new generation rope

[pdenton]

What are possible applications of HMDPE eg Dyneemo. 10 mm breaking strength 11,000 # could be used as part of an anchor rode?

[salticrak]

I would not use it due to it's low stretch qualities.

[tkeithlu]

Agreed. Hell of a halyard or main sheet, but without the shock absorbing qualities of nylon or even chain.

[Snowpetrel]

A lot of fishing boat used to anchor in deep water with wire rope. Id be happy enough with spectra, as long as I had a stretchy snubber of some sort.

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[UNCIVILIZED]

Originally Posted by Snowpetrel

A lot of fishing boat used to anchor in deep water with wire rope. Id be happy enough with spectra, as long as I had a stretchy snubber of some sort.

Sent from my SM-G930F using Cruisers Sailing Forum mobile app

How would you attach a snubber to it? As it's so slippery that even the rope's own jacket slides around on it a good bit.

Also, I'm thinking that the only practical way to attach a snubber to it's core/bare Dyneema, would be to splice another short section of line into the rode, which would have an eye & thimble on the end of said short line.
So then, how do you decide where to install such pendants, & why in those locations? Plus, if said pendants ever happen to lay on the bed of the sea floor, I'd think that they'd present a big snagging risk.

Plus which, it's cost is on par with chain, if not higher. But without the advantages of chain. Including lifespan, ease of cleaning, & abrasion resistance. And a few more.
Also, given it's specific gravity, it's far more likely to fouls a prop, or wrap your keel, than all but a handfull of other line types (that are purpose designed to float.

[Delancey]

Prolly could attach a snubber using one of these.

[Delancey]

Inspired by a knotless connector intended for spectra fishing shown below. Works as advertised. No slip. Stupid simple.

http://www.cruisersforum.com/forums/...nk-138917.html

[estarzinger]

Originally Posted by pdenton

What are possible applications of HMDPE eg Dyneemo. 10 mm breaking strength 11,000 # could be used as part of an anchor rode?

French cruisers used a technique with polypropylene anchor line (which floats and is relatively low stretch like dyneema) in Polynesia - developed/designed to avoid snagging coral heads.

To add shock absorption what they did is tie one or several big fenders (usually big orange balls but it does not make any difference) to about the middle of the rode. This acts sort of like chain catenary but in reverse. The balls would be pulled down in gusts absorbing shock loading. It seemed to work but I never personally tried or tested it.

As to tying onto dyneema - I tested 4 different gripper hitches and the icicle was the best and will hold to a pretty high load - the hitch actually broke rather than slipping (12mm dyneema and 3/16 icicle). For a snubber you would need to play around with this - would need a stronger line for the icicle but larger diameter I believe holds less well - but that is a path I would pursue. I guess I would start by trying the same small diameter but in a multiple loop to get extra strength while still having the small diameter gripping.

[Snowpetrel]

All valid points uncivilised, but there are also some big plusses to dyneema, its low stretch and abrasion resistance make it very chafe resistant. Its low weight can be a big advantage in some situations, such as rowing out a kedge.

The problems you mention can all be overcome with a bit of lateral thinking. The biggest issues are really cost, and it floating.

Its interesting that the dashews have gone to dyneema mooring lines, as have most ships and deepwater mooring systems.

Id like to have 100 meters of the stuff for my kedge anchor, where its lightweight and low stretch would be a big advantage. The floating would also help when rowing it out.

Id also use the length for shore lines, a drogue line, a very deep water extension for my normal chain, and a tow line. To give it some stretch Id copy the big shios and use a nylon tail at one end, eg for anchoring id go chain, then 10m of nylon, then the dyneema.

I would stow it on a reel to reduce the chance of tangles and splice big loops in either end. Maybe it would be worth splitting it into 2x50 meter lengths?

[pdenton]

I'm new to the forum and very impressed with the number of responses and all the different suggestions. MY feeling is that it is clearly a technological advance and I would like to integrate it. Chain is inelastic but has many advantages, but under high loads can snap i.e. fail suddenly. An all-chain rode is a consequence of the problem of winching a rope and chain. The most important reason for chain is to load the anchor horizontally with the line providing elasticity.
I'm out-fitting a boat I just bought, a Pearson 35, which has a small anchor locker. I have bought two shots 5/16 G4, 90' each. I have a Rocna 35 and supermax 35 mounted. A 45# Mantus in reserve. To match the chain i have 150' of double braid. So in such a small boat if I could somehow integrate a reel of spectra it would save weight and volume. A wet rope can weigh more than chain.
The catenary effect only counts at low loads, but is a plus. the idea of a float as a reverse catenary is interesting. Maybe a kellet could help.
Indeed the worst problem is fouling the prop.
PHD, PhD

