackle thread" but got no response.

Can a extra long soft shackle be "doubled up" by looping through two (or more) chain links?

Steve

NorthPacific 03-01-2014 00:57

Re: Mantus Chain Hook
 
estarzinger that is what always was the rule when I climbed. Ropes kind of important once in a while. Guess no method is fail safe. How about a prussic knot? I dock friend swears by them? Anyone used those?

estarzinger 03-01-2014 05:51

Re: Mantus Chain Hook
 
Quote:

Originally Posted by Panope (Post 1430060)
I asked this question over on the "soft shackle thread" but got no response.

Can a extra long soft shackle be "doubled up" by looping through two (or more) chain links?

Steve

You don't gain any strength by just running the soft shackle up or down thru multiple chain links. But if you mean to loop it multiple times back and forth between the snubber and chain links (like a lashing) you do gain strength (actually quite a bit, more than linear, because the diamond knot is the weak point and it is only on one loop)

thinwater 03-01-2014 07:47

Re: Mantus Chain Hook
 
Quote:

Originally Posted by estarzinger (Post 1430180)
You don't gain any strength by just running the soft shackle up or down thru multiple chain links. But if you mean to loop it multiple times back and forth between the snubber and chain links (like a lashing) you do gain strength (actually quite a bit, more than linear, because the diamond knot is the weak point and it is only on one loop)

In my testing--and I have not tested this many times--a knot has the effect of weakening every loop in the lashing; they all carry the same load and the weakest one breaks. In testing of climbing sling we see the same thing; the knot breaks at it's rated strength, even if the loop is doubled several times.

This explains why it is best practice to use either a spliced eye or a high-strength knot to start the lashing, and finish with a long chain of half hitches; the half hitches cinch down on the bundle but do not weaken the line. Mostly we just add a a few more turns to allow for this weakening and UV.

Or at least that is how I understand it. Something to test! Parrachute cord lashings with several different knots (a spectra lashing might break the rig!).

jcapo 03-01-2014 09:09

Re: Mantus Chain Hook
 
Quote:

Originally Posted by NorthPacific (Post 1430088)
How about a prussic knot? I dock friend swears by them? Anyone used those?

I use long shackles and prusik knots. Works great no chafe.

estarzinger 03-01-2014 10:45

Re: Mantus Chain Hook
 
Quote:

Originally Posted by thinwater (Post 1430232)
In testing of climbing sling we see the same thing; the knot breaks at it's rated strength, even if the loop is doubled several times.

That is completely counter intuitive to me . . . (if I understand you)

Don't we know this just from a simple sling - the sling breaks (at the knot) at twice the load which will break that same knot and line in a single rope/straight line pull?

I would have thought that the load on a knot on one strand of say a doubled sling (which then has 4 legs between the load points) would only be (about) 1/4 the entire load.

estarzinger 03-01-2014 11:54

Re: Mantus Chain Hook
 
2 Attachment(s)
OK,

single loop: breaking 1020lbs
Attachment 73211


double loop breaking 2240lbs
Attachment 73212

Same line and same double sheet bend on both.

It seems clear to me that using a soft shackle as a double loop will cut the loads on the diamond in half and double the system strength.

Ignore the extra safety line I have on the double loop picture to catch the shackle during post break recoil.

Panope 03-01-2014 12:29

Re: Mantus Chain Hook
 
Quote:

Originally Posted by estarzinger (Post 1430450)

It seems clear to me that using a soft shackle as a double loop will cut the loads on the diamond in half and double the system strength.

Ignore the extra safety line I have on the double loop picture to catch the shackle during post break recoil.

This is what I was thinking as well.

My concern with doubling up on chain, is the possibility of pinching or squeezing the loop that passes through the chain link that is closest to the anchor.

I hate to ask you to ruin more of your stuff but I would love to see a test of this concept on chain.

Steve

thinwater 03-01-2014 12:49

Re: Mantus Chain Hook
 
Quote:

Originally Posted by estarzinger (Post 1430373)
That is completely counter intuitive to me . . . (if I understand you)

Don't we know this just from a simple sling - the sling breaks (at the knot) at twice the load which will break that same knot and line in a single rope/straight line pull?