[thinwater]

Originally Posted by pdenton

I'm new to the forum and very impressed with the number of responses and all the different suggestions. MY feeling is that it is clearly a technological advance and I would like to integrate it. Chain is inelastic but has many advantages, but under high loads can snap i.e. fail suddenly. An all-chain rode is a consequence of the problem of winching a rope and chain. The most important reason for chain is to load the anchor horizontally with the line providing elasticity.
I'm out-fitting a boat I just bought, a Pearson 35, which has a small anchor locker. I have bought two shots 5/16 G4, 90' each. I have a Rocna 35 and supermax 35 mounted. A 45# Mantus in reserve. To match the chain i have 150' of double braid. So in such a small boat if I could somehow integrate a reel of spectra it would save weight and volume. A wet rope can weigh more than chain.
The catenary effect only counts at low loads, but is a plus. the idea of a float as a reverse catenary is interesting. Maybe a kellet could help.
Indeed the worst problem is fouling the prop.
PHD, PhD

Personally, it would be simpler to go with 1/4" G70 and use a nice long nylon snubber (>30'). Much simpler. Truthfully, 1/4" G43 would be enough with a good snubber. That is the rig I use on a 34' cat. With a long snubber, the loads just are not that high.

Funny thing, in Sail this month they had a story where the wise sailor blames his snubber failure on age, when the real problem was that it was simply too short to absorb the energy--it takes length. He was in shallow water, so the chain catenary went bye-bye. Not going to learn much from that article.

[UNCIVILIZED]

Wow, these are some great ideas & insigthts on this topic. And it'll be interesting to find out how well some of them work. As it surely would be nice to replace a spool of high volume rope, like 3-strand nylon, with a svelte spool of Dyneema. Especially from a space onboard perspective, ditto on line weight.

I've always been curious about the use of Polypro rope for mooring & anchor lines, from the perspective of it's low UV resistance. Because aside from that, it would seem to have several plusses to it. Particularly in terms of when one needs to row out a shore line, or spare anchor.

[Snowpetrel]

I agree that its hard to beat all chain for a primary anchor system. I see future applications where dyneema rode might be preferable to a nylon rode for a secondary system, or exceptionally deep water anchoring. Especially given the potential issues with nylon chafing and heating up at high loads. Cost is the biggest real issue, and given the amount you can downsize due to the extra strength the real extra cost may not be that much more than nylon brait rope of equivalent strength.

Looks like there are plenty of options to add a nylon snubber and that float/drag trick really does work exceptionally well to damp peak loads and yawing, without the bounce associated with a long nylon snubber, kind of like a cars shock absorber.

[RaymondR]

Originally Posted by thinwater

Personally, it would be simpler to go with 1/4" G70 and use a nice long nylon snubber (>30'). Much simpler. Truthfully, 1/4" G43 would be enough with a good snubber. That is the rig I use on a 34' cat. With a long snubber, the loads just are not that high.

Funny thing, in Sail this month they had a story where the wise sailor blames his snubber failure on age, when the real problem was that it was simply too short to absorb the energy--it takes length. He was in shallow water, so the chain catenary went bye-bye. Not going to learn much from that article.

A trick I have used with a nylon snubber on a chain mooring system in shallow water was to run it over the bow chain roller back along the deck and cleated it off on an aft cleat.

I think that because it is stretchier nylon has the highest energy absorption capacity when used as a snubber but poly tends to float and not snag on things by dragging about on the bottom when used for anchoring.

[Dockhead]

Originally Posted by Snowpetrel

I agree that its hard to beat all chain for a primary anchor system. I see future applications where dyneema rode might be preferable to a nylon rode for a secondary system, or exceptionally deep water anchoring. Especially given the potential issues with nylon chafing and heating up at high loads. Cost is the biggest real issue, and given the amount you can downsize due to the extra strength the real extra cost may not be that much more than nylon brait rope of equivalent strength.

Looks like there are plenty of options to add a nylon snubber and that float/drag trick really does work exceptionally well to damp peak loads and yawing, without the bounce associated with a long nylon snubber, kind of like a cars shock absorber.

I think single braid dyneema could be quite all right as the secondary part of a mixed rode, after a goodly length of chain. Compared strength to strength, it is not actually more expensive than other materials, or not much more. It has far superior chafe resistance. Being slippery and hard, it will be far easier to chafe-proof, and it won't suffer from internal heating or the other problems of normal rope. I don't think you care so much about shock absorption if you have 100 meters or 60 meters or whatever of heavy chain ahead of it, especially if you have a decent way to attach a snubber.

I think it's a promising idea.