I would have thought the load on a knot on one strand of say a doubled sling (which then has 4 legs between the load points) would only be (about) 1/4 the entire load.

I'm sure I did not explain well. Just as likely, I didn't understand you.

Certainly, more passes = less load per pass. Simple proportion.

However, if there are 4 passes (doubled sling), the materials tests 2500#, but the stitching weakens one leg to 2000 pounds, the double sling should fail at 4x2000=8000#. Weakest link.

I tried making a very long soft shackle and luggage-tagging it around the chain; this way I could get the strength. It was stiff and awkward, to me. Instead, I often use a standard 60cm climbing sling (5000 pounds--enough for my 34' catamaran) girth hitched around the chain (takes about 1 second), connected to the apex of a nylon bride with a 3/16" soft shackle or big SS biner. I like the biner because it only takes 1 hand on or off. If I was forced to cut away the sling to move, who cares. They seem to last through ~ 100 days of anchoring before they look poor. If I wanted to cut costs, the nylon ones are $5, though I just use something retired from climbing. Dyneema is available for $9. Bigger boats would need to splice something; 5' of 1/4" Amsteel would make a nice rabbit runner.

estarzinger 03-01-2014 13:35

Re: Mantus Chain Hook
 
Quote:

Originally Posted by thinwater (Post 1430498)
However, if there are 4 passes (doubled sling), the materials tests 2500#, but the stitching weakens one leg to 2000 pounds, the double sling should fail at 4x2000=8000#. Weakest link.
.

agreed . . . "number of passes x the weakest link".

and not "(n-1) x full strength + 1 weakest"

estarzinger 03-01-2014 13:41

Re: Mantus Chain Hook
 
I just did three quick nylon 3 strand pulls, of the three most common rope to chain splices, and they were all "full strength".

The three methods were (a) the conventional 3 strand loop splice thru the last link, ( b ) the 2 strands one way thru the last link and the 3rd strand the other way loop splice", and ( c ) the "up the chain weave'.

All tested to full rope strength, but not so surprising, because while the bend radius inside the first link is less than 1:1 when the rope is fully round with all three strands, it is more than 1:1 to each of the separate 3 strands, and they do separate and mash out when in all these splices (least perhaps in (a) )

But the answer here seems to be "it does not matter so long as you do any of teh splices well".

thinwater 03-01-2014 17:10

Re: Mantus Chain Hook
 
Quote:

Originally Posted by estarzinger (Post 1430536)
I just did three quick nylon 3 strand pulls, of the three most common rope to chain splices, and they were all "full strength".

The three methods were (a) the conventional 3 strand loop splice thru the last link, ( b ) the 2 strands one way thru the last link and the 3rd strand the other way loop splice", and ( c ) the "up the chain weave'.

All tested to full rope strength, but not so surprising, because while the bend radius inside the first link is less than 1:1 when the rope is fully round with all three strands, it is more than 1:1 to each of the separate 3 strands, and they do separate and mash out when in all these splices (least perhaps in (a) )

But the answer here seems to be "it does not matter so long as you do any of teh splices well".

I have read of a 2-strand link splice that is said to pass a windlass more easily and is still 100% strength. It was like a long splice, but I forget the details. It sounds good, so long as redone a bit more often.

Auspicious 04-01-2014 05:55

Re: Mantus Chain Hook
 
Quote:

Originally Posted by Cotemar (Post 1428802)
Auspicious,

Unfortunately, Life testing a new Bridle Snubber design takes years and I am past year one right now.

<snip>

If you want to do the proper analysis of this Bridle Snubber, you will need a 3D CAD model of the rubber snubber and 3 strand 5/8” dia. nylon line. When you’re done with the 3D CAD model, then you can export out a .stp file and bring it over to your Ansys software for doing your simulation and analysis.

I will be out sailing when you’re doing simulation and analysis.

Certainly don't need a 3D CAD model. The math is simple to model a system like a rode and snubber.

You say the snubber doubles shock absorption. I'm just asking for substantiation.

Quote:

Originally Posted by Cotemar (Post 1428877)
Rubber Snubbers in the Bridle Snubber just remove the shock load.
The snubber elements themselves possess a nonlinear stress-strain curve.
The Snubber reduces the expected peak shock load loads 50%

The rubber snubbers you have cited are linear (F = kx) except as loads approach yield. Yield means you are working in a failure regime. That just doesn't make sense to me. You'll have to explain and justify your statement for me to understand.

Quote:

Originally Posted by Dockhead (Post 1429175)
This has been discussed before. You need more than just the snubber to take load off the gypsy! The snubber is designed for shock absorption, not UTS! The chain should be belayed in some manner (chain lock, belaying strop) first, then back down. Only then, attach the snubber for shock absorption.

Why? Ultimate strength of the structural member (in this case rode and snubber, with or without rubber snubber) has nothing to do with the loads backing down. You just won't be putting enough power into the water to come anywhere close to ultimate tensile strength while backing down unless your ground tackle is grossly undersized.

My anchoring protocol is to get the anchor down, let the anchor settle, rig the snubber, and run a bunch of chain out to unload the gypsy. There is zero load (aside from the weight of the chain itself hanging in a loop between the anchor roller and the chain hook) when I back down at cruising rpm.

I simply don't understand your point. UTS is not relevant in this scenario.

Delfin 04-01-2014 10:08

Re: Mantus Chain Hook
 
1 Attachment(s)
Quote:

Originally Posted by Auspicious (Post 1431030)
Certainly don't need a 3D CAD model. The math is simple to model a system like a rode and snubber.

You say the snubber doubles shock absorption. I'm just asking for substantiation.



The rubber snubbers you have cited are linear (F = kx) except as loads approach yield. Yield means you are working in a failure regime. That just doesn't make sense to me. You'll have to explain and justify your statement for me to understand.

I presume the charts published by the line or rubber snubber manufacturers showing stretch as a function of load are accurate so I figure I can leave my Cray 1000 turned off to design a snub line. As you say, elongation is quite linear relative to load and not hard to calculate.

I'm experimenting with an Ultra rubber snubber that allegedly won't fall apart under load. I'm open to such snubbers being pointless, but I added one for a couple of reasons, none of which has to do with "reducing peak shock loads by 50%", which doesn't make sense to me either. My reasons were that, at least for my vessel, to anchor in 60 knots winds would require the stretchy bit to be 3/4" if I wanted to stay within a safe working load on the line. However that is too robust for other conditions, so my thought was to provide energy absorption in 3 stages. First, the rubber snubber stretches along with a 5/8" plait line 30' long. Once the rubber has reached its maximum energy absorption the plait bears the load. This will work fine up to around 35 knots. If conditions are expected to be windier, then I overlay a 3/4" 3 strand line that would begin to take the load after 5 feet of stretch had been induced. The bight of chain would then take the load when the 3/4" line had stretched another 6'. Since all chain hooks I have looked at are no stronger than a Dux soft shackle, I prefer to use those to attach the snubs lines to the chain.

The other reason for using the rubber snubber is to give me a visual indication of load values. I can rig the snubber inboard so it is easy to see from the pilot house and get an idea of what shock loads are actually being absorbed.

Beats me if this is a good approach or not, but time will tell.

Auspicious 04-01-2014 10:13

Re: Mantus Chain Hook
 
Quote:

Originally Posted by Delfin (Post 1431252)
I presume the charts published by the line or rubber snubber manufacturers showing stretch as a function of load are accurate so I figure I can leave my Cray 1000 turned off to design a snub line. As you say, elongation is quite linear relative to load and not hard to calculate.

Exactly. It's all about F=kx - all linear.

Your other bits make sense also, although I do much the same with just line.

Cotemar 04-01-2014 10:30

Re: Mantus Chain Hook
 
2 Attachment(s)
Quote:

Originally Posted by Delfin (Post 1431252)
The other reason for using the rubber snubber is to give me a visual indication of load values. I can rig the snubber inboard so it is easy to see from the pilot house and get an idea of what shock loads are actually being absorbed.

Beats me if this is a good approach or not, but time will tell.

The Ultra Snubber Bridle looks like a very nice piece of kit. A bit pricy though as one for my cat would cost $307 usd.

My Bridle Snubber cost $120 usd

Purchase ULTRA Snubbers | Quickline USA

Delfin 04-01-2014 10:47

Re: Mantus Chain Hook
 
Quote:

Originally Posted by Cotemar (Post 1431270)
The Ultra Snubber Bridle looks like a very nice piece of kit. A bit pricy though as one for my cat would cost $307 usd.

My Bridle Snubber cost $120 usd

Purchase ULTRA Snubbers | Quickline USA

Agreed. I also don't see the point of the chain hook, and prefer to have a bit of Dyneema leading from the cleat to the stretchy line. I put the rubber on the Dyneema, and I think I paid $50 or something for that component. Still pricey, but it does seem very robust.

estarzinger 04-01-2014 12:11

Re: Mantus Chain Hook
 
1 Attachment(s)
Crossing posting with my load testing thread . . . a test of load vs stretch in three nylon constructions:

As expected, nylon double braid is the least stretchy.* But the difference between good old 3 strand and Brait was not as big as expected, and at least with these particular lines (Yale 1/2" brait and Samson pro-set 1/2") and loads the 3 strand was marginally stretchier.

Attachment 73287

colemj 04-01-2014 12:20

Re: Mantus Chain Hook
 
Those are interesting numbers. We switched our bridles from 3-strand to 8-strand and noticed a significant difference in stretch and "smoothness". The 8-strand was Buccaneer Rope brand and we have had 2 of these over the years. Recently, I just made up a bridle using Yale Brait, and the difference in "hand" and splicing qualities was very different than the Buccaneer. The Brait was much more "hard" and "tight" than the Buccaneer - which may explain the linearity with double braid and deviation from 3-strand for lower loads.

This wasn't from memory - due to circumstances, I had a length of Brait and a length of Buccaneer and each now form a leg of our new bridle. We haven't had a chance to use this frankenbridle yet, but I wonder if we will notice differences in stretchiness between the legs?

If you get ahold of some Buccaneer plait, I would be interested in its stretch compared to Brait and 3-strand.

Mark

estarzinger 04-01-2014 12:31

Re: Mantus Chain Hook
 
I agree with you that there are probably significant difference between the various different braits. And they may well 'age' differently, and differently than 3 strand.

I had planned to test the nylon up to 2500lbs, but I ran out of hydraulic travel at 1000lbs. I am getting a longer ram in order to better test nylon but it has not come yet.

So, I will come back to this later.

JonJo 04-01-2014 14:45

Re: Mantus Chain Hook
 
Quote:

Originally Posted by estarzinger (Post 1431366)
I agree with you that there are probably significant difference between the various different braits. And they may well 'age' differently, and differently than 3 strand.

I had planned to test the nylon up to 2500lbs, but I ran out of hydraulic travel at 1000lbs. I am getting a longer ram in order to better test nylon but it has not come yet.

So, I will come back to this later.

I have seen the same results from another cordage maker, which thus shows some consistency. 3 strand has more elasticity initially but anchor plait has a higher ultimate elasticity. But the differences are marginal, or not something that I think anyone would really notice. Beyond about 50% of total elasticity (approx 50% of UTS) any results are a bit academic as we should not be loading that high anyway - which means 3 ply is better. I use 3 strand in a mixed rode, because I have it, if I was buying from new I'd buy anchor plait simply because its easier to handle (and the elasticity differences not great).

Elasticity vs diam is a function of weight, rather than diameter - again I have not checked but is 3 strand heavier (or lighter) than the same nominal diameter anchor plait.

It would be interesting to look at different plaits, braids or 3 strand as manufacturers seem to show different elasticities to each other - but I do wonder if they have smoothed the curves - which means looking at manufacturers data is flawed - someone would need to actually do it (and you would need an awful lot of different cordage - not something I can easily acquire as Americans think exporting is selling from NY to Cal:(

Jonathan

0urh 05-01-2014 23:33

Re: Mantus Chain Hook
 
What about using a 4WD snatch strap as a bridle/snubber?:flowers:

"The Mean Mother Snatch um Strap is made in Australia and rated at 8,000kgs giving you plenty of strength to get your 4WD out of a mess.
This strap is 9 metres long by 60mm wide and is made from High Tenacity nylon webbing with reinforced and protected eyes and has been Thermofixed and treated for long wear.
This snatch strap has a high elongation rate of 20% making it ideal for pulling your mate out of a bog."
https://dtfdl8d42g4o8.cloudfront.net/...b35ab6d43a29a9


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